William H Seiple, Ph.D.

Clinical value, normative retinal sensitivity values, and intrasession repeatability using a combined spectral domain optical coherence tomography/scanning laser ophthalmoscope microperimeter
Anastasakis, A; McAnany, J J; Fishman, G A; Seiple, W H
2011 Feb;25(2):245-251, Eye
PURPOSE: To establish normative values for macular light sensitivity and to determine the intrasession fluctuation of perimetric responses using the OPKO/OTI microperimeter. METHODS: A total of 32 visually normal subjects participated in the study. A standardized grid pattern was used for testing, which consisted of 28 points arranged concentrically in three circles that occupied an area of 11 degrees (in diameter) within the central macula. Each subject participated in at least two tests. Parameters evaluated included: overall mean macular sensitivity for test 1 and 2, overall difference in mean macular sensitivity between tests, and the mean sensitivity for each circle. The relationship between sensitivity and age was also examined. RESULTS: The overall median sensitivity for test 1 was 16.8 decibels (dB) and for test 2 was 16.9 dB. The median sensitivities for test 1 and test 2 were not significantly different (P = 0.72). The mean intrasession sensitivity difference was 0.13 dB. The variability of the sensitivity difference between tests decreased as mean sensitivity increased. The sensitivity values averaged across the two tests for inner, middle, and outer circles ranged from 14.3 to 18.8 dB (median value of 16.9 dB), 13.8-18.3 dB (median value of 17.2 dB), and 11.3-18.3 dB (median value of 16.6 dB), respectively. Linear regression analysis showed a 0.5 dB sensitivity loss for each decade of life. CONCLUSION: We documented a narrow range of intrasession fluctuation using the OPKO/OTI microperimeter. The establishment of normative sensitivity values will facilitate monitoring the loss of macular visual function in patients with retinal disease
— id: 138302, year: 2011, vol: 25, page: 245, stat: Journal Article,

Effect of depression on actual and perceived effects of reading rehabilitation for people with central vision loss
Grant P.; Seiple W.; Szlyk J.P.
2011 ;48(9):1101-1108, Journal of rehabilitation research & development
To investigate the relationship between depression and quantitative measures of visual function, we recruited 18 subjects with central scotomas from macular degeneration who were enrolled in a reading rehabilitation program. Psychological batteries and reading assessments were administered prior to rehabilitation; reading assessments and a measure of adaptation to vision loss were administered following rehabilitation. We investigated relationships between reported levels of depressive symptoms and reading and adaptation outcome measures by using Pearson product moment correlation analysis.Results revealed a significant relationship between depression levels and reading acuity difference scores (r(16) = 0.54, p = 0.02) and changes in adaptation to vision loss levels (r(16) = 0.62, p = 0.01), suggesting that those who reported greater depressive symptoms did not respond as well functionally to reading rehabilitation but reported greater improvement in levels of adaptation to vision loss following rehabilitation. Future research should focus on defining standard methods to assess and remediate depression as part of the rehabilitation process
— id: 147737, year: 2011, vol: 48, page: 1101, stat: Journal Article,

INNER SEGMENT-OUTER SEGMENT JUNCTIONAL LAYER INTEGRITY AND CORRESPONDING RETINAL SENSITIVITY IN DRY AND WET FORMS OF AGE-RELATED MACULAR DEGENERATION
Landa G; Su E; Garcia PM; Seiple WH; Rosen RB
2011 Feb;31(2):364-370, Retina
PURPOSE:: To investigate a relationship between the inner segment-outer segment (IS-OS) junctional layer integrity and the overlying retinal sensitivity assessed by Spectral OCT/SLO (spectral-domain optical coherence tomography) and microperimetry testing in patients with dry and wet forms of age-related macular degeneration (AMD). METHODS:: Spectral-domain optical coherence tomography examination and microperimetry testing were performed in 55 eyes of 43 consecutive patients with AMD. Microperimetry maps were registered onto three-dimensional retinal topography maps, and point-to-point analysis of correlation between microperimetric retinal sensitivities and corresponding status of the underlying IS-OS junctional layer was performed. In addition, the analysis of correlation between the best-corrected visual acuity and the integrity of IS-OS layer in the center of fovea was also performed. RESULTS:: Retinal sensitivity was inversely and strongly correlated with the integrity of IS-OS layer in both dry and wet forms of AMD (correlation coefficient [r] = -0.75 [95% confidence interval, 0.49-0.88], P < 0.001, and -0.79 [95% confidence interval, 0.61-0.89], P < 0.001, respectively). The correlation between the best-corrected visual acuity and the integrity of IS-OS layer in the center of fovea was less significant (r = -0.58 [95% confidence interval, 0.19-0.79], P = 0.02, for dry AMD, and r = -0.6 [95% confidence interval, 0.32-0.78], P = 0.015, for wet AMD). CONCLUSION:: Retinal sensitivity consistently correlated with the status of underlying IS-OS junctional layer in both dry and wet forms of AMD. Loss of IS-OS layer is significantly associated with poor retinal sensitivity, assessed by microperimetry. Compared with visual acuity, functional testing with microperimetry appears to more consistently correlate with changes in the outer retina, such as IS-OS junctional integrity, especially, in patients with wet AMD
— id: 120542, year: 2011, vol: 31, page: 364, stat: Journal Article,

Reading rehabilitation of individuals with AMD: relative effectiveness of training approaches
Seiple, William; Grant, Patricia; Szlyk, Janet P
2011 ;52(6):2938-2944, Investigative ophthalmology & visual science. IOVS
PURPOSE: To quantify the effects of three vision rehabilitation training approaches on improvements in reading performance. METHODS: Thirty subjects with AMD participated in the training portion of the study. The median age of the subjects was 79 years (range, 54-89 years). The three training modules were: Visual Awareness and Eccentric Viewing (module 1), Control of Reading Eye Movements (module 2), and Reading Practice with Sequential Presentation of Lexical Information (module 3). Subjects were trained for 6 weekly sessions on each module, and the order of training was counterbalanced. All subjects underwent four assessments: at baseline and at three 6-week intervals. Reading performance was measured before and after each training module. A separate group of 6 subjects was randomly assigned to a control condition in which there was no training. These subjects underwent repeated assessments separated by 6 weeks. RESULTS: Reading speeds decreased by an average of 8.4 words per minute (wpm) after training on module 1, increased by 27.3 wpm after module 2, and decreased by 9.8 wpm after module 3. Only the increase in reading speed after module 2 was significantly different from zero. Sentence reading speeds for the control group, who had no reading rehabilitation intervention, was essentially unchanged over the 18 weeks (0.96 +/- 1.3 wpm). CONCLUSIONS: A training curriculum that concentrates on eye movement control increased reading speed in subjects with AMD. This finding does not suggest that the other rehabilitation modules have no value; it suggests that they are simply not the most effective for reading rehabilitation
— id: 136462, year: 2011, vol: 52, page: 2938, stat: Journal Article,

Combined three-dimensional spectral OCT/SLO topography and Microperimetry: steps toward achieving functional spectral OCT/SLO
Landa, Gennady; Rosen, Richard B; Garcia, Patricia M T; Seiple, William H
2010 ;43(2):92-98, Ophthalmic research
AIMS: To investigate the combination of 3D optical coherence tomography (OCT) retinal thickness measurements and superimposed scanning laser ophthalmoscopy (SLO) microperimetry obtained using a Spectral OCT/SLO and to test the correlation between retinal thickness and retinal sensitivity in retinal diseases grouped according to anatomic locations. METHODS: Patients with various retinal diseases and subjects with normal fundi underwent microperimetry testing and imaging with the Spectral OCT/SLO. Based on the Spectral OCT/SLO findings, the participants were divided into 4 groups: patients with retinal thickening due to the outer retina pathology (group I); patients with retinal thickening due to the cystic changes observed in the inner retina (group II); patients with macular neurosensory retina thinning associated with geographic atrophy or underlying subretinal cicatricial changes (group III), and subjects with unremarkable fundus appearance and normal appearing retina on Spectral OCT/SLO (group IV). The primary outcome was the correlation coefficient (r) between Spectral OCT/SLO-measured macular thickness and microperimetry values. RESULTS: Correlations between retinal thickness and psychophysical thresholds were calculated for each patient, and these values were averaged within groups. The mean correlation values (Pearson product movement) were as follows: for group I (n = 21 eyes) r = 0.04; for group II (n = 24 eyes) r = -0.53; for group III (n = 16 eyes) r = 0.41, and for group IV (n = 15 eyes) r = 0.04. CONCLUSIONS: The combination of 3D OCT images and superimposed SLO microperimetry obtained by Spectral OCT/SLO demonstrated that thickening due to cystic changes of the inner retinal layers or thinning of the neurosensory retina on OCT correlated most significantly with decreases in psychophysical threshold sensitivities
— id: 120543, year: 2010, vol: 43, page: 92, stat: Journal Article,

A Comparison between Microperimetry and Standard Achromatic Perimetry of the Central Visual Field in Eyes with Glaucomatous Paracentral Visual Field Defects
Lima, V C; Prata, T S; De Moraes, C G V; Kim, J; Seiple, W; Rosen, R B; Liebmann, J M; Ritch, R
2010 Jan;94(1):64-67, British journal of ophthalmology
BACKGROUND AND AIMS: We correlated retinal sensitivity as determined by scanning laser ophthalmoscope microperimetry (SLO-MP) in glaucomatous eyes with paracentral visual field (VF) defects detected by standard automated perimetry (SAP). METHODS: Twenty eyes with glaucomatous optic neuropathy and a SAP VF defect involving the central 16 test points (at least one point with p<1% in the 24-2 VF) were enrolled. Eyes with diseases other than glaucoma were excluded. All patients underwent SLO-MP and SAP of the central 10 degrees. Results from each eye were divided into 4 quadrants for analysis. Normal and abnormal quadrants by SAP were compared to the corresponding normal and abnormal quadrants by SLO-MP. Regression analysis was used to correlate the mean threshold values (dB) of SLO-MP and SAP in each quadrant. Macular optical coherence tomography (OCT) was performed when there was a disagreement between functional tests. RESULTS: Mean age and VF mean deviation were 60.8+/-13.4 years and -7.3+/-6.1 dB, respectively. There was a significant correlation between SLO-MP and SAP results in all quadrants (r2>/=0.68, p<0.001). All abnormal SAP quadrants had a corresponding abnormal SLO-MP quadrant. However, 21% of the normal SAP quadrants had an abnormal corresponding microperimetry result; a corresponding significant reduction in total macular thickness measured by OCT was present in 75% of these quadrants. CONCLUSIONS: Macular sensitivity evaluated by SLO-MP correlates significantly with SAP paracentral VF defects. SLO-MP detected retinal sensitivity reduction in areas of OCT structural damage with normal SAP and suggests that subtle paracentral functional deficits may be present in many more eyes with established glaucoma than generally assumed
— id: 101613, year: 2010, vol: 94, page: 64, stat: Journal Article,

PREFERRED RETINAL LOCUS IN MACULAR DISEASE: Characteristics and Clinical Implications
Greenstein, Vivienne C; Santos, Rodrigo A V; Tsang, Stephen H; Smith, R Theodore; Barile, Gaetano R; Seiple, William
2008 Oct;28(9):1234-1240, Retina
PURPOSE:: To investigate the location and fixation stability of preferred retinal locations (PRLs) in patients with macular disease, and the relationship among areas of abnormal fundus autofluorescence, the PRL and visual sensitivity. METHODS:: Fifteen patients (15 eyes) were studied. Seven had Stargardt disease, 1 bull's eye maculopathy, 5 age-related macular degeneration, 1 Best disease, and 1 pattern dystrophy. All tested eyes had areas of abnormal fundus autofluorescence. The PRL was evaluated with fundus photography and the Nidek microperimeter. Visual field sensitivity was measured with the Nidek microperimeter. RESULTS:: Of the 15 eyes, 4 had foveal and 11 had eccentric fixation. Eccentric PRLs were above the atrophic lesion and their stability did not depend on the degree of eccentricity from the fovea. Visual sensitivity was markedly decreased in locations corresponding to hypofluorescent areas. Sensitivity was not decreased in hyperfluorescent areas corresponding to flecks but was decreased if hyperfluorescence was in the form of dense annuli. CONCLUSION:: Eccentric PRLs were in the superior retina in regions of normal fundus autofluorescence. Fixation stability was not correlated with the degree of eccentricity from the fovea. To assess the outcomes of treatment trials it is important to use methods that relate retinal morphology to visual function
— id: 94011, year: 2008, vol: 28, page: 1234, stat: Journal Article,

Macular structure and vision of patients with macular heterotopia secondary to retinopathy of prematurity
Soong G.P.; Shapiro M.; Seiple W.; Szlyk J.P.
2008 ;28(8):1111-1116, Retina
PURPOSE: To examine if vision in subjects with macular heterotopia (MH) secondary to retinopathy of prematurity (ROP) is related to anatomical macular structure. METHODS: Six subjects with MH who were between 18 years and 65 years of age and three age-matched subjects with normal vision were recruited for the study. Vision and macular structure of the better eye of the subjects with MH and the dominant eye of age-matched subjects with normal vision were assessed. High contrast visual acuity and contrast sensitivity were measured using Early Treatment of Diabetic Retinopathy Study and Pelli-Robson charts, respectively. The Micro Perimeter (Nidek Technologies MP-1) was used to assess macular sensitivity and fixation stability. Using optical coherence tomography, macular thickness and relative retinal thickness at fixation were measured. RESULTS: Subjects with MH had significantly reduced visual acuity and macular sensitivity compared with age-matched subjects with normal vision. In comparison with their age-matched counterparts, subjects with MH had significantly increased macular thickness and increased relative retinal thickness at fixation. A normal foveal architecture was absent in three subjects with MH (50%). CONCLUSION: Patients with MH secondary to ROP have increased macular thickness and reduced vision. Copyright copyright 2008 by the Ophthalmic Communication Society Inc
— id: 102150, year: 2008, vol: 28, page: 1111, stat: Journal Article,

Detection of mosaic retinal dysfunction in choroideremia carriers electroretinographic and psychophysical testing
Vajaranant, Thasarat S; Fishman, Gerald A; Szlyk, Janet P; Grant-Jordan, Patricia; Lindeman, Marty; Seiple, William
2008 Apr;115(4):723-729, Ophthalmology
PURPOSE: To test whether choroideremia carriers have a mosaic pattern of retinal dysfunction, as noted in carriers of X-linked recessive retinitis pigmentosa and X-linked retinoschisis. DESIGN: Prospective observational case series. PARTICIPANTS: Seven obligate choroideremia carriers (age range, 18-72) with visual acuity (VA) of 20/25 or better were recruited into the study. METHODS: The carriers underwent VA testing (Snellen chart), ophthalmic examination, Humphrey visual field (VF), and multifocal electroretinographic testing. The amplitude and implicit time scales were measured by the algorithm of Hood and Li. The amplitude measures (a scales) and implicit time measures (t scales) were reported abnormal when they were >2 standard deviations above the mean of age-similar normally sighted control subjects. MAIN OUTCOME MEASURES: Mapping of local 103 electroretinographic response amplitudes and implicit times. RESULTS: Only 1 of the 7 carriers showed abnormal Humphrey VF thresholds, whereas 6 of the 7 carriers showed a mosaic pattern of retinal dysfunction measured by multifocal electroretinographic testing. All 6 carriers showed statistically significant implicit time delays, whereas 4 carriers showed statistically significant amplitude reductions and implicit time delays (P<0.05 to P<0.0006). One carrier with a normal-appearing macula and normal Humphrey VF showed a cluster of statistically significant implicit time delays within the macula (P<0.05 to P<0.0006). The overall extent of local electroretinographic abnormalities corresponded to the severity of ophthalmoscopically apparent pigmentary changes. The one carrier with mild threshold elevation on Humphrey VF testing showed the most ophthalmoscopically apparent extensive fundus pigmentary changes. CONCLUSIONS: We demonstrated a mosaic pattern of retinal cone dysfunction in carriers of choroideremia. Our findings are consistent with the Lyon hypothesis of random X-chromosome inactivation. Multifocal electroretinographic testing is potentially sensitive to detect local retinal dysfunction in choroideremia carriers even in those with a normal-appearing macula and good VA
— id: 135340, year: 2008, vol: 115, page: 723, stat: Journal Article,

Scotopic sensitivity and color vision with a blue-light-absorbing intraocular lens
Greenstein, Vivienne C; Chiosi, Flavia; Baker, Paul; Seiple, William; Holopigian, Karen; Braunstein, Richard E; Sparrow, Janet R
2007 Apr;33(4):667-672, Journal of cateract & refractive surgery
PURPOSE: To investigate possible adverse effects of a yellow-tinted intraocular lens (IOL) on scotopic sensitivity and hue discrimination. SETTING: Departments of Ophthalmology, Columbia University and New York University School of Medicine, New York, New York, USA. METHODS: Nine patients with a yellow-tinted IOL in 1 eye and a colorless ultraviolet IOL in the fellow eye and 9 young phakic subjects with and without a yellow-tinted clip-on lens were tested. Hue discrimination was measured with the Farnsworth-Munsell (FM) 100-hue test. Dark-adapted thresholds to 440 nm, 500 nm, and 650 nm lights were measured at 23 locations using a modified Humphrey perimeter, and dark-adapted thresholds to white light were measured at 15 degrees temporal retina. RESULTS: In the 9 patients, there were no significant differences in dark-adapted sensitivities to 440, 500, 650 nm, or white-light stimuli and no differences in FM 100-hue error scores between eyes with yellow-tinted IOLs and those with colorless IOLs. Similarly, in young phakic subjects, there were no significant differences in FM 100-hue error scores or dark-adapted sensitivity to the white light with and without the yellow-tinted clip-on lens. However, with the clip-on lens, mean sensitivities to the 440 nm, 500 nm, and 650 nm stimuli were significantly decreased by 2.7 to 2.8 dB, 0.7 to 1.0 dB, and 0 to 1.2 dB, respectively. CONCLUSION: Results suggest that implantation of a yellow-tinted IOL has non-significant effect on scotopic sensitivity and hue discrimination
— id: 71300, year: 2007, vol: 33, page: 667, stat: Journal Article,

Eccentricity-dependent changes in local onset and offset responses in patients with progressive cone dystrophy
Holopigian, K; Wynn, P; Seiple, W; Carr, R E; Hood, D C
2007 Aug;47(17):2297-2304, Vision research
Shinoda and colleagues hypothesized that patients with cone dystrophy (CD) might suffer from a selective ON-system deficit, based on the local nature of the disease [Shinoda, K, Ohde, H, Inoue, R, Ishida, S, Mashima, Y, & Oguchi, Y (2002). ON-pathway disturbance in two siblings. Acta Ophthalmologica Scandinavica, 80, 219-223]. The purpose of the current study was to test this hypothesis by examining onset and offset responses as a function of eccentricity in a group of patients with CD using long-duration LED stimuli. Nine patients with CD participated in this study (mean age of 36.1 years and visual acuity 20/200). For this study, the following measures were obtained: Humphrey threshold visual fields, standard multifocal ERGs (mfERGs) as well as mfERGs to long duration stimuli recorded using the Retiscan stimulator (Roland Instruments). This display contained 61 scaled hexagons and the LEDs were on for 100ms (180cd/m(2)) and off for 100ms. In addition, standard full-field photopic and flicker ERGs using Ganzfeld stimulation were obtained. For the control subjects, the onset responses were larger than the offset responses at all eccentricities; whereas for the patients, there was overlap between the amplitudes of the onset and offset responses. For the patients, the amplitude ratios (relative to the control data) indicated that the difference between the onset and offset responses was greatest for the central-most ring and this difference decreased with increasing eccentricity. For the onset responses, Humphrey thresholds and mfERG amplitudes, performance was poorest for the center ring and best for the most peripheral ring; for the offset responses, the opposite pattern of results was obtained. The differences in the pattern of results in the long duration mfERG data are consistent with a selective loss of the onset responses in our patient population
— id: 73870, year: 2007, vol: 47, page: 2297, stat: Journal Article,

Retinal dysfunction in carriers of bardet-biedl syndrome
Kim, Linda S; Fishman, Gerald A; Seiple, William H; Szlyk, Janet P; Stone, Edwin M
2007 Sep;28(3):163-168, Ophthalmic Genetics
PURPOSE: To determine whether retinal dysfunction in obligate carriers of the Bardet-Biedl syndrome (BBS) could be observed in local electroretinographic responses obtained with the multifocal electroretinogram (mfERG). METHODS: Six obligate carriers of the BBS were examined for the study. Examination of each carrier included an ocular examination and mfERG testing of one eye. For the mfERG, we used a 103-scaled hexagonal stimulus array that subtended a retinal area of approximately 40 degrees in diameter. The amplitudes and implicit times in each location for the mfERG were compared with the corresponding values determined for a group of 34 normally sighted, age-similar control subjects. RESULTS: Mapping of 103 local electroretinographic response amplitudes within a central 40 degrees area with the mfERG showed regions of reduced mfERG amplitudes in three of six carriers. Implicit time measurements in the 6 carriers were all normal except for those locations associated with abnormal amplitude reductions in 3 of the carriers. When present, retinal dysfunction was evident in the presence of a normal-appearing fundus. CONCLUSIONS: Multifocal ERG testing can demonstrate areas of retinal dysfunction in carriers of the BBS. This test may therefore be useful for identifying some heterozygous carriers of this disease
— id: 94305, year: 2007, vol: 28, page: 163, stat: Journal Article,

Multifocal ERG findings in carriers of X-linked retinoschisis
Kim, LS; Seiple, W; Fishman, GA; Szlyk, JP
2007 JAN ;114(1):21-26, Documenta ophthalmologica
Purpose: To determine whether retinal dysfunction in obligate carriers of X-linked retinoschisis (XLRS) could be observed in local electroretinographic responses obtained with the multifocal electroretinogram (mfERG). Methods: Nine obligate carriers of XLRS (mean age, 46.2 years) were examined for the study. Examination of each carrier included an ocular examination and mfERG testing. For the mfERG, we used a 103-scaled hexagonal stimulus array that subtended a retinal area of approximately 40 degrees in diameter. The amplitudes and implicit times in each location for the mfERG were compared with the corresponding values determined for a group of 34 normally-sighted, age-similar control subjects. Results: Mapping of 103 local electroretinographic response amplitudes and implicit times within a central 40 degrees area with the mfERG showed regions of reduced mfERG amplitudes and delayed implicit times in two of nine carriers. Conclusions: The mfERG demonstrated areas of retinal dysfunction in two carriers of XLRS. When present, retinal dysfunction was evident in the presence of a normal-appearing fundus. Multifocal ERG testing can be useful for identifying some carriers of XLRS
— id: 70759, year: 2007, vol: 114, page: 21, stat: Journal Article,

Perifoveal function in patients with North Carolina macular dystrophy: the importance of accounting for fixation locus
Seiple, William; Szlyk, Janet P; Paliga, Jennifer; Rabb, Maurice F
2006 Apr;47(4):1703-1709, Investigative ophthalmology & visual science. IOVS
PURPOSE: To quantify the extent of visual function losses in patients with North Carolina Macular Dystrophy (NCMD) and to demonstrate the importance of accounting for eccentric fixation when making comparisons with normal data. METHODS: Five patients with NCMD who were from a single family were examined. Multifocal electroretinograms (mfERGs) and psychophysical assessments of acuity and luminance visual field sensitivities were measured throughout the central retina. Comparisons of responses from equivalent retinal areas were accomplished by shifting normal templates to be centered at the locus of fixation for each patient. RESULTS: Losses of psychophysically measured visual function in patients with NCMD extend to areas adjacent to the locations of visible lesions. The multifocal ERG amplitude was reduced only within the area of visible lesion. Multifocal ERG implicit times were delayed throughout the entire central retinal area assessed. CONCLUSIONS: ERG timing is a sensitive assay of retinal function, and our results indicate that NCMD has a widespread effect at the level of the mid and outer retina. The findings also demonstrated that it is necessary to account for fixation locus and to ensure that equivalent retinal areas are compared when testing patients with macular disease who have eccentric fixation
— id: 63839, year: 2006, vol: 47, page: 1703, stat: Journal Article,

Contrast response properties of magnocellular and parvocellular pathways in retinitis pigmentosa assessed by the visual evoked potential
Alexander, KR; Rajagopalan, AS; Seiple, W; Zemon, VM; Fishman, GA
2005 AUG ;46(8):2967-2973, Investigative ophthalmology & visual science. IOVS
PURPOSE. To evaluate the contrast response of the visual system in retinitis pigmentosa ( RP) under conditions designed to emphasize the parvocellular (PC) and magnocellular (MC) pathways. METHOD. Visual evoked potentials (VEPs) were measured in 10 patients with RP and in 10 age-equivalent control subjects with normal visual acuity and color vision, by using an array of isolated checks that were presented against a steady yellow background. The checks were modulated sinusoidally, either in isoluminant chromatic contrast (5.6 Hz), to favor the chromatic PC pathway, or in luminance contrast ( 5.6 and 11.2 Hz), to favor the MC pathway. Response amplitude and phase at the stimulus ( fundamental) frequency were derived from Fourier analysis, and contrast response functions were fit with a Michaelis-Menten equation to derive R-max, the maximum response amplitude, and sigma, the contrast necessary to produce R-max/2. RESULTS. In the control subjects, the mean amplitude function for chromatic modulation increased approximately linearly with increasing contrast, whereas the function for luminance modulation increased sharply at low contrasts and saturated at contrasts above approximately 30% for both temporal frequencies, as expected. The patients with RP showed primarily a reduction in R-max with little change in sigma in all testing conditions. The reduction in R-max was equivalent for chromatic modulation and luminance modulation at 5.6 Hz, but was substantially lower for luminance modulation at 11.2 Hz. CONCLUSION. Contrast processing was impaired within both the MC and PC pathways in these patients with RP, but the degree of impairment within the MC pathway depended on temporal frequency. These VEP results are in general agreement with recent psychophysical studies of contrast sensitivity losses in patients with RP, and further they characterize contrast processing deficits in these patients at suprathreshold levels
— id: 56383, year: 2005, vol: 46, page: 2967, stat: Journal Article,

A prospective study of rod and cone function in patients with dominantly inherited, progressive cone dystrophy
Holopigian, K; Greenstein, VC; Seiple, W; Gallardo, JM; Noble, KG; Carr, RE
2005 ;46(Suppl S):4086-4086, Investigative ophthalmology & visual science. IOVS
— id: 56199, year: 2005, vol: 46, page: 4086, stat: Journal Article,

The multifocal visual evoked potential: an objective measure of visual fields?
Seiple, William; Holopigian, Karen; Clemens, Colleen; Greenstein, Vivienne C; Hood, Donald C
2005 Apr;45(9):1155-1163, Vision research
We examined the effects of inter-modal attention and mental arithmetic on Humphrey visual field sensitivity and multifocal visual evoked potential (mfVEP) amplitude. Four normally sighted subjects (ages ranging from 24 to 58 years) participated in this study. Monocular visual field sensitivity was measured under two conditions: (1) standard testing condition and (2) while the subject performed a Paced Auditory Serial Addition Task (PASAT). Monocular mfVEPs were recorded in response to a 60-sector stimulus. The checkerboard pattern in each sector was contrast reversed according to a binary m-sequence. mfVEPs were recorded under two conditions: (1) standard testing conditions and (2) while the subject performed a PASAT. We found that, when compared to the no-task condition, all subjects had locations of significantly reduced Humphrey visual field sensitivities when performing the PASAT. In contrast, there were no significant decreases in mfVEP amplitude in any sector for any of the subjects while performing the PASAT. Our findings indicate that divided attention and ongoing mental processes did not affect the mfVEP. Therefore, the mfVEP provides an objective measure of visual field function that may be useful for some patients with unreliable automated static perimetry results
— id: 51786, year: 2005, vol: 45, page: 1155, stat: Journal Article,

Eye-movement training for reading in patients with age-related macular degeneration
Seiple, William; Szlyk, Janet P; McMahon, Timothy; Pulido, Jose; Fishman, Gerald A
2005 Aug;46(8):2886-2896, Investigative ophthalmology & visual science. IOVS
PURPOSE: To determine whether training oculomotor control, without direct practice in reading sentences, could increase reading speed in patients with age-related macular degeneration (AMD). METHODS: Sixteen patients with AMD participated in the study (age range, 65-87 years; mean, 77). The training program consisted of a series of exercises that were designed to allow the patients to practice eye movements. At the beginning of training, the subjects practiced small horizontal saccades in response to cognitively easy stimuli (e.g., dots). The training then progressed to practicing larger eye movements and then to practicing saccades with single letters, pairs of letters, and three-letter words. Reading of sentences was practiced in only one exercise, during the last session of the 8-week training. RESULTS: The difference between average reading speeds before and after training was 24.7 wpm (difference between medians, 17.9 wpm). The increase in speed was statistically significant (Wilcoxon signed rank test = 124.0, P < 0.001). There was no significant relationship between change in maximum reading speed and ETDRS (Early Treatment Diabetic Retinopathy Study) acuity (r = -0.14, P = 0.76) or between change in maximum reading speed and age (r = 0.25, P = 0.45). CONCLUSIONS: The results indicate that a training curriculum that concentrates on eye-movement control can increase reading speed in patients with AMD. This finding is especially interesting, because the training involved little direct practice in reading sentences but instead concentrated on having subjects practice control of eye positions and eye movements
— id: 57866, year: 2005, vol: 46, page: 2886, stat: Journal Article,

Comprehensive functional vision assessment of patients with North Carolina macular dystrophy (MCDR1)
Szlyk, JP; Paliga, J; Seiple, W; Rabb, MF
2005 JUN ;25(4):489-497, Retina
Purpose: Previous studies indicated abnormal development of fixation toward the optic nerve head in patients with the inherited retinal disease North Carolina macular dystrophy (NCMD). The implication of this development on functional vision and structural characteristics has not been described. Methods: The anatomical characteristics of five NCMD-affected individuals were assessed by measuring the retinal thickness of the macula using optical coherence tomography. The underlying physiologic health of the retina was assessed using the multifocal ERG. Psychophysical assessment of remaining vision in the affected areas was done with a new microperimetry system that measures functional visual acuity at 27 discrete locations and the Humphrey visual field analyzer. Results: All patients had better areas of visual sensitivity toward the nasal macula. Follow-up examination showed no changes in the clinical appearance of the retina. Visual acuities ranged from -0.10 logMAR (Snellen equivalent, approximately 20/16) to 0.50 logMAR (Snellen equivalent, approximately 20/63) in the better eye. No significant changes in visual acuity were found over time. Local multifocal electroretinogram deficits were found in all patients. Patients with grade 2 or 3 disease had large patches of decreased amplitudes and delayed implicit times. Results of the anatomical, electrophysiological, and psychophysical tests were consistent. Conclusion: The electrophysiological and psychophysical deficits found in patients with more severe disease were consistent with an abnormal development of fixation from the anatomical fovea toward the optic nerve head with the placement of the lesion temporal to fixation (into the nasal visual field)
— id: 62381, year: 2005, vol: 25, page: 489, stat: Journal Article,

Use of prisms for navigation and driving in hemianopic patients
Szlyk, JP; Seiple, W; Stelmack, J; McMahon, T
2005 MAR ;25(2):128-135, Ophthalmic & physiological optics
Purpose: (1) To compare the outcomes of orientation and mobility and driving training with Fresnel prisms and the Gottlieb Visual Field Awareness System for patients with homonymous hemianopsia, and (2) To determine whether the patients continue to use the optical enhancement devices at a 2-year follow-up point. Methods: Patients with homonymous hemianopsia were provided with a rehabilitation program where they were fitted with prism lenses and trained to use them for navigation and driving. Telephone interviews were used to obtain information about device usage 2 years following the completion of the training program. Results: Patients' performance was compared with a test-retest criterion in the visual skills areas of recognition, mobility, peripheral detection, scanning, tracking, and visual memory. Patients with hemianopic loss showed improvements in all of the visual skills categories, ranging from the highest improvements of 26% of tasks improved in the mobility category to 13% in the recognition category. The majority of the hemianopic patients reported using the devices at the 2-year follow-up interview. Conclusions: The patients with homonymous hemianopsia showed improvements in visual functioning using prism lenses, although these improvements were smaller than those found in previous studies with central or bilateral peripheral vision loss groups who were trained to use other optical enhancement devices for navigation and driving using a similar curriculum. However, given the evidence of increased risk of accidents for patients with peripheral vision loss, the safety of peripheral enhancement devices for driving must be thoroughly evaluated before their impact on public safety is known
— id: 49015, year: 2005, vol: 25, page: 128, stat: Journal Article,

Assessing responses of the macula in patients with macular holes using a new system measuring localized visual acuity and the mfERG
Szlyk, JP; Vajaranant, TS; Rana, R; Lai, WW; Pulido, JS; Paliga, J; Blair, NP; Seiple, W
2005 MAR-MAY ;110(2-3):181-191, Documenta ophthalmologica
Purpose: To evaluate acuity and multifocal electroretinogram (mfERG) responses from the macula in affected and unaffected fellow eyes of patients with macular holes. Methods: We tested 10 eyes with macular hole and 10 fellow eyes from 11 patients. We Measured local visual acuity thresholds at 27 discrete locations within 21 degrees diameter using the Functional Fundus Imaging System (FFIS), a psychophysical system that measures visual acuity as a function Of Visual Field location, and local ERG responses within 45 degrees diameter using the mfERG. Results: In the affected eyes, the mean FFIS Visual acuity thresholds were significantly elevated within the central 21 degrees diameter area, compared to a group of control eyes. No significant differences were found between the acuities of the fellow eyes compared to those of the control group. The amplitudes of the first positive peak of the mfERG were reduced in the central 7.8 degrees in affected eyes. In the central 2 degrees, 4 Out Of 10 affected eyes showed non-measurable ERG signals. The remaining six eyes showed significantly reduced mean amplitudes, but not delayed implicit times, when compared to the control group. For the fellow eyes, the mean amplitudes of the mfERG and implicit times did not differ from the means of the control eyes. Conclusions: Both local psychophysical and electrophysiological testing demonstrated retinal dysfunction extending beyond the site of the macular holes in some patients (three of the patients had central mfERG amplitudes falling within the normal range)
— id: 63783, year: 2005, vol: 110, page: 181, stat: Journal Article,

Contrast-response properties of magnocellular and parvocellular pathways in retinitis pigmentosa
Alexander, KR; Rajagopalan, AS; Seiple, W; Zemon, VM; Fishman, GA
2004 APR ;45(9):U154-U154, Investigative ophthalmology & visual science. IOVS
— id: 48929, year: 2004, vol: 45, page: U154, stat: Journal Article,

Reliability of multifocal electroretinograms and Humphrey visual field thresholds in patients with retinitis pigmentosa
Clemens, CJ; Seiple, W; Holopigian, K; Carr, RE
2004 APR ;45(9):U577-U577, Investigative ophthalmology & visual science. IOVS
— id: 48934, year: 2004, vol: 45, page: U577, stat: Journal Article,

Atypical multifocal ERG responses in patients with diseases affecting the photoreceptors
Greenstein, V C; Holopigian, K; Seiple, W; Carr, R E; Hood, D C
2004 Nov;44(25):2867-2874, Vision research
The purpose of this study was to investigate atypical multifocal ERG (mfERG) responses for patients with diseases that can affect the photoreceptors. MfERGS were obtained from seven patients with retinitis pigmentosa (RP), three with progressive cone dystrophy (CD) and eight with diabetic retinopathy (DR). Both first- and second-order kernel responses were analyzed. The amplitudes and implicit times of the first-order responses were compared to those obtained from age-similar controls. For the first slice of the second-order response, the root-mean-square (RMS) and the signal-to-noise ratio (SNR) of each response were calculated. Achromatic visual fields were also obtained from each subject. For the three groups of patients, first-order responses with relatively large amplitudes, broad-shaped waveforms and markedly increased implicit times had non-measurable second-order responses. These responses were associated with areas of decreased visual field sensitivity. As RP, CD and DR affect the outer retina, the results are consistent with damage to the outer plexiform layer rather than damage to the inner retina
— id: 92140, year: 2004, vol: 44, page: 2867, stat: Journal Article,

An examination of local ON- and OFF-System responses in patients with progressive cone dystrophy using long duration LED stimulation
Holopigian, K; Wynn, P; Clemens, CJ; Seiple, W; Carr, RE; Hood, DC
2004 APR ;45(9):U586-U586, Investigative ophthalmology & visual science. IOVS
— id: 48935, year: 2004, vol: 45, page: U586, stat: Journal Article,

Rod and cone photoreceptor function in patients with cone dystrophy
Holopigian, Karen; Greenstein, Vivienne C; Seiple, William; Hood, Donald C; Carr, Ronald E
2004 Jan;45(1):275-281, Investigative ophthalmology & visual science. IOVS
PURPOSE: To determine the extent of rod and cone photoreceptor dysfunction in patients with cone dystrophy using psychophysical and electrophysiological tests. METHODS: Ten patients with cone dystrophy participated. Rod and cone system psychophysical thresholds were measured as a function of retinal eccentricity. Bright-flash full-field electroretinograms were obtained under dark-adapted (rod-mediated) and light-adapted (cone-mediated) conditions. The a-wave data were fitted with a model based on photopigment transduction to obtain values for log Rmax (maximum response) and log S (sensitivity). b-Wave parameters were also examined by fitting a nonlinear, saturating function (the Naka-Rushton equation) to the rod-mediated responses. Oscillatory potentials were measured to the cone-mediated high-intensity flashes. RESULTS: On average, the rod-mediated psychophysical thresholds were elevated by 0.5 log unit. These threshold elevations did not differ significantly with retinal eccentricity. In contrast, cone-mediated psychophysical thresholds were elevated up to 3.0 log units. Threshold elevation was greatest in the central retinal locations. For rod-mediated conditions, the a-wave Rmax parameter was significantly reduced in three patients; the a-wave log S parameter was within normal limits. The rod-mediated b-wave Rmax parameter was reduced in six patients; log k was abnormal in one patient. For cone-mediated conditions, the a-wave Rmax parameter was reduced in six patients and the a-wave log S parameter was reduced in two patients. The cone system oscillatory potentials were abnormal in nine patients. CONCLUSIONS: Patients with cone dystrophy show different patterns of psychophysical rod versus cone system sensitivity losses with retinal eccentricity. The full-field electrophysiological data indicate that most of the patients had abnormal cone photoreceptor function. Some patients also showed rod photoreceptor abnormalities. The rod system changes were smaller than the cone system changes
— id: 42630, year: 2004, vol: 45, page: 275, stat: Journal Article,

Eye movement training for reading in patients with age-related macular degeneration
Seiple, WH; Szlyk, JP
2004 APR ;45(9):U654-U654, Investigative ophthalmology & visual science. IOVS
— id: 48938, year: 2004, vol: 45, page: U654, stat: Journal Article,

Test-retest reliability of the multifocal electroretinogram and humphrey visual fields in patients with retinitis pigmentosa
Seiple, William; Clemens, Colleen J; Greenstein, Vivienne C; Carr, Ronald E; Holopigian, Karen
2004 Nov;109(3):255-272, Documenta ophthalmologica
We examined the reliability of Humphrey visual field thresholds and multifocal electroretinogram (mfERG) amplitudes and timing in a group of patients with Retinitis Pigmentosa (RP). Eight patients with RP and seven control subjects were tested five times: at baseline (visit #0), at three weekly follow-up visits (visits #1 - #3), and at three months (visit #4). For the Humphrey thresholds, differences between dB values on repeat visits were obtained. Differences between log values on repeat visits were calculated for mfERG amplitude and implicit time. We used the standard deviations of these difference scores as a measure of reliability and the means of the difference scores as a measure of progression. We found that the majority of the patients' repeat data were more variable than that of the control subjects for both the Humphrey and mfERG. We found no single factor that predicted the magnitude, or the variance, of the SD of differences scores for the patients. We recommend that each patient's reliability be assessed individually. Ultimately, the choice of an outcome measure must be guided by its reliability, as well as its ability to assess the visual function of interest
— id: 55997, year: 2004, vol: 109, page: 255, stat: Journal Article,

Multidimensional visual field maps: Relationships among local psychophysical and local electrophysiological measures
Seiple, William; Holopigian, Karen; Szlyk, Janet P; Wu, Carolyn
2004 May;41(3A):359-372, Journal of rehabilitation research & development
Multidimensional psychophysical and electrophysical maps of the central retina are essential for assessing the functioning of the diseased retina. In this study, grating acuity, contrast sensitivity, duration for letter identification, multifocal electroretinograms, and Humphrey visual field thresholds were measured at equivalent positions throughout the central 20 degrees . We found that the rates of sensitivity loss were not equivalent for all psychophysical measures. The rate of loss in the duration required for letter identification as a function of eccentricity was the steepest, followed by acuity and contrast sensitivity. The rate of loss in luminance sensitivity as measured in the Humphrey visual field was the shallowest. The pattern of losses also varied across meridians. Specifically, the rate of loss as a function of eccentricity was highest in the vertical meridian and lowest in the horizontal meridian. These maps and the correlations among measures as a function of retinal position serve as a baseline so that we can examine disease effects throughout the retina. In addition, the development of vision rehabilitation programs focused on eccentric viewing training should consider the differential sensitivities of the peripheral retina
— id: 46898, year: 2004, vol: 41, page: 359, stat: Journal Article,

Relationship of retinal structural and clinical vision parameters to driving performance of diabetic retinopathy patients
Szlyk, JP; Mahler, CL; Seiple, W; Vajaranant, TS; Blair, NP; Shahidi, M
2004 MAY-JUN ;41(3A):347-357, Journal of rehabilitation research & development
This study identifies clinical vision measures or retinal structural measures associated with the driving performance of diabetic retinopathy patients. Twenty-five licensed drivers with diabetic retinopathy (median age, 53 years; range, 34-72 years) completed clinical tests (visual acuity, letter contrast sensitivity, and Humphrey 30-2 visual fields) and structural examinations (retinal thickness analysis and fundus photograph grading of retinopathy and laser scarring). Driving performance was assessed with an interactive driving simulator and a driving history questionnaire. Increased retinal thickness was significantly correlated with a higher frequency of simulator accidents and near accidents. Laser scar grades significantly correlated with steeper brake-response slopes, increased brake-pressure standard deviation (SD), and longer response times. Subjects with focal laser scars had significantly higher average brake-pedal pressure and brake-pressure SD than subjects without focal laser scars. Retinal thickness and laser scarring correlated with driving simulator performance in subjects with diabetic retinopathy
— id: 46478, year: 2004, vol: 41, page: 347, stat: Journal Article,

Detection of changes in brain activation by functional magnetic resonance imaging (fMRI) in macular degeneration patients following reading rehabilitation
Szlyk, JP; Nazeer, U; Seiple, W; Bloom, JN; Pulido, JS; Thulborn, KR
2004 APR ;45(9):U653-U653, Investigative ophthalmology & visual science. IOVS
— id: 48937, year: 2004, vol: 45, page: U653, stat: Journal Article,

Local analysis of visual dysfunction and retinal structural alteration in non-exudative age-related macular degeneration
Vajaranant, TS; Seiple, W; Szlyk, JP; Paliga, J; Shahidi, M; Blair, NP
2004 APR ;45(9):U69-U69, Investigative ophthalmology & visual science. IOVS
— id: 48927, year: 2004, vol: 45, page: U69, stat: Journal Article,

M-versus P-function: Relationship to visual field loss in patients with open angle glaucoma
Badr, AA; Zemon, VM; Greenstein, VC; Clemens, CJ; Holopigian, K; Seiple, W
2003 MAY ;44(3):U5-U5, Investigative ophthalmology & visual science. IOVS
— id: 55412, year: 2003, vol: 44, page: U5, stat: Journal Article,

Local ON and OFF system responses in patients with progressive cone dystrophy
Holopigian, K; Seiple, W; Clemens, CJ; Rozenbaum, I; Carr, RE
2003 MAY ;44(3):U105-U105, Investigative ophthalmology & visual science. IOVS
— id: 55417, year: 2003, vol: 44, page: U105, stat: Journal Article,

The effect of variably tinted spectacle lenses on visual performance in cataract subjects
Naidu, Srilata; Lee, Jason E; Holopigian, Karen; Seiple, William H; Greenstein, Vivienne C; Stenson, Susan M
2003 Jan;29(1):17-20, Eye & contact lens
PURPOSE: A body of clinical and laboratory evidence suggests that tinted spectacle lenses may have an effect on visual performance. The aim of this study was to quantify the effects of spectacle lens tint on the visual performance of 25 subjects with cataracts. METHODS: Cataracts were scored based on best-corrected acuity and by comparison with the Lens Opacity Classification System (LOCS III) plates. Visual performance was assessed by measuring contrast sensitivity with and without glare (Morphonome software version 4.0). The effect of gray, brown, yellow, green and purple tinting was evaluated. RESULTS: All subjects demonstrated an increase in contrast thresholds under glare conditions regardless of lens tint. However, brown and yellow lens tints resulted in the least amount of contrast threshold increase. Gray lens tint resulted in the largest contrast threshold increase. CONCLUSIONS: Individuals with lenticular changes may benefit from brown or yellow spectacle lenses under glare conditions
— id: 39215, year: 2003, vol: 29, page: 17, stat: Journal Article,

Reliability of perimetry: Measures of acuity, contrast sensitivity, and luminance detection
Nam, JN; Kirzhner, M; Clemens, CJ; Holopigian, K; Seiple, W
2003 MAY ;44(19):U671-U671, Investigative ophthalmology & visual science. IOVS
— id: 55467, year: 2003, vol: 44, page: U671, stat: Journal Article,

Multifocal electroretinography as a function of age: the importance of normative values for older adults
Seiple, William; Vajaranant, Thasarat S; Szlyk, Janet P; Clemens, Colleen; Holopigian, Karen; Paliga, Jennifer; Badawi, David; Carr, Ronald E
2003 Apr;44(4):1783-1792, Investigative ophthalmology & visual science. IOVS
PURPOSE: To determine the influence of age on local electroretinographic responses in humans. METHODS: Multifocal electroretinograms (mfERGs) were obtained from 62 normally sighted subjects ranging in age from 21 to 81 years. A stimulus array of 103 scaled hexagons was used to measure electrical signals within a retinal area approximately 46 degrees in diameter. Commonly reported mfERG methods were used to quantify the responses: peak-to-peak amplitudes and implicit times, scalar product amplitude, and amplitude and time scales derived from the algorithm of Hood and Li, published in 1997. RESULTS: Regression analysis showed significant linear relationships of amplitude and timing measures with age. The rates of losses were 10.5% per decade for peak-to-peak amplitude, 11.7% per decade for scalar product amplitude, and 9.5% per decade for a-scale. The rate of amplitude reduction was highest in the central 3 degrees. Age had less influence on implicit time measures. The rates of timing losses were 1.4% per decade for the N1 component and 1.0% per decade for both the P1 component and the t-scale measure. Using predicted interval ranges, the age was calculated at which 50% of the expected values would fall below the lower 95% prediction interval band of younger subjects. CONCLUSIONS: The age-associated mfERG alterations are presented to emphasize the importance of appropriate normative data in interpretation of mfERGs
— id: 39262, year: 2003, vol: 44, page: 1783, stat: Journal Article,

Test-retest reliability of psychophysical and electrophysiological perimetric measures in patients with retinitis pigmentosa
Clemens, CJ; Kirzhner, M; Holopigian, K; Seiple, W; Greenstein, VC; Carr, RE
2002 MAY ;43(3):U254-U254, Investigative ophthalmology & visual science. IOVS
— id: 55483, year: 2002, vol: 43, page: U254, stat: Journal Article,

Local cone and rod system function in progressive cone dystrophy
Holopigian, Karen; Seiple, William; Greenstein, Vivienne C; Hood, Donald C; Carr, Ronald E
2002 Jul;43(7):2364-2373, Investigative ophthalmology & visual science. IOVS
PURPOSE: To compare the patterns of local cone and rod system impairment in patients with progressive cone dystrophy (CD) using psychophysical and electrophysiological techniques. METHODS: Local cone system function was assessed by measuring cone system thresholds (visual fields) and cone-mediated multifocal electroretinograms (mfERGs). Rod system function was assessed by measuring rod system thresholds (visual fields) and rod-mediated mfERGs. The results in a group of eight patients with CD were compared with those in an age-similar control group. RESULTS: All the patients had abnormal cone system visual field thresholds and cone-mediated mfERGs. Cone system psychophysical thresholds were elevated for targets presented within the central 10 degrees, but were within normal limits for targets at peripheral locations. Cone-mediated mfERG measures of amplitude scale and time scale were abnormal for most of the hexagons tested. Most of the rod-mediated psychophysical thresholds and mfERGs were within normal limits. Rod system losses tended to be patchy and scattered throughout the area tested. CONCLUSIONS: There was poor correspondence among local measures of cone and rod system losses in these patients with CD. The results suggest that the spatial pattern of cone system losses in this disease differs from the spatial pattern of rod system losses
— id: 39621, year: 2002, vol: 43, page: 2364, stat: Journal Article,

Effect of variable tinted spectacle lenses on visual performance in control subjects
Lee, Jason E; Stein, Jonathan J; Prevor, Meredith B; Seiple, William H; Holopigian, Karen; Greenstein, Vivienne C; Stenson, Susan M
2002 Apr;28(2):80-82, CLAO journal (Contact Lens Association of Ophthalmologists)
PURPOSE: To evaluate quantitatively the effects of tinted spectacle lenses on visual performance in individuals without visual pathology. METHODS: Twenty-five subjects were assessed by measuring contrast sensitivity with and without glare. Gray, brown, yellow, green, purple, and blue lens tints were evaluated. Measurements were repeated with each lens tint and with a clear lens, and the order was counterbalanced within and between subjects. Glare was induced with a modified brightness acuity tester. RESULTS: All subjects demonstrated an increase in contrast thresholds under glare conditions for all lens tints. However, purple and blue lens tints resulted in the least amount of contrast threshold increase; the yellow lens tint resulted in the largest contrast threshold increase. CONCLUSIONS: Purple and blue lens tints may improve contrast sensitivity in control subjects under glare conditions
— id: 37709, year: 2002, vol: 28, page: 80, stat: Journal Article,

Relationships among luminance, acuity, contrast, and electrophysiological perimetry in patients with retinitis pigmentosa
Seiple, WH; Clemens, C; Holopigian, K; Greenstein, V; Carr, R
2002 MAY ;43(3):U254-U254, Investigative ophthalmology & visual science. IOVS
— id: 55482, year: 2002, vol: 43, page: U254, stat: Journal Article,

The spatial distribution of selective attention assessed using the multifocal visual evoked potential
Seiple, William; Clemens, Colleen; Greenstein, Vivienne C; Holopigian, Karen; Zhang, Xian
2002 Jun;42(12):1513-1521, Vision research
To determine the manner in which attention is distributed among numerous locations in the visual space, we used a multifocal recording technique that allowed simultaneous recordings of evoked cortical activity from 12 visual field areas out to 23.6 degrees. We found that multifocal visual evoked potential (mfVEP) amplitude was larger when a region of visual space was attended than when it was not attended. The magnitude of this effect was inversely related to visual field eccentricity and there was no attention-related modulation of VEP amplitude for the most eccentric region. In addition, we found that mfVEP amplitudes in the regions contiguous to the attended region could also be larger, depending upon their spatial relationship to the attended region. Specifically, amplitudes in more central regions on the 'meridian of attention' were larger when the subject attended anywhere along that meridian
— id: 39622, year: 2002, vol: 42, page: 1513, stat: Journal Article,

A method for comparing psychophysical and multifocal electroretinographic increment thresholds
Seiple, William; Greenstein, Vivienne C; Holopigian, Karen; Carr, Ronald E; Hood, Donald C
2002 Jan;42(2):257-269, Vision research
The multifocal electroretinogram (mfERG) has been commonly used as a method for obtaining objective visual fields. Although qualitative comparisons have been good, quantitative comparisons between the results from mfERG and the results from Humphrey Visual Field Analyser (HVFA) have found variable degrees of agreement depending upon the mfERG response parameter examined and/or the disease studied. Lack of agreement may be due to differences in methodology, differences in the sites of response generation, and/or differences derived from comparing suprathreshold versus threshold responses. In addition, the two procedures are performed at different levels of adaptation. We developed an approach for matching stimulus parameters and compared mfERG and psychophysical thresholds to assess the effects of technique and level of adaptation on the two responses. Psychophysical and mfERG thresholds were obtained as a function of the adaptation level (1.5-4.0 log td) and retinal location. The derived increment threshold-versus-intensity functions for both measures were fitted using the equation logT=logT(0)+log((A+A(0))/A(0))(n). We found that the values of A(0) for the mfERG data were one log unit higher than those for the psychophysical data. In addition, the value of the slope (n) for the mfERG data was shallower (0.8) than that of the psychophysical data (1.0). Predictions were made about comparisons of HVFA threshold and mfERG amplitude data in patients with retinal disease based upon a two-site model of adaptation. The data for some groups of patients could be best-fitted with a model of a disease acting at a site distal to all gain changes, whereas data from other patients were best fitted with a model of a disease acting at a site proximal to all retinal gain. The relationship between the Humphrey visual field threshold losses and mfERG amplitude reductions depends upon the site and mechanism of a particular disease process and the model of retinal gain assumed. In no case is a one-to-one relationship between the losses in the two measures predicted
— id: 39725, year: 2002, vol: 42, page: 257, stat: Journal Article,

Detection using the multifocal electroretinogram of mosaic retinal dysfunction in carriers of X-linked retinitis pigmentosa
Vajaranant, TS; Seiple, W; Szlyk, JP; Fishman, GA
2002 Mar;109(3):560-568, Ophthalmology
Purpose: To examine whether a mosaic pattern of retinal dysfunction in obligate carriers of X-linked retinitis pigmentosa (XLRP) could be observed in local electroretinographic responses obtained with the multifocal electroretinogram (mfERG). Design: Prospective observational case series. Participants: Five obligate carriers of XLRP (mean age, 53.2 years) were recruited into the study. Methods: Examination of each subject included a complete ocular examination, Humphrey visual field, standard full-field electroretinogram (ERG), and mfERG testing. For the mfERG, we used a 103-scaled hexagonal stimulus array that subtended a retinal area of approximately 400 in diameter. The amplitudes and implicit times in each location for the mfERG was compared with the corresponding value determined for a group of normally sighted, age-corrected control subjects. Main Outcome Measures: Mapping of 103 local electroretinographic response amplitudes and implicit times within the central 400 with the multifocal electroretinogram. Results: Localized regions of reduced mfERG amplitudes and/or delayed implicit times were found in four of five carriers. In one of these four carriers, a mosaic pattern of mfERG dysfunction was present even in the absence of any clinically apparent retinal changes, retinal sensitivity losses on Humphrey field testing, or abnormal full-field cone ERG responses. However, one carrier with a typical tapetal-like reflex demonstrated no deficit on any functional tests. Conclusions: The mfERG demonstrated patchy areas of retinal dysfunction in some carriers of XLRP. This mosaic pattern of dysfunction may be observed in some patients with a normal- appearing fundus, normal psychophysical thresholds, and normal amplitude and implicit time full-field ERG cone responses. Ophthalmology 2002;109:560-568 (C) 2002 by the American Academy of Ophthalmology
— id: 27529, year: 2002, vol: 109, page: 560, stat: Journal Article,

Localized retinal dysfunction in central serous chorioretinopathy as measured using the multifocal electroretinogram
Vajaranant, TS; Szlyk, JP; Fishman, GA; Gieser, JP; Seiple, W
2002 Jul;109(7):1243-1250, Ophthalmology
Purpose: To determine the extent of electrophysiologic dysfunction in patients with central serous chorioretinopathy (CSC). Design: Prospective observational case series. Participants; Six patients with unilateral CSC (mean age, 40 years) were recruited into the study. Methods: Six patients with CSC underwent multifocal electroretinogram (mfERG) testing on both their clinically affected and opposite uninvolved eyes using the VERIS System, with a stimulus array of 103 scaled hexagons. The first positive peak responses were analyzed within six concentric ring annuli centered on the fovea. Amplitudes and implicit times were compared with those of an age-similar control group. Main Outcome Measures: Local electroretinographic response amplitudes and implicit times within the central 40degrees with the mfERG. Results: All the clinically uninvolved eyes showed mfERG amplitudes and implicit times within the normal range throughout the central 40degrees of the retina. All six eyes with CSC showed reduced amplitudes and/or delayed implicit times that were limited to the regions of the macula in which clinical changes associated with CSC were apparent. Conclusions: We observed electroretinographic changes only in the clinically affected eyes, and these were limited to regions with ophthalmoscopically apparent fundus changes. Our findings do not support the conclusion that functional impairment, as measured by the mfERG, in eyes with CSC extends beyond clinically observed fundus changes. We did not observe abnormal mfERG responses in the clinically normal eyes of such patients. Ophthalmology 2002;109:1243-1250 (C) 2002 by the American Academy of Ophthalmology
— id: 30697, year: 2002, vol: 109, page: 1243, stat: Journal Article,

Localized attention assessed using the multifocal visual evoked potential
Clemens, CJ; Seiple, W; Holopigian, K; Greenstein, VC; Zhang, X
2001 MAR 15 ;42(4):S408-S408, Investigative ophthalmology & visual science. IOVS
— id: 54975, year: 2001, vol: 42, page: S408, stat: Journal Article,

An examination of visual evoked potential increment thresholds as a function of retinal eccentricity
Donsoff, I; Holopigian, K; Rubbani, S; Seiple, W
2001 MAR 15 ;42(4):S789-S789, Investigative ophthalmology & visual science. IOVS
— id: 54990, year: 2001, vol: 42, page: S789, stat: Journal Article,

Multifocal ERG (M-ERG) testing in patients with central serous chorioretinopathy
Fishman, GA; Vajaranant, TS; Seiple, W; Szlyk, JP; Gieser, J
2001 MAR 15 ;42(4):S684-S684, Investigative ophthalmology & visual science. IOVS
— id: 54985, year: 2001, vol: 42, page: S684, stat: Journal Article,

Retinal pigment epithelial dysfunction in patients with pigment dispersion syndrome: implications for the theory of pathogenesis
Greenstein VC; Seiple W; Liebmann J; Ritch R
2001 Sep;119(9):1291-1295, Archives of ophthalmology
OBJECTIVE: To test the hypothesis that the retinal pigment epithelial/photoreceptor complex is affected in patients with pigment dispersion syndrome and/or in patients with pigmentary glaucoma. METHODS: Electro-oculograms were recorded from patients with pigment dispersion syndrome, pigmentary glaucoma, ocular hypertension, and primary open-angle glaucoma and from control subjects. Electro-oculograms were recorded during 15 minutes of dark adaptation followed by 15 minutes of light adaptation. For each subject, dark-trough amplitudes, dark-trough latencies, light-peak amplitudes, light-peak latencies, and ratios of the light-peak amplitude to the dark-trough amplitude (Arden ratios) were calculated. RESULTS: A 1-way analysis of variance of the Arden ratios indicated significant differences among the groups of subjects. Results of a post hoc Newman-Keuls test revealed that the mean Arden ratios of patients with pigment dispersion syndrome and patients with pigmentary glaucoma were significantly lower than the mean ratios of the controls, the patients with primary open-angle glaucoma, and those with ocular hypertension. CONCLUSIONS: The results provide support for the hypothesis that the integrity of the retinal pigment epithelial/photoreceptor complex is affected in patients with pigment dispersion syndrome and in those with pigmentary glaucoma. Congenital and/or structural abnormalities of the retinal pigment epithelial/photoreceptor complex should be considered when models of the etiology of pigment dispersion syndrome are proposed
— id: 26669, year: 2001, vol: 119, page: 1291, stat: Journal Article,

Local cone and rod system function in patients with retinitis pigmentosa
Holopigian K; Seiple W; Greenstein VC; Hood DC; Carr RE
2001 Mar;42(3):779-788, Investigative ophthalmology & visual science. IOVS
PURPOSE. To compare local cone and rod system function in patients with retinitis pigmentosa (RP) using electrophysiological and psychophysical techniques. METHODS. Cone-mediated multifocal electroretinograms (M-ERGs), cone system threshold visual fields, rod-mediated M-ERGs, and rod system threshold visual fields were measured in seven patients with RP. RESULTS. All the patients had normal cone system visual field thresholds and normal cone-mediated M-ERG implicit times within the central 5 degrees. Both cone-mediated responses were abnormal at some peripheral retinal locations. There were significant correlations among cone system amplitude, timing, and visual field loss. All the patients had some retinal areas where the rod-mediated M-ERG amplitudes were not measurable. In areas where they were measurable, these rod-mediated M-ERG responses were often within normal limits for amplitude and timing. In contrast to the cone system data, there were no significant relationships between rod-mediated M-ERG measures and rod system threshold elevations. The cone and rod system psychophysical thresholds showed regional correspondence; the amplitude-scale and time-scale measures of the M-ERG did not. CONCLUSIONS. The results indicate that there was better local correspondence between psychophysical and electrophysiological measures in the cone system than in the rod system in patients with RP. In addition, the psychophysical measures of cone and rod system function showed better correspondence than did the electrophysiological measures
— id: 26783, year: 2001, vol: 42, page: 779, stat: Journal Article,

Sites of cone and rod system loss in patients with progressive cone dystrophy
Holopigian, K; Greenstein, VC; Wu, C; Seiple, W; Hood, DC; Carr, RE
2001 MAR 15 ;42(4):S71-S71, Investigative ophthalmology & visual science. IOVS
— id: 54969, year: 2001, vol: 42, page: S71, stat: Journal Article,

Variable tinted spectacle lenses: a comparison of aesthetics and visual preference
Huang L; Seiple W; Park RI; Greenstein VC; Holopigian K; Naidu SS; Stenson SM
2001 Jul;27(3):121-124, CLAO journal (Contact Lens Association of Ophthalmologists)
PURPOSE: To determine the correlation between the aesthetics of lens tints preferred for cosmesis and lens tints preferred for viewing. METHODS: Thirty-five subjects (mean age: 25; 49% male, 51% female) with no significant ocular pathology participated in the study. Median visual acuity was 20/20. Color vision testing was performed on each subject using Ishihara plates, and those with abnormal scores were excluded from the study. Subjects were shown nine pre-selected tinted lenses (50% transmittance) of variable wavelengths. These lenses were mounted on two separate color backgrounds, one white and the other approximating their skin tone. Subjects were asked to choose from each background which tinted lens they would most prefer to wear and which lens they would least prefer to wear. The subjects were then shown a series of eight pictures (four nature photographs and four paintings) with different dominant wavelengths. Subjects were asked to grade the aesthetic effect of a clear lens and each of the nine tinted lenses on the appearance of the pictures. Chromaticity coordinates were calculated for each lens and picture. RESULTS: The blue lens was the most frequently chosen preferred lens to wear, followed by green, purple, and gray. The least preferred lenses were yellow, brown, and pink. For viewing the nature photographs, the clear lens was preferred over any of the tinted lenses. For viewing the paintings, the purple lens was most preferred. The yellow lens was least preferred for both photographs and paintings. CONCLUSIONS: Younger individuals with no significant ocular pathology preferred viewing both nature photographs and paintings through tinted lenses that did not, or only slightly, altered the chromaticity of the image. Whereas a clear lens was favored over the tinted lenses for viewing the photographs, some tinted lenses (purple and pink) were preferred for viewing paintings. There was no correlation between the most favored lens tint chosen based purely on cosmesis and the most favored lens tint based on viewing preference. However, the least preferred lens tint for cosmesis and viewing was yellow
— id: 26629, year: 2001, vol: 27, page: 121, stat: Journal Article,

Fundamental mapping using the functional fundus imaging system and the Multifocal Electroretinogram in patients with North Carolina Macular Dystrophy
Paliga, J; Szlyk, JP; Seiple, W; Vajaranant, TS; Rabb, MF
2001 MAR 15 ;42(4):S70-S70, Investigative ophthalmology & visual science. IOVS
— id: 54968, year: 2001, vol: 42, page: S70, stat: Journal Article,

Duration thresholds for target detection and identification in the peripheral visual field
Seiple W; Holopigian K; Shnayder Y; Szlyk JP
2001 Mar;78(3):169-176, Optometry & vision science
PURPOSE: In the current study, we measured threshold duration required to perform the tasks of letter identification, letter detection, grating orientation discrimination, and symmetry detection of targets presented as a function of retinal eccentricity. METHODS: Targets were presented in the nasal visual field on the horizontal meridian at eccentricities ranging from 0 degree to 22 degrees. Threshold duration was calculated using a modified staircase procedure. RESULTS: We found that for the task of letter identification, the rate of duration sensitivity loss was independent of the letter size. In contrast, for the tasks of letter detection, grating discrimination, and symmetry detection, the rate of loss was greater for smaller targets than for larger targets. CONCLUSION: At equivalent target sizes, letter identification always demonstrated the steepest decline in duration sensitivity with increasing eccentricity. This might be the case if the final stages of the identification process are rate limiting. It was hoped that by quantifying duration sensitivity of the peripheral retina, more appropriate temporal stimuli could be used in rehabilitation programs that train reading using eccentric preferred retina loci in patients with advanced macular disease
— id: 20698, year: 2001, vol: 78, page: 169, stat: Journal Article,

Lateral spread of adaptation as measured with the multifocal electroretinogram
Seiple W; Vajaranant TS; Pepperberg DR; Szlyk JP
2001 Sep-Oct;18(5):687-694, Visual neuroscience
We examined whether lateral spread of adaptation can be observed in the electroretinogram in humans. Specifically, we tested whether the luminance level of a surrounding, nonmodulated annulus affects the multifocal electroretinogram (ERG) response of a modulated central area. Multifocal electroretinograms were recorded in response to an array of 37 unscaled hexagons subtending a retinal area of 38 deg x 35 deg. Responses were recorded in six control subjects. In the first series of experiments, only the center hexagon was modulated, while the surrounding 36 hexagons were held constant at either 0.45, 172, or 340 cd/m2. In a subsequent series of control experiments, modulation depth of the center hexagon was varied and the proximity of the surrounding hexagon systematically altered. For the center-modulated condition, response amplitude and implicit time for the first-order kernel response significantly decreased as a function of increasing surround luminance. Control experiments demonstrated that the effect of the surround illumination was not due to scattered light but was influenced by the proximity of the surrounding annulus. These results demonstrate that lateral adaptation influences can be measured using the multifocal ERG
— id: 39456, year: 2001, vol: 18, page: 687, stat: Journal Article,

Local measures of psychophysical sensitivity, visual acuity and electroretinographic function in patients with age-related macular degeneration
Seiple, W; Szlyk, JP; Paliga, J; Vajaranant, TS; Pulido, JS; Blair, NP
2001 MAR 15 ;42(4):S707-S707, Investigative ophthalmology & visual science. IOVS
— id: 54986, year: 2001, vol: 42, page: S707, stat: Journal Article,

Detection of mosaic retinal dysfunction in carriers of X-linked recessive retinitis pigmentosa using the multifocal electroretinogram
Vajaranant, TS; Seiple, W; Szlyk, JP; Fishman, GA
2001 MAR 15 ;42(4):S73-S73, Investigative ophthalmology & visual science. IOVS
— id: 54970, year: 2001, vol: 42, page: S73, stat: Journal Article,

Retinal function in diabetic macular edema after focal laser photocoagulation
Greenstein VC; Chen H; Hood DC; Holopigian K; Seiple W; Carr RE
2000 Oct;41(11):3655-3664, Investigative ophthalmology & visual science. IOVS
PURPOSE: To assess the effects of focal photocoagulation on retinal function in the macular and perimacular areas in patients with diabetes who have clinically significant macular edema. METHODS: Eleven patients were assessed after focal laser treatment. Multifocal electroretinogram (ERG) and full-field ERG techniques were used to evaluate the effects of treatment on macular, paramacular, and peripheral retinal function. A modified visual field technique was used to obtain local threshold fields. The posttreatment results were compared with pretreatment results. Changes in local ERG response amplitudes and implicit times were calculated for each patient and presented as difference fields. The changes in local ERG responses were compared with the changes in local field sensitivity. RESULTS: After treatment, the results of the psychophysical tests suggested little or no change in visual function, but changes in retinal function were observed with the multifocal ERG technique. Local ERG responses showed increases in implicit time and decreases in amplitude, compared with pretreatment values. Timing was affected more than amplitude. CONCLUSIONS: The results suggest that focal treatment produces changes in retinal function, and these changes are not restricted to the treated macular area
— id: 39554, year: 2000, vol: 41, page: 3655, stat: Journal Article,

The nature and extent of retinal dysfunction associated with diabetic macular edema
Greenstein VC; Holopigian K; Hood DC; Seiple W; Carr RE
2000 Oct;41(11):3643-3654, Investigative ophthalmology & visual science. IOVS
PURPOSE: To evaluate the nature and extent of retinal dysfunction in the macular and surrounding areas that occurs in patients with diabetes with clinically significant macular edema (CSME). METHODS: Eleven patients were evaluated before focal laser treatment. Multifocal electroretinogram (ERG) and full-field ERG techniques were used to assess the effects of diabetic retinopathy and CSME on macular, paramacular, and peripheral retinal function. A modified visual field technique was used to obtain local threshold fields. The relationship between local sensitivity changes and local ERG changes was determined. RESULTS: Local ERG responses were significantly delayed and decreased in amplitude, and timing changes were observed in a larger area of the retina than amplitude changes. Visual field deficits were similarly widespread with marked sensitivity losses occurring in retinal areas with normal ERG amplitudes and in areas that appeared to be free of fundus abnormalities. Despite this similarity and the finding that retinal areas with elevated thresholds have timing delays, timing delays were not good predictors of the degree of threshold elevation. CONCLUSIONS: The results demonstrate the widespread nature of timing deficits and visual field deficits that are associated with CSME
— id: 39555, year: 2000, vol: 41, page: 3643, stat: Journal Article,

Electrophysiologic assessment of photoreceptor function in patients with primary open-angle glaucoma
Holopigian K; Greenstein VC; Seiple W; Hood DC; Ritch R
2000 Apr;9(2):163-168, Journal of glaucoma
PURPOSE: Electroretinograms to high-intensity flashes were obtained to determine the extent of rod and cone photoreceptor and postreceptor dysfunction in patients with primary open-angle glaucoma. METHODS: Full-field flash electroretinograms were obtained using brief high-intensity flashes. Dark-adapted (rod-dominated) and light-adapted (cone-dominated) electroretinogram responses were recorded to a 'white' light as a function of flash intensity. The a-wave data were fitted with a model based on photopigment transduction to obtain values for the parameters of log Rmax (the maximum response) and log S (sensitivity). Oscillatory potentials were measured to the cone-dominated high-intensity flashes. Standard clinical 30 Hz flicker electroretinogram responses were recorded using a Grass photostimulator. RESULTS: Analysis of rod and cone a-wave data showed that log Rmax and log S values were within the normal range in nearly all of the patients. For some patients, oscillatory potentials were delayed beyond the normal range. CONCLUSION: Our results provide little evidence for widespread photoreceptor abnormalities in primary open-angle glaucoma
— id: 11735, year: 2000, vol: 9, page: 163, stat: Journal Article,

Are the differences between threshold visual fields and multifocal ERGs due to adaptation level?
Holopigian, K; Seiple, W; Greenstein, VC; Hood, DC; Carr, RE
2000 MAR 15 ;41(4):S892-S892, Investigative ophthalmology & visual science. IOVS
— id: 54624, year: 2000, vol: 41, page: S892, stat: Journal Article,

A comparison of psychophysical and multifocal electroretinographic increment thresholds as a function of retinal location
Seiple, W; Holopigian, K; Greenstein, VC; Hood, DC
2000 MAR 15 ;41(4):S496-S496, Investigative ophthalmology & visual science. IOVS
— id: 54616, year: 2000, vol: 41, page: S496, stat: Journal Article,

Lateral spread of adaptation measured using the multifocal ERG
Vajaranant, TS; Seiple, W; Pepperberg, DR; Szlyk, JP; Snyder, C
2000 MAR 15 ;41(4):S496-S496, Investigative ophthalmology & visual science. IOVS
— id: 54615, year: 2000, vol: 41, page: S496, stat: Journal Article,

Does pigment dispersion syndrome affect retinal pigment epithelial function?
Chen, H; Greenstein, VC; Seiple, W; Park, R; Ritch, R
1999 MAR 15 ;40(4):S81-S81, Investigative ophthalmology & visual science. IOVS
— id: 54089, year: 1999, vol: 40, page: S81, stat: Journal Article,

Functional peripheral visual performance in patients with RP
Holopigian, K; Seiple, W; Wu, C; Carr, RE
1999 May 9-14;40(4):S718-S718, Investigative ophthalmology & visual science. IOVS
— id: 34141, year: 1999, vol: 40, page: S718, stat: Journal Article,

Identifying inner retinal contributions to the human multifocal ERG
Hood, D C; Greenstein, V; Frishman, L; Holopigian, K; Viswanathan, S; Seiple, W; Ahmed, J; Robson, J G
1999 Jun;39(13):2285-2291, Vision research
Contributions to the multifocal electroretinogram (ERG) from the inner retina (i.e. ganglion and amacrine cells) were identified by recording from monkeys before and after intravitreal injections of n-methyl DL aspartate (NMDLA) and/or tetrodotoxin (TTX). Components similar in waveform to those removed by the drugs were identified in the human multifocal ERG if the stimulus contrast was set at 50% rather than the typically employed 100% contrast. These components were found to be missing or diminished in the records from some patients with glaucoma and diabetes, diseases which affect the inner retina
— id: 93713, year: 1999, vol: 39, page: 2285, stat: Journal Article,

Retinotopic distribution of the temporal aspects of letter identification
Seiple, W; Wu, C; Holopigian, K; Szlyk, J; Shnayder, Y; Chen, H
1999 May 9-14;40(4):S34-S34, Investigative ophthalmology & visual science. IOVS
— id: 34142, year: 1999, vol: 40, page: S34, stat: Journal Article,

Multifocal rod electroretinograms
Hood DC; Wladis EJ; Shady S; Holopigian K; Li J; Seiple W
1998 Jun;39(7):1152-1162, Investigative ophthalmology & visual science. IOVS
PURPOSE: To assess the feasibility of obtaining reliable multifocal rod electroretinograms (ERGS) and to compare them to full-field ERGs. METHODS: Multifocal rod ERGs were recorded using a stimulus array of 61 hexagons. The minimum number of dark, blank frames between flashes was varied from 0 (a minimum of 13.3 msec between flashes) to 21 (a minimum of 293 msec between flashes). Full-field ERGs were obtained using trains of flashes designed to simulate the multifocal sequences. Flashes were blue (W47B), except in a few cases in which red (W26) was used to check for cone intrusion. Flash intensities varied from -1 to 1.7 log scot td-s. RESULTS: Dark-adapted, multifocal ERGs to blue flashes had a small, early component followed by a larger, late component. The early component showed little change in amplitude with increasing intensity. Comparisons with the full-field ERGs indicated that the early component was the focal response. The larger, late component was the response to stray light, and it can be suppressed with the addition of a surround. The focal response was from a relatively circumscribed retinal region. This is shown by comparing the multifocal rod responses from a patient with retinitis pigmentosa to her behaviorally measured rod visual field. CONCLUSIONS: By choosing conditions (namely, flashes of moderate intensity with a surround) to minimize the effects of stray light, multifocal rod ERGs can be recorded with sufficient localization to be clinically useful. However, the signal-to-noise ratio of these multifocal rod ERGs was poorer than for multifocal cone responses for comparable recording periods because of the need for blank frames and the slower recovery of the rods to successive presentations
— id: 57168, year: 1998, vol: 39, page: 1152, stat: Journal Article,

Assessment of local retinal function in patients with retinitis pigmentosa using the multi-focal ERG technique
Hood, D C; Holopigian, K; Greenstein, V; Seiple, W; Li, J; Sutter, E E; Carr, R E
1998 Jan;38(1):163-179, Vision research
To assess local retinal function in patients with retinitis pigmentosa (RP), multi-focal ERGs and local thresholds (static visual fields) were obtained on eight RP patients with visual acuities of 20/25 or better. All eight patients showed multi-focal responses with normal timing within the central 5 deg. However, there were few responses with normal timing in the areas outside the central 7.5 deg, except in the case of the only patient with a 30 Hz full-field response with normal timing. Since full-field ERGs are dominated by responses from the periphery, this finding supplies a foundation for the commonly observed delays in the full-field cone ERGs of patients with RP. With respect to amplitude, only two patients showed multi-focal responses with near normal amplitudes anywhere in the field. The loss of amplitude at any point was not a good predictor of visual sensitivity in the Humphrey visual field. On the other hand, all areas with normal timing had near normal sensitivity. Timing changes appear to be an early indication of local retinal damage to the cone system. Nearly all areas with sensitivity losses greater than 0.5 log unit, and some areas with near normal sensitivity, showed significantly delayed multi-focal ERGs. Finally areas with extreme sensitivity loss show multi-focal responses with a wide range of amplitudes and implicit times across patients, suggesting different mechanisms of disease action in different patients
— id: 92135, year: 1998, vol: 38, page: 163, stat: Journal Article,

Multi-focal ERGs and visual fields in diabetic patients with macular edema
Greenstein, VC; Holopigian, K; Seiple, W; Kahanowicz, R; Katz, A
1997 MAR 15 ;38(4):3548-3548, Investigative ophthalmology & visual science. IOVS
— id: 53242, year: 1997, vol: 38, page: 3548, stat: Journal Article,

Evidence for photoreceptor changes in patients with diabetic retinopathy
Holopigian K; Greenstein VC; Seiple W; Hood DC; Carr RE
1997 Oct;38(11):2355-2365, Investigative ophthalmology & visual science. IOVS
PURPOSE: To determine whether the rod and cone photoreceptors are affected in patients with diabetic retinopathy. METHODS: Twelve patients with diabetes and varying levels of retinopathy and nine age-similar control observers participated in this study. Two-color (500 versus 650 nm) dark-adapted thresholds were measured as a function of retinal eccentricity. Full-field flash electroretinograms were obtained using brief, high-intensity flashes. Dark-adapted rod-isolated (Wratten 47B filter) and light-adapted cone-isolated (Wratten 26 filter) electroretinographic responses were measured as a function of flash intensity. The a-wave data were fitted with a model based on photopigment transduction to obtain values for the parameters of Rmax (the maximal response) and log S (sensitivity). Standard clinical 30-Hz flicker electroretinographic responses were also measured. RESULTS: Psychophysically measured dark-adapted thresholds were elevated primarily at eccentricities of 5 degrees and 10 degrees from the fovea. Analysis of rod and cone a-wave data showed that Rmax was normal in most of the patients, but log S was reduced. Analysis of b-wave and oscillatory potential parameters showed rod and cone postreceptoral abnormalities, including changes in the rod-isolated semisaturation constant (log k), cone-mediated 30-Hz flicker, and cone-isolated oscillatory potentials. The electrophysiological results were not significantly correlated with blood glucose or glycosylated hemoglobin level. CONCLUSIONS: The results provide evidence for rod and cone receptoral and postreceptoral deficits in patients with diabetic retinopathy. The photoreceptor changes are primarily in the log S (sensitivity) parameter and are attributed to transduction abnormalities
— id: 12264, year: 1997, vol: 38, page: 2355, stat: Journal Article,

Relative effects of aging and age-related macular degeneration on peripheral visual function
Holopigian K; Seiple W; Greenstein V; Kim D; Carr RE
1997 Mar;74(3):152-159, Optometry & vision science
The purpose of this study was to determine the extent of peripheral visual deficits in patients with early age-related macular degeneration (ARMD) using electrophysiological and psychophysical techniques. Dark-adaptation curves, electro-oculograms (EOGs), and electroretinograms (ERGs) were obtained from patients with early ARMD and from normally sighted control subjects. The control subjects' data were used to calculate age-dependent 95% confidence intervals for each measure of visual function. For the control subjects, performance on all our measures of visual function decreased with age. For the patients with early ARMD, the cone system absolute thresholds, EOG ratios, and cone-dominated ERG amplitudes and implicit times were within the range of normal age-related changes. Rod system absolute thresholds, cone-rod break times, and rod-dominated electroretinographic measures were abnormal in some patients. These results suggest that when the effects of aging are taken into account, some patients classified as early ARMD may not show significant changes in peripheral retinal function with standard clinical tests
— id: 56952, year: 1997, vol: 74, page: 152, stat: Journal Article,

A comparison of the components of the multifocal and full-field ERGs
Hood, D C; Seiple, W; Holopigian, K; Greenstein, V
1997 May-Jun;14(3):533-544, Visual neuroscience
The multi-input technique of Sutter and Tran (1992) yields multiple focal ERGs. The purpose here was to compare the components of this multifocal ERG to the components of the standard, full-field ERG. To record multifocal ERGs, an array of 103 hexagons was displayed on a monitor. Full-field (Ganzfeld) ERGs were elicited by flashes presented upon steady background fields. The latencies of two prominent subcomponents of the full-field ERG were altered by varying the intensity of the incremental flash or the intensity of the background field. By showing that similar manipulations of the multi-input parameters produce similar changes in latency, we were able to relate the components of the multifocal ERG to the components of the full-field ERG. The biphasic responses of the multifocal ERG appear to be generated by the same cells generating the a-wave and positive peaks of the full-field cone ERG
— id: 93714, year: 1997, vol: 14, page: 533, stat: Journal Article,

Rod multi-focal ERGs
Hood, DC; Wladis, EJ; Shady, S; Holopigian, K; Li, J; Seiple, W
1997 MAR 15 ;38(4):4121-4121, Investigative ophthalmology & visual science. IOVS
— id: 53243, year: 1997, vol: 38, page: 4121, stat: Journal Article,

Electroretinographic and psychophysical findings during early and late stages of human immunodeficiency virus infection and cytomegalovirus retinitis
Latkany PA; Holopigian K; Lorenzo-Latkany M; Seiple W
1997 Mar;104(3):445-453, Ophthalmology
PURPOSE: The authors examined electrophysiologic and psychophysical measures of retinal function in patients infected with human immunodeficiency virus (HIV) at different stages of infection, including patients with cytomegalovirus retinitis (CMVR). METHODS: All patients had complete ophthalmologic examinations. Rod-mediated psychophysical thresholds were measured using a modified two-color dark-adapted perimetry technique. Rod-dominated full field flash electroretinograms (ERGs) were obtained as a function of flash intensity, followed by cone-dominated ERGs. The 26 patients infected with HIV (26 eyes) were categorized into three groups. Six patients were infected with HIV but had not progressed to acquired immunodeficiency syndrome (AIDS), and 14 had AIDS. Six patients had CMVR with less than 10% of the retina involved. The data were compared with results from age-similar control subjects. RESULTS: Psychophysical thresholds as a function of retinal eccentricity were elevated for each of the three stages of HIV infection. The group of patients with CMVR had the greatest amount of threshold elevation and threshold elevation increased with retinal eccentricity. In addition, all three patient groups had abnormal electroretinographic findings. Patients with CMVR were affected more severely on all measures than were the other HIV-infected groups. CONCLUSIONS: Results reveal that a diffuse functional retinal pathology exists in eyes with the funduscopic appearance of localized peripheral CMVR. Additionally, patients infected with HIV, including those without cotton wool spots, may have abnormal retinal function
— id: 12368, year: 1997, vol: 104, page: 445, stat: Journal Article,

Rod phototransduction in transgenic mice expressing a mutant opsin gene
Goto, Y; Peachey, N S; Ziroli, N E; Seiple, W H; Gryczan, C; Pepperberg, D R; Naash, M I
1996 Mar;13(3):577-585, Journal of the Optical Society of America. A, Optics, image science, & vision
Rod-mediated electroretinograms (ERG's) were recorded from transgenic mice expressing a mouse opsin gene with three point mutations (V20G, P23H, and P27L; termed VPP mice) and from normal littermates. The leading edge of the alpha wave was analyzed in relation to a computational model of rod phototransduction [J. Physiol. 499, 719 (1992)], in which values for the maximum response (RmP3), transduction gain (S), and transduction delay (td) are derived from alpha-wave data. VPP mice exhibited an age-related decrease in RmP3. This decrease was consistent with reductions in the number of rod photoreceptors and in the length of rod outer segments observed in previous histological studies of the VPP retina. Values of S determined for the VPP mice were within the normal range, consistent with a normal amplification of the visual signal in VPP rods. At high stimulus intensities, both normal and VPP mice exhibited a decrease in S, which may reflect depletion of a phototransduction substrate at these stimulus levels. We examined the recovery of the alpha wave after a bright conditioning flash by measuring the rod alpha-wave response to a probe flash presented at varying times after the conditioning stimulus. In both normal and VPP mice a fourfold (0.6-log-unit) increase in conditioning stimulus intensity increased both T50%, the period required for half-maximal recovery, and tau, the exponential time constant describing recovery. However, the increases in T50% and tau were significantly greater in VPP mice, indicating an abnormally slow recovery of the flash response in VPP rods
— id: 120544, year: 1996, vol: 13, page: 577, stat: Journal Article,

Rates of change differ among measures of visual function in patients with retinitis pigmentosa
Holopigian K; Greenstein V; Seiple W; Carr RE
1996 Mar;103(3):398-405, Ophthalmology
PURPOSE: To assess changes in measures of visual function in patients with retinitis pigmentosa (RP) over time. METHODS: Patients with RP and visual acuity of 20/40 or better and central visual fields of 10 degrees or larger were enrolled in a 9-year prospective study. The following measures of visual function were obtained annually over the follow-up period: visual acuity, Goldmann visual fields (V4e target), focal electroretinograms, and hue discrimination. RESULTS: Over the follow-up period, the averaged group data showed changes in all measures of visual function. The smallest amount of change occurred for visual acuity and hue discrimination, and the greatest amount of change occurred for visual field area. Examination of individual patient data over the follow-up period indicated that the rates of change varied among patients and that losses in function for one measure did not correlate well with losses on other measures. CONCLUSIONS: These results stress that although visual function deteriorated over time for this group of patients with RP, there were differences among our measures of visual function. Measures that primarily assess central retinal function change relatively slowly compared with measures that assess more peripheral retinal function
— id: 7005, year: 1996, vol: 103, page: 398, stat: Journal Article,

Assessment of receptoral and post-receptoral changes in primary open-angle glaucoma
Holopigian, K; Pollack, A; Greenstein, VC; Seiple, W; Hood, DC; Ritch, R
1996 FEB 15 ;37(3):2343-2343, Investigative ophthalmology & visual science. IOVS
— id: 53023, year: 1996, vol: 37, page: 2343, stat: Journal Article,

Do the delays in the cone ERG from patients with RP indicate global retinal damage?
Hood, DC; Holopigian, K; Greenstein, VC; Seiple, W; Carr, RE; Sutter, EE
1996 FEB 15 ;37(3):1558-1558, Investigative ophthalmology & visual science. IOVS
— id: 53022, year: 1996, vol: 37, page: 1558, stat: Journal Article,

Outer-retina locus of increased flicker sensitivity of the peripheral retina
Seiple W; Holopigian K
1996 Mar;13(3):658-666, Journal of the Optical Society of America. Pt. A. Optics & image science
We tested alternative hypotheses concerning the locus of enhanced flicker sensitivity observed in response to stimuli presented to the peripheral retina. The first hypothesis attributes increased temporal frequency sensitivity to ganglion cell and higher-order neural processing, whereas the second hypothesis states that the locus of these temporal effects is at the cone photoreceptors. To test these alternative hypotheses we measured retinal electrophysiological and psychophysical temporal modulation thresholds. We found that sensitivity for temporal frequencies < 30 Hz did not vary as a function of retinal location for either the focal electroretinogram (ERG) or the psychophysical measure. However, for both measures, sensitivity for temporal frequencies > or = 30 Hz was greater in the peripheral retina than in the central retina. In addition, critical flicker frequency for the central retina was linear as a function of retinal illuminance for both the psychophysical and the electrophysiological measures. For the peripheral retina the slopes of critical flicker frequency versus log illuminance functions were steeper than the central slopes for both threshold measures. Eccentrically measured focal ERG and psychophysical critical flicker frequency values showed a relative saturation, deviating from the linear slope above 3.5 log Td. The findings of similar focal ERG and psychophysical temporal sensitivity changes with eccentricity support an outer retinal origin of this phenomenon
— id: 7046, year: 1996, vol: 13, page: 658, stat: Journal Article,

Age-related functional field losses are not eccentricity dependent
Seiple W; Szlyk JP; Yang S; Holopigian K
1996 Jun;36(12):1859-1866, Vision research
Previous studies have found an increase in peripheral target localization errors in normally sighted older adults. These results have been interpreted as indicative of a constriction of the 'useful field of view'. In the present study, we parametrically manipulated masking, distractors and stimulus luminance and examined the relationships between peripheral target localization and age. We found that backward masking and/or flashed distractors increased error rates. This decrement in performance was larger for more peripherally located targets and largest for the older subjects at all stimulus locations. Stimulus luminance (either 2 or 78 cd/m2) had no effect on peripheral localization performance at any age. We also demonstrated that all subjects, regardless of age, had higher localization error rates to more peripherally located targets. In older subjects, error rates increased equally at all eccentricities; that is, there was an eccentricity independent increase in the number of target localization errors as a function of age. This finding does not support the interpretation of a selective constriction of the functional visual field in older subjects
— id: 56990, year: 1996, vol: 36, page: 1859, stat: Journal Article,

ROD AND CONE PHOTORECEPTOR ANALYSIS IN PATIENTS WITH DIABETIC-RETINOPATHY
HOLOPIGIAN, K; KELLY, R; GREENSTEIN, VC; SEIPLE, W; HOOD, DC
1995 MAR 15 ;36(4):S480-S480, Investigative ophthalmology & visual science. IOVS
— id: 87337, year: 1995, vol: 36, page: S480, stat: Journal Article,

The effects of random element loss on letter identification: implications for visual acuity loss in patients with retinitis pigmentosa
Seiple W; Holopigian K; Szlyk JP; Greenstein VC
1995 Jul;35(14):2057-2066, Vision research
The hypothesis that reductions in Snellen acuities in patients with retinitis pigmentosa are due solely to losses of photoreceptors was tested by measuring the effects of random losses of sampling elements on letter identification. Sampling element losses were mimicked by setting the luminance of randomly selected pixels equal to the luminance of the surround. The amount of pixel blanking ranged from 0 to 90%. Letters varying in retinal subtense from 5 to 17 min arc were presented for 500 msec. Although letter identification accuracy decreased with increasing pixel blanking for all letter sizes, performance remained relatively high even when a majority of the pixels was blanked. The data suggest that unless the loss of cone photoreceptors in greater than 80%, loss of sampling elements alone can not account for letter acuities poorer than 20/40. In addition to loss of cone photoreceptors in patients with RP, there are histological reports of photoreceptor abnormalities and psychophysical studies of visual sensory deficits. It is conceivable that these alone, or in combination with losses of photoreceptors, could account for decreased visual acuity. In a series of experiments, stimulus parameters were manipulated in order to mimic the effects of some of these abnormalities and deficits and the effects on letter identification were examined. The results of these experiments demonstrated that sampling element loss interacts with sensory factors (e.g. luminance and contrast sensitivity) and perceptual factors (e.g. set size and letter orientation) to reduce letter identification accuracy. The implication of these results is that decreases in letter acuity observed in patients with retinitis pigmentosa cannot be attributed solely to a random loss of sampling elements in the underlying retina, but may be due to the combination of photoreceptor degeneration and other sensory and perceptual factors
— id: 56847, year: 1995, vol: 35, page: 2057, stat: Journal Article,

Comparison of visual evoked potential and psychophysical contrast sensitivity
Seiple W; Kupersmith MJ; Holopigian K
1995 ;80(1-4):173-180, International journal of neuroscience
We measured contrast processing as a function of spatial and temporal frequency using three measurement techniques: psychophysical thresholds, visual evoked potential (VEP) thresholds and VEP amplitudes. Measurements were made using the same stimulus parameters and on the same group of subjects. The agreement among these functions depended upon the particular spatio-temporal stimulus employed and in general, there were more differences than similarities among these measures. For example, VEP derived functions (both amplitude and threshold) peaked at 4 c/deg, whereas, the psychophysical functions peaked at 1 c/deg. VEP amplitude functions were maximum at > or = 3.5 Hz, whereas both psychophysical and VEP sensitivity were maximum at < or = 2.5 Hz. VEP thresholds were broad and low pass in shape and in contrast, the psychophysical and VEP amplitude functions were band pass. In summary, comparisons among these measures of contrast processing must be made with caution
— id: 12835, year: 1995, vol: 80, page: 173, stat: Journal Article,

RELATIVE EFFECTS OF AGE AND COMPROMISED VISION ON DRIVING PERFORMANCE
SZLYK, JP; SEIPLE, W; VIANA, M
1995 JUN ;37(2):430-436, Human factors
The aim of this study was to determine the relative effects of age and compromised vision on driving-related skills and on-road accidents. A total of 107 subjects were tested. They represented four groups that varied in age and visual status, as follows: (1) a younger, normally sighted group; (2) an older, normally sighted group; (3) a younger, visually compromised group; and (4) an older, visually compromised group. Driving performance was assessed by self-reported and state-recorded accident frequency and by an evaluation of performance on an interactive driving simulator. The older groups had poorer driving-related skills, as measured with our interactive driving simulator, than had the younger groups, but they did not have significantly higher on-road accident rates than the younger groups. The older subjects and those with compromised vision had reduced risk-taking scores, as measured with a self-report questionnaire. In addition, all older drivers had increased eye movements and had slower simulator driving speeds, which suggests that behavioral compensation is made for visuocognitive/motor deficits. Regression analyses showed that compromised vision and visual field loss predicted real-world accidents in our study population
— id: 87240, year: 1995, vol: 37, page: 430, stat: Journal Article,

SYMMETRY DISCRIMINATION IN PATIENTS WITH RETINITIS-PIGMENTOSA
SZLYK, JP; SEIPLE, W; XIE, W
1995 JUN ;35(11):1633-1640, Vision research
To investigate the relative sensory and perceptual contributions to central visual function of patients with retinitis pigmentosa (RP), we tested symmetry discrimination using block patterns with varying types of symmetric organization, Eleven control subjects with normal vision and 11 patients with RP with 20/30 visual acuity or better, viewed patterns presented for 255 msec, The patterns differed in the type of symmetric organization and the subjects were required to identify the type, The control subjects performed significantly better (89.2%) than the patients (74.5%). Four hypotheses to account for these findings were tested and the results were as follows, (1) A reduction in pattern luminance did not change symmetry discrimination performance in the control subjects, (2) Large reductions in pattern contrast did not alter symmetry discrimination in the control subjects, (3) Reductions in stimulus duration, likewise, did not produce similar error patterns in the central subjects as those observed in the patients with RP, (4) Alterations in spatial sampling density did not completely account for the patients' deficits, None of the retinally based explanations alone was sufficient to account for our findings, Additionally, we suggest that alterations of sensory input may affect the perceptual encoding of the relationship among pattern elements
— id: 87297, year: 1995, vol: 35, page: 1633, stat: Journal Article,

The effects of dopamine blockade on the human flash electroretinogram
Holopigian K; Clewner L; Seiple W; Kupersmith MJ
1994 ;86(1):1-10, Documenta ophthalmologica
Single-cell electrophysiologic studies have shown that dopamine modulates retinal activity, but its role in human retinal processing is unclear. We investigated the effects of short-term oral administration of dopaminergic receptor blocking agents on the flash electroretinogram in humans. Both chlorpromazine (25 and 50 mg) and fluphenazine (1 and 2 mg) significantly reduced electroretinogram b-wave amplitudes and also selectively reduced the amplitude of the first oscillatory potential. Implicit times were not altered. Metoclopramide (10 and 20 mg) had no effect on any electroretinographic variable. Our study indicates that dopamine receptor blocking agents with both D-1 and D-2 receptor affinities reduce the amplitude of the electroretinogram in humans
— id: 57469, year: 1994, vol: 86, page: 1, stat: Journal Article,

DECREASED RETINAL FUNCTION IN HIV AIDS PATIENTS WITH AND WITHOUT CMV RETINITIS
LATKANY, P; FROST, K; HOLOPIGIAN, K; PAK, SM; LORENZO, M; SEIPLE, W
1994 MAR 15 ;35(4):1310-1310, Investigative ophthalmology & visual science. IOVS
— id: 52541, year: 1994, vol: 35, page: 1310, stat: Journal Article,

VISUAL-LOSS CAUSED BY RETINAL CHOROIDAL LESIONS ASSOCIATED WITH CAVERNOUS SINUS REGION AV SHUNTS
PAK, S; KUPERSMITH, MJ; HOLOPIGIAN, K; SEIPLE, W
1994 MAR 15 ;35(4):1374-1374, Investigative ophthalmology & visual science. IOVS
— id: 52543, year: 1994, vol: 35, page: 1374, stat: Journal Article,

The 'OFF' response of the human electroretinogram does not contribute to the brief flash 'b-wave'
Seiple W; Holopigian K
1994 Jul-Aug;11(4):667-673, Visual neuroscience
It has been assumed that the 'ON' and 'OFF' responses of the human electroretinogram (ERG) interact to produce a single waveform when brief flashes are used. To test this assumption, we examined the separate effects of stimulus intensity, the level of retinal illuminance and stimulus duration on the ERG. Both 'ON' and 'OFF' response amplitude decreased as stimulus intensity was decreased and as the level of retinal illumination was reduced. When stimulus duration was reduced, the amplitude of the 'OFF' response decreased; however, the amplitude of the 'ON' response increased. Summing of the 'ON' and 'OFF' response waveforms could not account for the increased amplitude in response to brief stimuli or for the changes in ERG wave shape. These results indicate that there is not a significant corneally recordable 'OFF' response elicited by brief stimuli, such as those commonly used to record the flash ERG
— id: 6746, year: 1994, vol: 11, page: 667, stat: Journal Article,

THE RELATIVE EFFECTS OF AGING AND COMPROMISED VISION ON DRIVING PERFORMANCE
SZLYK, JP; SEIPLE, W
1994 MAR 15 ;35(4):1952-1952, Investigative ophthalmology & visual science. IOVS
— id: 52560, year: 1994, vol: 35, page: 1952, stat: Journal Article,

Visual evoked potentials following abrupt contrast changes
Xin D; Seiple W; Holopigian K; Kupersmith MJ
1994 Nov;34(21):2813-2821, Vision research
The timing of visual evoked potential (VEP) amplitude and phase changes following abrupt increases or decreases in contrast was examined. Gratings (1 c/deg) were presented at a low contrast for 8 sec, increased to a higher contrast for 8 sec, and then decreased to the initial lower contrast for another 8 sec. Second harmonic VEP amplitude and phase were recorded continuously and averaged in 1 sec epochs. Both amplitude and phase exhibited delays in reaching a stable level following the contrast change. For amplitude, the length of the delay was dependent on the magnitude and direction of the contrast step and on the spatial frequency of the stimulus. Time constants for the change in amplitude following step increases in contrast ranged from 0.2 sec for a 12% contrast step to 1.34 sec for a 37% contrast step. The timing of phase changes, however, was independent of the size of the contrast increases (tau = 0.7 sec). For step decreases in contrast, both amplitude and phase were relatively independent of the size of the change (tau = approx. 0.9 sec for amplitude and tau = 0.15 sec for phase). Amplitude time constants also increased with increasing spatial frequency (tau = 1.2 sec for 1 c/deg, tau = 1.6 sec for 4 c/deg and tau = 2.3 sec for 8 c/deg); phase time constants, however, did not change as a function of spatial frequency (tau = 0.7 for all spatial frequencies). These findings demonstrate that a unitary process may not always be tapped by signal averaging techniques. Additionally, swept stimulus VEP techniques may produce considerable errors in threshold estimation depending on the stimulus spatial frequency and on the slope and direction of the contrast change
— id: 56731, year: 1994, vol: 34, page: 2813, stat: Journal Article,

INCREMENT THRESHOLD CURVES - THE EFFECTS OF PERIODIC AND APERIODIC STIMULI
YANG, S; HU, HP; GREENSTEIN, VC; HOLOPIGIAN, K; SEIPLE, W
1994 MAR 15 ;35(4):1835-1835, Investigative ophthalmology & visual science. IOVS
— id: 52556, year: 1994, vol: 35, page: 1835, stat: Journal Article,

PROSPECTIVE-STUDY OF CENTRAL VISUAL FUNCTION IN RETINITIS-PIGMENTOSA
CARR, R; HOLOPIGIAN, K; GREENSTEIN, V; KY, W; HALEVY, D; SEIPLE, W
1993 MAR 15 ;34(4):1369-1369, Investigative ophthalmology & visual science. IOVS
— id: 54327, year: 1993, vol: 34, page: 1369, stat: Journal Article,

The effects of acetazolamide on visual function in retinitis pigmentosa
Greenstein VC; Holopigian K; Siderides E; Seiple W; Carr RE
1993 Jan;34(1):269-273, Investigative ophthalmology & visual science. IOVS
PURPOSE. To study the effects of acetazolamide on central and peripheral visual function in patients with retinitis pigmentosa (RP) who showed no evidence of macular edema. METHODS. Thirteen patients with retinitis pigmentosa participated in a preliminary study. Measures of central and peripheral visual function were obtained before and after an 8 wk period on acetazolamide. An additional 10 patients participated in a cross-over study. They were placed on a placebo for an 8 wk period, then on acetazolamide for a second 8 wk period. RESULTS. None of the patients in the preliminary study showed significant changes in visual acuity, color vision, foveal cone pathway sensitivities, focal electroretinogram (ERG) amplitudes, or in any ERG parameter. Three patients, however, showed significant changes in visual field area and in dark-adapted thresholds. None of the patients in the cross-over study showed significant increases in visual field area. CONCLUSIONS. Given the results and the reports of side-effects, it is difficult to justify using acetazolamide to improve retinal function in RP patients who show no evidence of cystoid macular edema
— id: 13297, year: 1993, vol: 34, page: 269, stat: Journal Article,

ELECTROPHYSIOLOGICAL EVIDENCE FOR OUTER RETINAL DEFICITS IN PRIMARY OPEN ANGLE GLAUCOMA
HOLOPIGIAN, K; SEIPLE, W; GREENSTEIN, VC
1993 MAR 15 ;34(4):1269-1269, Investigative ophthalmology & visual science. IOVS
— id: 54326, year: 1993, vol: 34, page: 1269, stat: Journal Article,

Electro-oculogram changes in patients with ocular hypertension and primary open-angle glaucoma
Mehaffey L; Holopigian K; Seiple W
1993 ;83(2):103-110, Documenta ophthalmologica
Recent evidence suggests that retinal hypoxia and ischemia affect the standing potential of the eye and the activity of the photoreceptors. To test whether chronically elevated intraocular pressure would produce similar effects, we measured electro-oculograms in two groups of patients: ocular hypertensive patients and patients with primary open-angle glaucoma. There were significant differences among the average electro-oculogram ratios of these groups compared to age-similar controls. The control observers had an average light-peak/dark-trough ratio of 2.86, the ocular hypertensive patients had an average ratio of 2.44, and the patients with primary open-angle glaucoma had an average ratio of 2.07. This indicates that long-term elevations in intraocular pressure can decrease the light peak of the electro-oculogram, even in patients with no other evidence of glaucomatous damage. This deficit may have its origins in the sensitivity of the outer retina to choroidal ischemia
— id: 57458, year: 1993, vol: 83, page: 103, stat: Journal Article,

Comparison of P100 and P300 cortical potentials in spatial frequency discrimination
Mehaffey, L 3rd; Seiple, W; Holopigian, K
1993 ;85(2):173-183, Documenta ophthalmologica
The P300 cortical evoked potential was compared to the P100 wave of the visual evoked potential by means of appearance/disappearance gratings. The spatial frequency of the novel stimulus was varied to compare the effect of task sensory difficulty on both P100 and P300 potentials. The P100 showed a steady increase in latency with the spatial frequency of the uncommon stimulus, and a degree of amplitude tuning consistent with the contrast sensitivity function. The P300 showed marked changes in both amplitude and latency dependent almost wholly on the proximity of the uncommon stimulus spatial frequency to that of the common stimulus. Motor reaction time showed elements of both the P100 and P300 response patterns. The results are consistent with a model in which, after visual information arrives at the visual cortex, processing is parallel and interdependent. In this model, the amplitude and latency of the P100 cortical evoked potential are governed solely by properties intrinsic to the stimulus, whereas the amplitude and latency of the P300 are functions of the degree of stimulus mismatch
— id: 93715, year: 1993, vol: 85, page: 173, stat: Journal Article,

Sites of cone system sensitivity loss in retinitis pigmentosa
Seiple WH; Holopigian K; Greenstein VC; Hood DC
1993 Aug;34(9):2638-2645, Investigative ophthalmology & visual science. IOVS
PURPOSE. To examine the sites of cone sensitivity loss in patients with retinitis pigmentosa by comparing focal electroretinographic and psychophysical modulation thresholds. METHODS. Both psychophysical and electrophysiologic increment threshold curves were obtained in retinitis pigmentosa patients and a group of age-matched, normally-sighted adults. RESULTS. The majority of the retinitis pigmentosa data could be accounted for by a vertical displacement of the normal curve. The retinitis pigmentosa patients showed similar patterns of cone sensitivity losses using both techniques. CONCLUSIONS. The combined electrophysiologic and psychophysical results provide support for an outer retina locus for these cone sensitivity losses. The data suggest that these deficits may be caused by a spatially independent loss of cone photoreceptors with normal adaptation properties in the remaining photoreceptors
— id: 56588, year: 1993, vol: 34, page: 2638, stat: Journal Article,

INDEPENDENCE OF SAMPLING DENSITY AND VISUAL RECOGNITION
SEIPLE, W; HOLOPIGIAN, K; SZLYK, JP
1993 MAR 15 ;34(4):777-777, Investigative ophthalmology & visual science. IOVS
— id: 54317, year: 1993, vol: 34, page: 777, stat: Journal Article,

SYMMETRY DISCRIMINATION - AN ALTERNATIVE TEST OF VISUAL FUNCTION IN PATIENTS WITH RETINITIS-PIGMENTOSA
SZLYK, JP; SEIPLE, W; XIE, W
1993 MAR 15 ;34(4):1419-1419, Investigative ophthalmology & visual science. IOVS
— id: 54328, year: 1993, vol: 34, page: 1419, stat: Journal Article,

SUPRATHRESHOLD VEP EVIDENCE OF MERIDIONAL AMBLYOPIA
XIN, D; KUPERSMITH, MJ; SEIPLE, W; HOLOPIGIAN, K
1993 MAR 15 ;34(4):864-864, Investigative ophthalmology & visual science. IOVS
— id: 54318, year: 1993, vol: 34, page: 864, stat: Journal Article,

THE EFFECTS OF ACETAZOLAMIDE ON CENTRAL AND PERIPHERAL VISUAL FUNCTION IN RETINITIS-PIGMENTOSA
CARR, R; GREENSTEIN, V; HOLOPIGIAN, K; SEIPLE, W
1992 MAR 15 ;33(4):1072-1072, Investigative ophthalmology & visual science. IOVS
— id: 52049, year: 1992, vol: 33, page: 1072, stat: Journal Article,

A comparison of photopic and scotopic electroretinographic changes in early diabetic retinopathy
Holopigian K; Seiple W; Lorenzo M; Carr R
1992 Sep;33(10):2773-2780, Investigative ophthalmology & visual science. IOVS
Previous studies of early diabetic retinopathy have shown that oscillatory potential (OP) amplitudes are reduced in many diabetic patients. OP amplitude is believed to be a more sensitive indicator of the development of future retinopathy than b-wave amplitude of the scotopic electroretinogram (ERG). Because OPs measured to a bright white flash reflect both rod and cone system activity, it is important to compare OP amplitudes to photopic ERG measures as well as scotopic measures in early diabetic retinopathy. In this study, OPs and ERG responses were measured under photopic and scotopic conditions in a group of diabetic patients. Although OPs were reduced in amplitude in the diabetic group, several other parameters of the scotopic and photopic b-waves were impaired. The results indicate that b-wave activity may indicate retinal changes in early diabetic retinopathy in the same manner as the OPs
— id: 57456, year: 1992, vol: 33, page: 2773, stat: Journal Article,

ANALYSIS OF ROD SYSTEM ACTIVITY IN DIABETES-MELLITUS
HOLOPIGIAN, K; GREENSTEIN, V; SEIPLE, W; WEINER, M; HOOD, D
1992 MAR 15 ;33(4):1365-1365, Investigative ophthalmology & visual science. IOVS
— id: 52056, year: 1992, vol: 33, page: 1365, stat: Journal Article,

FUNCTIONAL VISUAL-FIELDS - DIFFERENTIATION OF PERCEPTUAL AND SENSORY LOSSES
JONES, LF; SZLYK, JP; SEIPLE, W; FISHMAN, GA
1992 MAR 15 ;33(4):1345-1345, Investigative ophthalmology & visual science. IOVS
— id: 52055, year: 1992, vol: 33, page: 1345, stat: Journal Article,

ELECTROPHYSIOLOGICAL AND PSYCHOPHYSICAL ASSESSMENT OF AGE-RELATED MACULAR DEGENERATION
KIM, D; DUBOVY, S; HOLOPIGIAN, K; GREENSTEIN, V; SEIPLE, W; CARR, R
1992 MAR 15 ;33(4):1231-1231, Investigative ophthalmology & visual science. IOVS
— id: 52053, year: 1992, vol: 33, page: 1231, stat: Journal Article,

OPTIC ATROPHY FAILS TO ALTER THE FLASH ELECTRORETINOGRAM
KUPERSMITH MJ; GUPTA K; SEIPLE WH; HOLOPIGIAN K
1992 MAY ;7(3):247-250, Clinical vision sciences
Seven patients with longstanding monocular optic atrophy had normal flash electroretinograms when compared to the results from control observers or when compared to the results from their own unaffected eye, or the eyes of control observers. These findings are contrasted with prior investigations that report either depression or augmentation of ERG amplitudes. We found that optic nerve damage does not cause trans-synaptic changes in the retina, or loss of efferent inhibition that can be measured by electroretinography
— id: 130408, year: 1992, vol: 7, page: 247, stat: Journal Article,

Maculopathy caused by intra-arterially administered cisplatin and intravenously administered carmustine
Kupersmith MJ; Seiple WH; Holopigian K; Noble K; Hiesiger E; Warren F
1992 Apr 15;113(4):435-438, American journal of ophthalmology
Eight patients with malignant gliomas were monitored with clinical examinations to study the effects of the combination of intravenous administration of carmustine and infraophthalmic intra-arterial administration of cisplatin on retinal and optic nerve function. Three patients developed a severe macular retinal pigment abnormality in the eye ipsilateral to the intra-arterial infusion. Electrophysiologic studies disclosed no evidence of a generalized disturbance in the photoreceptors, middle retinal layers, or retinal pigment epithelium. In contrast to previous studies involving patients whose visual loss was caused by vaso-occlusive lesions in the retina and optic nerve, our study involved patients with clinically significant maculopathy, that was not vascular in origin and that developed after treatment with carmustine and cisplatin. We suggest that the deficit may result from a localized retinal pigment disturbance in the macula
— id: 13630, year: 1992, vol: 113, page: 435, stat: Journal Article,

Human VEP contrast modulation sensitivity: separation of magno- and parvocellular components
Nelson JI; Seiple WH
1992 Jan-Feb;84(1):1-12, Electroencephalography & clinical neurophysiology
Human cortical visual evoked potentials (VEPs) were retrieved in real time (without averaging). The stimuli were sinusoidal gratings whose contrast was temporally modulated about some mean value. Electrophysiologically determined contrast modulation thresholds were measured at standing contrast over the range from 2.5% to 50%, defining an increment threshold function. Increment threshold functions were obtained under two different spatio-temporal stimulus conditions identified as 'sustained' (4 c/deg grating modulated at 1.5 Hz) and 'transient' (1 c/deg grating modulated at 20 Hz). Under each of these conditions, threshold responses were retrieved at both the fundamental and second harmonic of the contrast modulation frequency. Under 'sustained' conditions log increment threshold responses and the fundamental the second harmonic of the modulation frequency were similar to those at the fundamental except for a saturation effect (i.e., above a mean contrast of 25% there was little further reduction in modulation sensitivity). There was no contrast gain control under 'transient' stimulus conditions. In other words, the same absolute amount of contrast change produced threshold responses for all mean levels up to 25%. This was true at both the fundamental and second harmonic of the modulation frequency. Stimulus differences produce striking differences in the electrophysiologically inferred increment threshold function for grating contrast, but fundamental and second harmonic evoked responses reflect processes with similar increment threshold behavior
— id: 13788, year: 1992, vol: 84, page: 1, stat: Journal Article,

Temporal frequency dependent adaptation at the level of the outer retina in humans
Seiple W; Holopigian K; Greenstein V; Hood DC
1992 Nov;32(11):2043-2048, Vision research
The focal electroretinogram (FERG) was used to examine temporal frequency tuning at the outer retinal level in humans by measuring temporal modulation thresholds. Changes in FERG thresholds as a function of ambient light level were compared to temporal modulation thresholds obtained psychophysically using the same stimuli. At lower temporal frequencies, both FERG and psychophysical thresholds changed sensitivity proportional to the mean illuminance level. At higher illuminance levels, both threshold measures were relatively independent of illuminance. The comparison of the FERG to the behavioral data suggest that most of the adaptation-dependent changes in temporal sensitivity in humans occur at the level of the photoreceptor complex
— id: 57457, year: 1992, vol: 32, page: 2043, stat: Journal Article,

ERG FLICKER SENSITIVITY AS A FUNCTION OF RETINAL ECCENTRICITY AND ADA
SEIPLE, W; HOLOPIGIAN, K; LORENZO, M
1992 MAR 15 ;33(4):837-837, Investigative ophthalmology & visual science. IOVS
— id: 52045, year: 1992, vol: 33, page: 837, stat: Journal Article,

PATTERNS OF REFUGE USE BY SESARMA-CINEREUM (BOSC)
SEIPLE, W; MUELLER, B
1992 JAN ;50(1):158-164, Bulletin of marine science
Patterns of refuge use and daily movement were recorded for Sesarma cinereum over two monthly observation periods. A total of 1,588 crabs were marked and released in this study and of these 576 were recaptured. Most individuals established relatively permanent shelters immediately after release and the site of each crab's shelter changed little throughout the study period. The choice of shelter location did not reflect a return to the home area since there was no correlation with the original capture area. Although a few individuals were observed to undertake long migrations along the marsh edge, most animals were consistently observed within 3 m of their refuge. The terrestrial habitat, patchy availability of shelters, and daily foraging combine to determine the nature of refuge use
— id: 51968, year: 1992, vol: 50, page: 158, stat: Journal Article,

VEP AMPLITUDE AND PHASE-CHANGES FOLLOWING DISCRETE CONTRAST STEPS
XIN, DY; KUPERSMITH, M; HOLOPIGIAN, K; SEIPLE, W
1992 MAR 15 ;33(4):833-833, Investigative ophthalmology & visual science. IOVS
— id: 52044, year: 1992, vol: 33, page: 833, stat: Journal Article,

DOPAMINE BLOCKADE HAS NO EFFECT ON THE HUMAN FLASH ERG
CLEWNER, L; HOLOPIGIAN, K; SEIPLE, W; ANGRIST, B; KUPERSMITH, M
1991 MAR 15 ;32(4):1229-1229, Investigative ophthalmology & visual science. IOVS
— id: 51686, year: 1991, vol: 32, page: 1229, stat: Journal Article,

SEPARATION OF ON AND OFF RESPONSES IN THE HUMAN ERG
HOLOPIGIAN, K; SEIPLE, W; HAN, S; CINCIRIPINI, G; CARR, R
1991 MAR 15 ;32(4):1229-1229, Investigative ophthalmology & visual science. IOVS
— id: 51685, year: 1991, vol: 32, page: 1229, stat: Journal Article,

VEP THRESHOLD AND SUPRATHRESHOLD DEFICITS IN AMBLYOPIA
Holopigian, K; Seiple, W; Kupersmith, M
1991 Apr;6(2):109-117, Clinical vision sciences
1. Strabismic and anisometropic amblyopes typically have elevated contrast thresholds. Despite these threshold losses, previous research has shown that some amblyopic observers demonstrate normal suprathreshold contrast matching. 2. One explanation for these contrasting results is a differential impairment of independent contrast mechanisms. 3. We used a swept visual evoked potential threshold technique to electrophysiologically isolate and compare absolute and suprathreshold contrast mechanisms in a group of strabismic and anisometropic amblyopes. 4. For both groups of amblyopes, the sensitivities of the absolute and the suprathreshold mechanisms were equally elevated. 5. These results indicate that, in these amblyopes, both threshold and suprathreshold mechanisms of the VEP are impaired
— id: 32189, year: 1991, vol: 6, page: 109, stat: Journal Article,

MACULOPATHY CAUSED BY CHEMOTHERAPY
KUPERSMITH, M; SEIPLE, W; HOLOPIGIAN, K; NOBLE, K; HIESIGER, E; WARREN, F
1991 MAR 15 ;32(4):690-690, Investigative ophthalmology & visual science. IOVS
— id: 51673, year: 1991, vol: 32, page: 690, stat: Journal Article,

NONLINEARITIES IN THE FOCAL ELECTRORETINOGRAM
SEIPLE, W; HOLOPIGIAN, K
1991 JAN ;6(6):413-421, Clinical vision sciences
1. At stimulation frequencies near 10 Hz, the focal electroretinogram (FERG) is non-linear, containing significant second harmonic amplitude. 2. We performed a series of experiments directed at identifying the origin of this nonlinearity. Three hypotheses were tested: (a) The frequency doubling reflects the summed contribution of responses to stimulus onset and offset. (b) The frequency doubling reflects interactions between the responses of different cone systems. (c) The frequency doubling is due to temporally separated contributions from the rod and cone systems. 3. The results of the present experiments did not support either the first (off response) or the second hypothesis (cone difference signal). The third hypothesis received the most support
— id: 52118, year: 1991, vol: 6, page: 413, stat: Journal Article,

Electrophysiological and psychophysical flicker sensitivity in patients with primary open-angle glaucoma and ocular hypertension
Holopigian, K; Seiple, W; Mayron, C; Koty, R; Lorenzo, M
1990 Sep;31(9):1863-1868, Investigative ophthalmology & visual science. IOVS
Temporal sensitivity was assessed in patients with primary open-angle glaucoma (POAG) and ocular hypertension (OHT). Three measures of flicker sensitivity were obtained: psychophysical modulation thresholds, visual-evoked potentials (VEPs), and focal electroretinograms (FERGs). We found elevated psychophysical thresholds at higher temporal frequencies (30-50 Hz) in patients with POAG, relative to thresholds for age-matched controls. The OHT patients had elevated psychophysical thresholds only at 50 Hz. On the other hand, VEP amplitudes in POAG patients were reduced at all temporal frequencies, with the magnitude of the loss increasing with temporal frequency. The OHT patients, however, showed no reductions in VEP amplitude at any temporal frequency. Finally, POAG patients' FERG amplitudes were reduced at 30-50 Hz; whereas FERG amplitudes in the OHT patients were normal at all temporal frequencies. These results indicate that OHT patients can exhibit psychophysical threshold losses at high temporal frequencies which are not observed in the suprathreshold electrophysiological amplitude measures. On the other hand, patients with POAG show both psychophysical and VEP losses across a range of temporal frequencies. In addition, the decreases in FERG amplitudes in POAG patients suggest changes in the functioning of the outer retina in this disease
— id: 93716, year: 1990, vol: 31, page: 1863, stat: Journal Article,

Losses of temporal modulation sensitivity in retinal degenerations
Seiple W; Greenstein V; Carr R
1989 Jun;73(6):440-447, British journal of ophthalmology
Sensitivity losses in patients with retinitis pigmentosa (RP) have been attributed to a decrease in photopigment density, to a reduction in the number of photoreceptors, and also to a change in temporal response properties of the receptors. The sensitivity losses in patients with macular degeneration have also been attributed to a loss of photoreceptors. To test these explanations for sensitivity loss we obtained electrophysiological and psychophysical temporal modulation transfer functions (MTFs) on normal subjects in response to varying stimulus luminances and retinal loci. These stimulus manipulations did not duplicate the changes observed in the temporal MTFs of patients. The temporal response properties of the receptors were tested electrophysiologically by manipulating stimulus presentation interval. The results provided evidence for sensitivity losses in RP patients being due to alterations in the temporal response properties of the receptors
— id: 10593, year: 1989, vol: 73, page: 440, stat: Journal Article,

An examination of VEP response phase
Seiple W; Holopigian K
1989 Dec;73(6):520-531, Electroencephalography & clinical neurophysiology
The accuracy of phase sensitive signal detection (PSD) as applied to swept visual evoked potential retrieval depends upon phase stability. If large phase shifts occur over the course of a swept run, amplitude will be lost in any one PSD channel and threshold estimation may be inaccurate. We were able to demonstrate large latency shifts in the conventional computer averaged VEP and phase shifts in the Fourier-analyzed steady-state VEP, as a function of contrast and spatial frequency. However, the phase changes observed over the portion of a sweep where there is a visually driven response are much smaller than obtained from averaged VEPs to a series of fixed stimulus values. The difference between the observed phase shifts may be caused by a delay in phase response when stimuli are swept. This hypothesis was supported by the finding that the phase of the steady-state VEP response requires from 1 to 2 sec to stabilize following a change in contrast. Sweeping contrast or spatial frequency results in a physiologically different response than when averaged VEP responses are measured to discrete changes in stimulus parameters
— id: 10425, year: 1989, vol: 73, page: 520, stat: Journal Article,

The clinical utility of visual-evoked potential acuity testing
Steele M; Seiple WH; Carr RE; Klug R
1989 Nov 15;108(5):572-577, American journal of ophthalmology
We assessed the clinical utility of objectively measured acuity using visual-evoked potentials. The technique was first standardized in normal emmetropic subjects and then applied to uncorrected myopic subjects. We found that visual-evoked potential acuity could accurately indicate Snellen acuity in emmetropia and corrected myopia; however, the two measures were highly correlated only in those uncorrected myopic subjects with visual acuities of 20/100 or better. In subjects with poorer than 20/200 uncorrected visual acuity caused by myopia, estimates of visual-evoked potential acuity could not be obtained. The correlation between these two measures of visual acuity was also lower in patients with decreased Snellen acuity attributable to retinal or ocular disease. We found that patients with unexplainable claims of decreased visual acuity could be diagnosed as having functional visual loss based on objective visual-evoked potential acuities
— id: 10428, year: 1989, vol: 108, page: 572, stat: Journal Article,

Variability of the pattern electroretinogram
Holopigian K; Snow J; Seiple W; Siegel I
1988 Sep;70(1):103-115, Documenta ophthalmologica
Conflicting results have been obtained concerning the parametric properties of the pattern electroretinogram. These discrepancies may be due to the large amount of variability inherent in recording amplitudes. We have found the variability within a single stimulus condition to be so large (ranging from 30% to 67% of the mean value) that it could mask any underlying spatial frequency tuning. Changing the stimulus conditions failed to significantly reduce the observed variability, although changing recording conditions produced some reduction. The use of a narrower rejection band, a greater number of sweeps, and placement of the reference electrode on the ipsilateral ear (as opposed to the ipsilateral temple) combined to decrease variability of the pattern electroretinogram within a single recording session; however, intersession variability remained high. Therefore one must be careful in evaluating data from this technique, and caution is advised in its clinical use
— id: 10972, year: 1988, vol: 70, page: 103, stat: Journal Article,

VEP ADAPTATION IN NORMALS AND SEIZURE DISORDERS
Kupersmith, M; Seiple, W; Nelson, J
1988 Feb;69(2):P32-P32, Electroencephalography & clinical neurophysiology
— id: 31550, year: 1988, vol: 69, page: P32, stat: Journal Article,

Changes in the focal electroretinogram with retinal eccentricity
Seiple W; Greenstein V; Holopigian K; Carr R
1988 Sep;70(1):29-36, Documenta ophthalmologica
Flicker sensitivity increases in the peripheral retina when relatively large targets are used. This enhancement of cone system-mediated temporal sensitivity persists even when corrections are made for cortical magnification factors. It has been suggested that the differences in temporal frequency response characteristics across the retina are based on differences in receptor morphology between the peripheral and central cones. We have examined a possible retinal origin of this phenomenon by obtaining psychophysical and electroretinographic data at a variety of locations on the temporal retina. Psychophysical results show an increased sensitivity for high temporal frequency stimuli (above 30 Hz) with retinal eccentricity whether or not the stimulus size was scaled. Focal electroretinograms recorded with a constant size stimulus did not show an increase in amplitude with eccentricity. However, when an equal number of receptors were stimulated by scaling the target size, focal amplitudes were larger in the periphery. The electrophysiological findings are consistent with a possible retinal origin for this flicker enhancement phenomenon
— id: 10971, year: 1988, vol: 70, page: 29, stat: Journal Article,

EVOKED-POTENTIAL ASSESSMENT OF CORTICAL ADAPTATION
SEIPLE, W; KUPERSMITH, M; NELSON, J; CARR, R
1988 MAR 15 ;27(6):1089-1093, Journal of the Optical Society of America. Pt. B. Optical physics
— id: 41846, year: 1988, vol: 27, page: 1089, stat: Journal Article,

Pattern electroretinogram threshold does not show contrast adaptation
Brigell MG; Peachey NS; Seiple WH
1987 Sep;28(9):1614-1616, Investigative ophthalmology & visual science. IOVS
Pattern electroretinogram (PERG) thresholds were examined using a swept contrast stimulus method. Stimulus contrast was either continuously changed (swept) from high to low (descending sweep), or from low to high (ascending sweep). Visual evoked potential (VEP) contrast threshold was higher when measured using descending sweeps than when using ascending sweeps. This VEP threshold difference has been attributed to cortical adaptation. Although previous work has reported changes in the PERG amplitude as a function of pre-exposure, we have found no analogous effect on the PERG threshold
— id: 65739, year: 1987, vol: 28, page: 1614, stat: Journal Article,

Contrast sensitivity of the human pattern electroretinogram
Peachey, N S; Seiple, W H
1987 Jan;28(1):151-157, Investigative ophthalmology & visual science. IOVS
Contrast thresholds for the pattern electroretinogram (PERG) were measured using lock-in amplifier retrieval of the retinal signal and a swept contrast display. Contrast sensitivity functions (CSF) developed from these PERG contrast thresholds were compared with those established psychophysically under identical stimulus conditions. Whereas the PERG CSF showed a band-pass characteristic across temporal frequency, the psychophysical CSF (and a temporal CSF developed from visual evoked potential contrast thresholds) had a low-pass pattern. Across spatial frequency, the PERG and psychophysical CSFs had similar shapes, although the PERG CSF peaked at a lower spatial frequency than the psychophysical CSF
— id: 120546, year: 1987, vol: 28, page: 151, stat: Journal Article,

Rod influence on thresholds using different detection criteria during dark adaptation
Peachey, N S; Seiple, W H; Auerbach, E; Armington, J C
1987 Mar;64(3):261-270, Acta psychologica
— id: 120545, year: 1987, vol: 64, page: 261, stat: Journal Article,

REPRODUCTIVE, GROWTH AND LIFE-HISTORY CONTRASTS BETWEEN 2 SPECIES OF GRAPSID CRABS, SESARMA-CINEREUM AND SESARMA-RETICULATUM
SEIPLE, WH; SALMON, M
1987 FEB ;94(1):1-6, Marine biology
— id: 41738, year: 1987, vol: 94, page: 1, stat: Journal Article,

Cone function in congenital nyctalopia
Siegel IM; Greenstein VC; Seiple WH; Carr RE
1987 Mar;65(3):307-318, Documenta ophthalmologica
A patient with congenital stationary night blindness (CSNB) (Schubert-Bornschein type) transmitted as an autosomal recessive trait was studied with several tests of electrical function as well as a variety of psychophysical procedures. Comparison of the patient's present findings with those obtained 23 years earlier showed that while rod thresholds have remained the same, cone sensitivity has decreased. Subjective flicker thresholds obtained following a bleach were unchanged during the course of dark adaptation. The absence of rod-cone interaction, together with an absent scotopic b-wave, implies that the defect is in the mid-retinal layers. Further, the absence of oscillatory potentials in the photopic electroretinogram (ERG) suggests that the interplexiform cell may be implicated in some manner. The focal ERG of the CSNB patient showed normal amplitude and normal phase delays, supporting the idea that the focal ERG samples primarily cone photoreceptor activity
— id: 11396, year: 1987, vol: 65, page: 307, stat: Journal Article,

HATCHING RHYTHMS OF FIDDLER-CRABS AND ASSOCIATED SPECIES AT BEAUFORT, NORTH-CAROLINA
SALMON, M; SEIPLE, WH; MORGAN, SG
1986 FEB ;6(1):24-36, Journal of crustacean biology
— id: 41619, year: 1986, vol: 6, page: 24, stat: Journal Article,

ELECTROPHYSIOLOGICAL ASSESSMENT OF APHAKIC CYSTOID MACULAR EDEMA
SALZMAN, J; SEIPLE, W; CARR, R; YANNUZZI, L
1986 NOV ;70(11):819-824, British journal of ophthalmology
— id: 41537, year: 1986, vol: 70, page: 819, stat: Journal Article,

Evaluating macular function using the focal ERG
Seiple, W H; Siegel, I M; Carr, R E; Mayron, C
1986 Jul;27(7):1123-1130, Investigative ophthalmology & visual science. IOVS
A stimulus consisting of 96 red LEDs mounted in the rear of a ganzfeld bowl was used to elicit focal electroretinograms (FERG) from the central 9 degrees of the retina in human subjects. The luminance of the stimulus was driven sinusoidally at frequencies from 10-60 Hz. The temporal responsiveness and response phase lags of normal subjects and patients with retinal disease were measured. Normal subjects produced maximum amplitude FERG responses to stimuli between 30-40 Hz. Patients with retinitis pigmentosa showed a low-pass pattern of amplitude loss, with an additional frequency independent loss in sensitivity in those with poorer visual acuity. Patients with macular degeneration showed general amplitude loss associated with a relative sparing of the mid-temporal frequencies. The response phase lags in both patient groups were not significantly different from the normals. These findings point to a loss in temporal responsiveness accompanied by a secondary loss of sensitivity in these heredoretinal degenerations
— id: 92131, year: 1986, vol: 27, page: 1123, stat: Journal Article,

Objective assessment of temporal modulation transfer functions using the focal ERG
Seiple, W H; Siegel, I M; Carr, R E; Mayron, C
1986 Jan;63(1):1-6, American journal of optometry & physiological optics
Temporal modulation transfer functions (MTF's) were recorded from the macula of nine normal subjects using focal electroretinography (FERG). An array of light emitting diodes (LED's) was used to experimentally manipulate stimulus temporal frequency, modulation depth, and mean luminance values. Two techniques were used to derive FERG modulation thresholds at several temporal frequencies: conventional averaging with extrapolation to a criterion amplitude, and a swept stimulus lock-in retrieval method. These two methods produced comparable results. The electrophysiologically derived MTF's were similar in shape to those obtained psychophysically. Six patients with retinal disease were also examined; all patients showed sensitivity losses which were most marked at the higher frequencies. Such losses tended to be greater in patients with poorer visual acuity
— id: 92130, year: 1986, vol: 63, page: 1, stat: Journal Article,

Electrophysiological confirmation of orientation-specific contrast losses in multiple sclerosis
Kupersmith MJ; Nelson JI; Seiple WH; Carr RE
1984 ;436:487-491, Annals of the New York Academy of Sciences
— id: 65715, year: 1984, vol: 436, page: 487, stat: Journal Article,

Contrast sensitivity loss in multiple sclerosis. Selectivity by eye, orientation, and spatial frequency measured with the evoked potential
Kupersmith MJ; Seiple WH; Nelson JI; Carr RE
1984 Jun;25(6):632-639, Investigative ophthalmology & visual science. IOVS
Multiple sclerosis can produce highly selective losses in visual function. Psychophysical studies have demonstrated contrast sensitivity deficits for spatial frequencies or for stimulus orientations. Using real-time lock-in retrieval of the visual evoked potential, the authors measured contrast sensitivity in 15 cases with probable or definite multiple sclerosis and acuities of 20/40 or better. Sine-wave grating contrast threshold determinations for three spatial frequencies (1, 4, and 8 cycles/deg) and four orientations (0, 45, 90, and 135 deg) revealed contrast deficits in at least one spatial frequency and orientation in every case. In most cases the visual losses were spotty or multifocal, and not the same in both eyes. Some cases with highly selective patterns of orientation or spatial frequency losses were observed and are discussed in terms of involvement of cortical functional architecture in the disease
— id: 8428, year: 1984, vol: 25, page: 632, stat: Journal Article,

RAPID VISUAL ASSESSMENT FROM THE EVOKED-POTENTIAL - AN ALTERNATIVE TO COMPUTER AVERAGING
KUPERSMITH, M; NELSON, J; SEIPLE, W; CARR, R
1984 ;58(1):P10-P10, Electroencephalography & clinical neurophysiology
— id: 40925, year: 1984, vol: 58, page: P10, stat: Journal Article,

Spatiotemporal conditions which elicit or abolish the oblique effect in man: direct measurement with swept evoked potential
Nelson JI; Kupersmith MJ; Seiple WH; Weiss PA; Carr RE
1984 ;24(6):579-586, Vision research
Reversing sine wave gratings were electronically swept in spatial frequency and contrast. The acuity limits and contrast thresholds of 4 observers were inferred from evoked potential stimulus-response functions elicited by these stimuli and retrieved with a quadrature lock-in amplifier. The evoked potential functions, linearized in the case of contrast by increasing contrast logarithmically with time, were extrapolated to the point of zero response. This point provides an electrophysiologically defined threshold value for acuity and for contrast. An oblique effect (superior sensitivity for HV-oriented gratings) could reliably be demonstrated in both acuity and contrast threshold performance. This oblique effect could readily be abolished under low spatial/high temporal frequency conditions. The findings are discussed in terms of shifting relative strengths of X and Y contributions to the steady-state evoked potential
— id: 65714, year: 1984, vol: 24, page: 579, stat: Journal Article,

A rapid evoked potential index of cortical adaptation
Nelson JI; Seiple WH; Kupersmith MJ; Carr RE
1984 Nov;59(6):454-464, Electroencephalography & clinical neurophysiology
Contrast thresholds and acuity limits were measured in 4 observers with the swept visual evoked potential (VEP) technique. In this technique, grating contrast or grating spatial frequency is electronically varied while the subject's evoked response is retrieved in real time (without averaging). Contrast or spatial frequency variation make the stimulus vary in intensity; zero VEP response amplitude indicates the threshold intensity. Large shifts occur in the indicated threshold when stimulus sweep direction is reversed. Thresholds are always relatively elevated when the run begins with the strongest stimulus value. These shifts do not have a technical origin in the delay of the instrument (Nelson et al. 1984b). Here, it is shown that the shifts are due to orientation and spatial frequency selective adaptation, probably of cortical origin. Measureable adaptation is produced by momentary exposure to contrasts as low as 1.25%; nearly maximum adaptation (0.6 log units) is reached with 20% contrast. These findings support the concept of a contrast gain control mechanism in visual cortex, and pose practical problems for visual assessment with the evoked potential
— id: 65709, year: 1984, vol: 59, page: 454, stat: Journal Article,

Lock-in techniques for the swept stimulus evoked potential
Nelson JI; Seiple WH; Kupersmith MJ; Carr RE
1984 Oct;1(4):409-436, Journal of clinical neurophysiology
We discuss the use of synchronous-demodulation (lock-in) techniques for evoked potential retrieval. Application to electronically swept visual displays is emphasized. These techniques permit a visual threshold to be specified in 20 s, but their application to visual assessment requires careful consideration of several problems, notably alleged delay in the instrumentation, specification of the baseline response level, and the nature of EEG interference. In addition, since stimulus waveform information is lost in all lock-in methods, questions concerning what activity is contributing to the measured response must be answered. A technique addressing these issues and combining phase-sensitive detection and vector computation is presented
— id: 65710, year: 1984, vol: 1, page: 409, stat: Journal Article,

The assessment of evoked potential contrast thresholds using real-time retrieval
Seiple WH; Kupersmith MJ; Nelson JI; Carr RE
1984 Jun;25(6):627-631, Investigative ophthalmology & visual science. IOVS
Electrophysiologic contrast sensitivity functions (CSF) have been estimated using lock-in amplifier signal retrieval of the visually evoked response (VER). These CSFs were compared with CSFs obtained psychophysically using the same stimulus conditions. The two measures of contrast sensitivity behave similarly in response to variations of temporal and spatial frequency. The major advantage of using real-time retrieval is speed. Threshold for a single spatiotemporal condition can be estimated in as little as 20 sec, making the application of electrophysiologic contrast sensitivity testing feasible for clinical populations
— id: 65712, year: 1984, vol: 25, page: 627, stat: Journal Article,

The 20/20 eye in multiple sclerosis
Kupersmith MJ; Nelson JI; Seiple WH; Carr RE; Weiss PA
1983 Aug;33(8):1015-1020, Neurology
Using clinical and electrophysiologic measures, we evaluated the visual pathway of patients who had multiple sclerosis, 20/20 Snellen acuity, and no history of optic neuritis. Delayed latencies were found in the transient visual evoked potentials (VEPs) of 38% of the patients, and interocular latency differences were abnormal in 67%. Contrast VEPs were abnormal in 46%. Psychophysical determinations of contrast sensitivity were abnormal in 78%. Only 17% of the patients had dyschromatopsia, 36% had afferent pupillary abnormalities, and 59% had optic nerve pallor or nerve fiber layer loss. Psychophysical contrast evaluations and VEP studies were superior to other clinical evaluations in demonstrating visual dysfunction in these patients
— id: 65716, year: 1983, vol: 33, page: 1015, stat: Journal Article,

The pattern electroretinogram in optic nerve disease
Seiple W; Price MJ; Kupersmith M; Siegel IM; Carr RE
1983 Sep;90(9):1127-1132, Ophthalmology
Pattern evoked electroretinograms (PERG), diffuse flash electroretinograms (ERG) and visual evoked potentials were studied in patients with unilateral optic nerve disease. Patients with Snellen acuities of less than 6/30 did not have recordable PERGs in their affected eye, whereas their diffuse flash ERGs were normal. The VEPs were correspondingly reduced or absent when recorded from the poorer seeing eyes. A second group of patients with Snellen acuity between 6/6 and 6/30 in the involved eye showed reductions in the mean PERG amplitude of the affected as compared with the normal eyes. All affected eyes showed an abnormal contrast threshold measured with the PERG amplitude. Such results underscore the diagnostic value of the PERG in detecting even mildly affected cases of optic nerve disease
— id: 65738, year: 1983, vol: 90, page: 1127, stat: Journal Article,

Recording the pattern electroretinogram: a cautionary note
Seiple, W H; Siegel, I M
1983 Jun;24(6):796-798, Investigative ophthalmology & visual science. IOVS
It is possible to record a pattern electroretinogram (PERG) of near normal amplitude in a situation when the eye containing the active electrode is occluded. Because PERG recording requires high amplification and sensitive signal retrieval techniques, the electrode in the occluded eye records a distant potential from the unoccluded eye. Referencing the active electrode to an ipsilateral ear diminishes, but does not eliminate the referred PERG potential. Such unlooked for interaction may provide misleading data in situations where binocular viewing is used because of poor vision in one eye; therefore, occlusion of the eye not being tested should be undertaken whenever possible
— id: 120547, year: 1983, vol: 24, page: 796, stat: Journal Article,

Binocular summation and suppression: visually evoked cortical responses to dichoptically presented patterns of different spatial frequencies
Harter, M R; Seiple, W H; Musso, M
1974 Nov;14(11):1169-1180, Vision research
— id: 120548, year: 1974, vol: 14, page: 1169, stat: Journal Article,

Binocular summation of visually evoked responses to pattern stimuli in humans
Harter, M R; Seiple, W H; Salmon, L
1973 Aug;13(8):1433-1446, Vision research
— id: 120549, year: 1973, vol: 13, page: 1433, stat: Journal Article,

Evoked cortical responses to dichoptically presented patterned light flashes: interocular interaction
Harter, M R; Seiple, W H; Salmon, L E
1972 ;2(1):27-33, T.-I.-T. journal of life sciences
— id: 120550, year: 1972, vol: 2, page: 27, stat: Journal Article,