William Seiple

Perceived and actual performance of daily tasks: relationship to visual function tests in individuals with retinitis pigmentosa

PURPOSEnTo investigate the functioning in daily task performance of individuals with retinitis pigmentosa (RP). Goals were (1) to quantify the relationships among clinical tests of vision, self-reports, and evaluations of actual task performance to predict difficulty in these tasks; and (2) to validate self-report questionnaire data about daily task performance with observations and measurements of actual task performance conducted by a certified low-vision specialist.nnnDESIGNnA cross-sectional study and survey.nnnPARTICIPANTSnSixty-two individuals with RP (mean age, 37 years) participated in the study.nnnMETHODSnWe obtained data about task performance from subjects reports about their daily performance as assessed by a 53-item questionnaire and from a specialists rating about actual ability on a 64-item battery of tasks, including ones similar to those assessed with the questionnaire.nnnMAIN OUTCOME MEASURESnClinical measures of vision included visual acuity, visual fields using Goldmann perimetry, letter contrast sensitivity, and cone and rod electroretinogram (ERG) function. The questionnaire and functional tasks were clustered into three categories: reading, mobility, and peripheral detection.nnnRESULTSnSelf-report was correlated significantly with actual task performance. Task performance was correlated significantly with clinical test performance. Moderate or worse difficulty in performance was observed only for visual acuity worse than 20/40; log contrast sensitivity less than 1.4; a visual field area smaller than 2000 deg(2) (area equivalent to a 50-degree diameter of visual field to the Goldmann II-4-e target); and ERG amplitudes less than 10 microvolts for 32-Hz light-adapted white flicker.nnnCONCLUSIONSnDespite the significant correlations, there remains variability in task performance that is unaccounted for in some individuals with low levels of clinical test performance. The assessment of actual task performance validated the use of self-reports in individuals with RP.

Detection using the multifocal electroretinogram of mosaic retinal dysfunction in carriers of X-linked retinitis pigmentosa

PURPOSEnTo 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).nnnDESIGNnProspective observational case series.nnnPARTICIPANTSnFive obligate carriers of XLRP (mean age, 53.2 years) were recruited into the study.nnnMETHODSnExamination 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 40 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.nnnMAIN OUTCOME MEASURESnMapping of 103 local electroretinographic response amplitudes and implicit times within the central 40 with the multifocal electroretinogram.nnnRESULTSnLocalized 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.nnnCONCLUSIONSnThe 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.

Localized retinal dysfunction in central serous chorioretinopathy as measured using the multifocal electroretinogram

PURPOSEnTo determine the extent of electrophysiologic dysfunction in patients with central serous chorioretinopathy (CSC).nnnDESIGNnProspective observational case series.nnnPARTICIPANTSnSix patients with unilateral CSC (mean age, 40 years) were recruited into the study.nnnMETHODSnSix 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.nnnMAIN OUTCOME MEASURESnLocal electroretinographic response amplitudes and implicit times within the central 40 degrees with the mfERG.nnnRESULTSnAll the clinically uninvolved eyes showed mfERG amplitudes and implicit times within the normal range throughout the central 40 degrees 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.nnnCONCLUSIONSnWe 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.

Detection of Mosaic Retinal Dysfunction in Choroideremia Carriers Electroretinographic and Psychophysical Testing

PURPOSEnTo 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.nnnDESIGNnProspective observational case series.nnnPARTICIPANTSnSeven obligate choroideremia carriers (age range, 18-72) with visual acuity (VA) of 20/25 or better were recruited into the study.nnnMETHODSnThe 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.nnnMAIN OUTCOME MEASURESnMapping of local 103 electroretinographic response amplitudes and implicit times.nnnRESULTSnOnly 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.nnnCONCLUSIONSnWe 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.

Contrast Sensitivity Testing

The detection of small luminance differences between objects and their backgrounds is an important tool for navigating in the visual environment. Many visual system disorders cause patients to complain that their vision is cloudy or blurred, or that the borders of objects are blurred, even though they retain 20/20 Snellen acuity. These patients may suffer from losses in contrast sensitivity that cannot be detected using standard clinical testing. A more appropriate measure for these patients is their ability to detect small changes in luminance within a pattern. One widely used experimental measure of this ability is the contrast sensitivity function.

Multifocal ERG findings in carriers of X-linked retinoschisis

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, 46.2xa0years) 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° 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° 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.