Faculty Bibliography

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

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

Purpose: To 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, seif-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. Design: A cross-sectional study and survey. Participants: Sixty-two individuals with RP (mean age, 37 years) participated in the study. Methods: We obtained data about task performance from subjects' reports about their daily performance as assessed by a 53-item questionnaire and from a specialist's rating about actual ability on a 64-item battery of tasks, including ones similar to those assessed with the questionnaire. Main Outcome Measures: Clinical 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.". Results: Self-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. Conclusions: Despite 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. Ophthalmology 2001;108:65-75 (C) 2001 by the American Academy of Ophthalmology.

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

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