Abstract

Patients with retinitis pigmentosa (RP) not infrequently exhibit reductions in foveal visual acuity in addition to night blindness and peripheral visual field restrictions. Measurement of visual acuity in RP subjects has typically been made with an extended duration of target presentation. Since there is evidence of abnormal temporal processing in some RP subjects (e.g., Tyler et al., 1984; Dagnelie and Massof, 1990), it is possible that such long-duration viewing of acuity targets underestimates the degree of acuity loss under conditions of briefer target duration. To address this issue, we have examined the temporal properties of foveal vision in RP subjects using Sloan letter identification. First, we measured log MAR (minimum angle of resolution) as a function of stimulus duration to determine whether RP subjects demonstrate a greater degree of acuity loss at short durations. Second, we measured contrast thresholds as a function of stimulus duration at a fixed letter size to determine whether temporal summation for letter identification is abnormal.

© 1991 Optical Society of America