Longitudinal Assessment of Rod Function in Intermediate Age-Related Macular Degeneration With and Without Reticular Pseudodrusen.

Purpose: To evaluate rod function longitudinally in intermediate age-related macular degeneration subjects with reticular pseudodrusen (RPD) and without RPD (AMD). Methods: Retinal sensitivities (505 and 625 nm) during dark adaptation, at 14 locations within the central 12° macula were obtained after photobleaching at baseline and 12-month visits. Pointwise sensitivity differences between both stimuli were used to assess static rod function, while rod intercept time (RIT) and rod recovery rate (RRR) were used to evaluate dynamic function. Changes in function over time were compared between groups. Results: A total of 23 controls, 12 AMD, and 13 RPD cases were followed-up. At baseline, the RPD group had significantly worst static and dynamic rod function compared to AMD and control groups. Static function in AMD was similar to controls. Static and dynamic function across the central 12° was consistent in controls; however, it was most impaired at 4° compared to 12° eccentricity in disease groups. Over 12 months, no AMD cases progressed clinically and static function in AMD improved (P ≤ 0.04), but remained unchanged in control and RPD groups (P ≥ 0.17). The RRR for control and RPD groups remained stable, while the AMD group deteriorated, but only at 12° (P = 0.02). The RIT was stable in AMD (P = 0.75) and RPD (P = 0.71) groups but improved in the control group (P = 0.002). Conclusions: A decrease in RRR was detected over 12 months at 12° eccentricity in the AMD group. Evaluating changes in rod function requires testing at multiple locations including the peripheral macula.

Assessment of Retinotopic Rod Photoreceptor Function Using a Dark-Adapted Chromatic Perimeter in Intermediate Age-Related Macular Degeneration.

PURPOSE: We determine the feasibility of using a dark-adapted chromatic (DAC) perimeter to obtain dark-adapted static and dynamic rod function at multiple retinal locations, and compare these functional parameters between subjects with intermediate age-related macular degeneration (AMD) and normal controls. METHODS: Perimetric dark-adapted retinal sensitivities for the 505 and 620 nm stimuli across 7 retinal locations within the central 12° were repeatedly measured after exposing to a single photobleach in 22 intermediate AMD subjects and 8 controls. The sensitivities for each stimulus at 20 minutes after bleach and the sensitivity difference between the stimuli were used to determine static rod function. Sensitivities for the 505 nm stimulus at various times within the initial 20 minutes after bleach were used to estimate the rod criterion time to determine rod function dynamics. The static and dynamic rod functional parameters were compared between AMD and control eyes. RESULTS: Compared to the control eyes, AMD eyes had a reduction in retinal sensitivities for the 505 nm (P < 0.001) and 620 nm (P < 0.001) stimuli, a reduction in sensitivity difference (P < 0.001), and an increased in rod criterion time (P < 0.001). Region within the central 6° appeared to be the most defective and AMD eyes with reticular pseudodrusen (RPD) seemed to have worse function than eyes without RPD. CONCLUSIONS: It is feasible to use a DAC perimeter to study dark-adapted static and dynamic rod-mediated function at multiple retinal loci. Static and dynamic rod function were abnormal in intermediate AMD and more so in eyes with RPD, particularly within the central 6° retina.