Rod and Cone Mediated Function in Retinal Disease

National Eye Institute

Investigators

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Abstract

Specific Aim 1: To establish the normal ranges of dark-adapted retinal sensitivities for the Medmont, and for RF hyperacuity function on the Display++ monitor in healthy volunteers. Dark-adapted retinal sensitivity has been measured with the Medmont from 44 healthy volunteers aged between 16 and 67 years. To be examine rod photoreceptor function, we developed a scotopic version of radial frequency (RF) hyperacuity test using the Display++. Such a scotopic shape discrimination task has not previously been described. We have measured scotopic shape discrimination from 39 healthy volunteers aged between16 and 80 years (some participants also completed retinal sensitivity and dark adaptation testing). Specific Aim 2: To establish the normal ranges for the kinetics of dark adaptation for the Medmont DAC blue and red stimuli in healthy volunteers. Dark adaptation has been measured with the Medmont from 32 healthy volunteers aged between 16 and 53 years (participants were the same recorded for retinal sensitivity). Specific Aim 3: To quantify local changes in rod and cone photoreceptor function across the retina in participants with retinal disease. Delayed dark adaptation (DA) is an early phenotypic marker in late onset retinal degeneration (L-ORD) and may precede symptoms and retinal changes. We used the Medmont to measure rod-mediated function in seven members of a family with L-ORD. Rod function was most severely affected in the temporal retina where structural changes are first observed in this disease. Notably, the spatial variation in loss of rod-mediated function varies between family members and local loss of rod function across the retina precedes structural change. We have followed two patients of one family over a period of three years to document disease progression. We have also documented for the first time in L-ORD patients the existence of a rod-plateau following different levels of rod-bleaching. We have shown spatial variation in rod function in AMD patients with and without reticular pseudodrusen (RPD) using both the Medmont and radial frequency hyperacuity test. AMD patients with RPD are on particular interest because of their dramatically delayed dark adaptation which is also observed in patients with L-ORD and Sorsbys . No further progress due to shutting of NIH clinics during pandemic