EOG Changes in Dominantly Inherited Drusen (Malattia Leventinese)

Abstract

Dominant drusen typically lead to decrease in visual acuity at age 40–60 years and to low-normal or reduced cone and rod b-waves in the ERG. To assess electrophysiologically changes in the pigment epithelium we used the extended EOG ramp test (Rohde et al., 1981), which provides stimulation for the fast oscillation during dark adaptation of 30 min prior to a light step of 4 log units. From 14 control subjects we obtained the following data: Control EOGs(n = 28 eyes) mean SD Light peak (% of basic level) 198 15 Latency of light peak (min) 9.4 1.0 Fast oscillation(µV) 143 57.9 Fast oscillation, period (min) 2.5 0.2 14 patients (28 eyes tested), all members of affected families, exhibited drusen at the posterior pole, with or without visual loss. The fast oscillation of their EOGs revealed normal amplitudes (157 ±28 µV) and period length of 2.4 ± 0.2 min. The light peak revealed a mean of 208; i.e., 26% above the dark adapted basic level, with 2 eyes presenting ratios of less than 2 SD below mean control. The latency of the light peak-maximum was increased (10.5 ± 1.7 min), with 6 eyes presenting a delay of more than 2 SD from mean control. The data provide electrophysiologic evidence for pathology in the retinal pigment epithelium as reflected in the changes in the ratio and the frequent delay of the EOG light peak.