Dark adaptation in age-related macular degeneration: relationship to the fellow eye

Abnormalities of dark adaptation have been documented in patients with age-related macular degeneration (AMD), but the relationship with the various forms of this disorder has not been studied systematically.

Dark-adapted retinal sensitivities and kinetics of dark adaptation were studied using a Humphrey visual field analyzer adapted for these purposes in patients over 64 years of age. One eye per patient was studied. Study eyes had a normal visual acuity and macular drusen only. The fellow eye was categorized as follows: group I, pigment epithelial detachments and tears of the retinal pigment epithelium (RPE); group II, choroidal neovascularization; and group III, drusen only. The results of psychophysical tests of the study eyes (group I and II and one eye of group III patients) were compared with one another and with older patients without evidence of AMD (group IV).

Retinal sensitivity was found to be most consistently abnormal nearest the fovea. The time course of dark adaptation was prolonged beyond 45 min in 10/11 patients (91%) in group I, 6/10 patients (60%) in group II, and 6/10 (60%) in group III and 1/11 (9%) in group IV.

In a high proportion of patients with visual loss from AMD in one eye, the fellow eye shows abnormal dark adaptation. These changes appear to be most pronounced in patients with detachments of the RPE in the fellow eye.