Fast and slow oscillations of the electro-oculogram in Best's macular dystrophy and retinitis pigmentosa.

Fast oscillations (FOs) of the electrooculogram are fluctuations in the corneo-fundal or standing potential of the eye that are greatest in response to stimulation by dark and light periods of approximately 1.25 minutes each, in contrast to the slow oscillations (SOs) of the electrooculogram, which are greatest in response to dark and light periods of approximately 12.5 minutes each. The FOs and SOs were measured in 11 patients from four families with Best's macular dystrophy who were found to have marked loss of the SOs with prolonged light peaks but relatively preserved normal or near-normal FOs. A patient with autosomal recessive retinitis pigmentosa (RP) with a pericentral distribution of pigmentary changes also had preserved FOs of abnormal phase and markedly subnormal SO with normal light-peak time. Six patients with early RP (two sisters with autosomal recessive RP and four patients from three families with autosomal dominant RP) had greater attenuation of FOs than SOs. These results can be partially explained by consideration of the generators of these potentials and the known pathophysiology of the two diseases.