Electroretinographic findings in human oculocutaneous albinism

Electroretinograms (ERGs) were obtained under dark- and light-adapted conditions from 15 human oculocutaneous albinos and compared with the results from a group of 30 normally pigmented subjects. Amplitude and implicit time measures of the ERG recordings obtained from six autosomal recessive and three autosomal dominant tyrosinase-positive albinos fell within the normal range. The six tyrosinase-negative albinos examined also had normal ERGs at low-to-moderate flash luminances. However, at the highest flash luminances, the dark-adapted ERGs of five such subjects were at or just above the normal range in amplitude, and were shorter than normal in implicit time. The dark-adapted luminance-response functions of these subjects were positioned normally on the luminance axis; light-adapted functions were shifted slightly to the left of normal. The possibility that anterior parts of the retina responding to light passing through the anterior eyewall may contribute to the ERGs obtained from tyrosinase-negative albinos was examined by recording dark-adapted ERGs with the sclera occluded. Amplitudes were reduced compared with those obtained with the sclera unoccluded, suggesting that responses to transscleral illumination contributed to the ERG in this type of albinism.