Electrophysiological and Psychophysical Studies in Congenital Retinoschisis of X-Linked Recessive Inheritance

Summary

Twenty-eight eyes of 14 males affected with congenital retinoschisis were studied. The amplitude ratio of b-over a-wave (b/a ratio) of the ERG was lower than normal in all cases including those in which the clinically visible abnormality in the fundus was limited to the macula. This characteristic pattern of the ERG could even be recognized in an advanced stage when the responses became extremely small. VER obtained by focal stimulation of the macula showed delayed peak times in all cases suggesting abnormal macular function. The light rise of the EOG was normal in all cases except one of advanced stage. Kinetic perimetry showed depression in the center and in the upper fields corresponding to the locations of the fundus abnormalities visible ophthalmoscopically. Flicker perimetry showed diffuse impairment of the cone function in the entire field. Dark adaptation curves showed in most patients elevation of the tresholds of both cones and rods. In advanced stages, the rod portion of the dark adaptation curve was entirely missing, indicating complete night blindness. The results of these studies demonstrate that there is much more profound and widespread functional abnormality in congenital retinoschisis than one would suspect from the fundus appearance. The macula as well as the area outside the macula is involved. Pathology in this disease probably starts in the inner and middle layers of the retina, and initiates later the degeneration of the receptors.

Congenital retinoschisis should be noted as a disease leading to complete night blindness. In late stages, the fundus appearance, psychophysical and electrophysiological findings may resemble those found in retinitis pigmentosa.