Focal macular electroretinogram in X-linked congenital retinoschisis.

PURPOSE To study macular function of X-linked congenital retinoschisis (CRS) by focal macular electroretinogram (MERG). METHODS MERGs were recorded with 5 degrees, 10 degrees, and 15 degrees spots in 20 patients with CRS. Seventeen patients showed foveal schisis with little or no change in foveal fluorescein angiography (Group 1), and three patients showed advanced macular changes with nonspecific macular degeneration (Group 2). RESULTS In Group 1, a-wave amplitudes were within the normal range, but b-waves and oscillatory potentials (OPs) had mean amplitudes significantly below those for normal control subjects. The mean b- to a-wave ratios, significantly lower than in normal eyes, decreased significantly with decreasing spot size. The implicit times of a-waves, b-waves, and OPs were significantly delayed. In Group 2, MERGs were nearly nondectable. CONCLUSIONS The macular pathology of CSR exists mainly in the middle and inner retinal layers, disturbing the fovea more than the perifovea, whereas degeneration of photoreceptors progresses in more advanced stage.