Electroretinographical study of the hypoplasia of the optic nerve.

Out of 22 sporadic cases of hypoplasia of the optic nerve, 16 were bilateral and 6 unilateral. The sex distribution was equal in the bilateral cases, while all our unilateral cases were females. Visual impariment was severe in all our cases. There was total blindness or only light perception. The pupillary reflexes were absent or very slow. Only one case had a rather good visual acuity (1/10) with a constricted visual field. In addition to the typical aspect of hypoplasia of the optic disc, some cases showed an obvious or suspected retinal degereration, such as a marked choroidal pattern with pigmentary dystrophy of the posterior pole. The ERG was normal in most cases, and showed no modification with increasing age. No supranormal recordings were obtained. Out of 36 eyes, 12 had a subnormal response. Seven showed an involvement only of the scotopic response, one only of the photopic response and four of both responses. The reduction of the ERG amplitude was rather mild in most cases. The ERG was never extinguished. The temporal characteristics were normal in all our cases with two exceptions.