Electroretinographic findings in the mucopolysaccharidoses

The degree of retinal involvement of 20 patients (ages 3-21) with mucopolysaccharidosis (MPS) types I, II, and III was assessed using electroretinography (ERG) under standardized conditions. ERG evidence of retinal dysfunction ranged from none to severe in MPS I and II, and from moderate to severe in MPS III. The ERG abnormalities were common to all three types of MPS, and showed the pattern seen in rod-cone degenerations, where the rod-mediated responses are more severely affected than the cone-mediated responses. The ophthalmoscopic signs were less striking than the electrophysiologic findings, and were usually restricted to mild changes of the retinal pigment epithelium.