Ocular findings and visual evoked potential response in the Prader-Willi syndrome.

It has recently been suggested that aberrant misrouting of retino-geniculate-cortical (RGC) projections, a finding previously noted only in albinism, may be an additional feature of the Prader-Willi syndrome. To determine the prevalence of ocular abnormalities in patients with the syndrome and to look for evidence of misrouted RGC projections by means of testing of the pattern-onset visual evoked potential (VEP) response, we examined 12 patients with Prader-Willi syndrome, 8 albino subjects and 5 healthy control subjects. Ocular findings in the first group included telecanthus (in five subjects), strabismus, nystagmus, foveal hypoplasia, visual field defects and cataract. However, the VEP asymmetry typically seen in albinism was not noted in any of the patients with Prader-Willi syndrome. Our findings do not support previous claims of abnormal optic nerve fibre decussation in Prader-Willi syndrome.