VISUAL FUNCTION IN RETT-SYNDROME

The authors examined refractive error, pattern onset visual evoked pot entials, ocular posture and they performed internal and external eye e xaminations in 11 subjects with Rett syndrome (aged between four and 2 4 years) and 18 normal controls (aged between six and 20 years). Subst antial refractive errors were common in the Rett syndrome group. Spect acle correction had never previously been worn and glasses were provid ed where appropriate. No subjects had nystagmus or optic nerve pallor and only one was strabismic. All subjects had recognisable and reprodu cible pattern-onset VEPs and latencies and amplitudes did not differ s ignificantly from those of the controls. All demonstrated VEP threshol ds of at least 24'. In contrast to other populations with profound dis abilities, people with Rett syndrome have good function of the afferen t visual pathways and, in view of their substantial refractive errors, are likely to benefit from spectacle correction.