[Electrophysiology in the differential diagnosis between sex-linked ocular albinism and central nystagmus].

PURPOSE: More than 20% of nystagmus misdiagnosed as central idiopathic nystagmus are cases of recessive sex-linked ocular albinism (AOX). We have studied a family (3 generations) diagnosed as AOX in order to evaluate the diagnostic contribution of clinical data, histological data and VEP. Our purpose was to evaluate the most convenient protocol of VEP for these cases.

METHODS

Examinations included extensive clinical and ophthalmological evaluation of 36 members from 3 generations of a family, including transillumination iris photography, retinography, biopsies of skin and a special method to record VEP.

RESULTS

The results showed that iris and macula photography are significant, but macromelanosomae found in the biopsies are not pathognomonic. In our experience, flash VEP is the conclusive test, particularly with electrodes placed 3 and 6 cm off the median line, showing an interhemispheric asymmetry.

CONCLUSIONS

We conclude that clinical examination is insufficient and biopsy may be suggestive, but ocular electrophysiology (VEP) is the key to diagnosis, although the recording method remains controversial.