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None of the patients complained about vision problems when asked to participate into the study. Thirteen out of the 32 (40%) epilepsy patients treated with vigabatrin monotherapy had concentrically constricted visual fields (9% severely, 3 1% mildly constricted), whereas none of the carbamazepine monotherapy patients or normal controls presented with a visual field defect (chi-square test, p=0.0001). The extents of the visual fields were significantly constricted in vigabatrin group as comp ared with the visual fields of the patients in carbamazepine group or healthy controls (analysis of variance, Scheffe F-test, significant at 99%). The use of vigabatrin seems to increase the risk of a unique and specific pattern of bilateral, mainly asymp tomatic visual field constriction. This risk should be considered when using vigabatrin. Visual field testing should also be performed before treatment and during routine follow-up for patients on vigabatrin. |
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