Visual impairment in children with epilepsy treated with vigabatrin

Vigabatrin is an anti-epileptic drug particularly useful for drug-resistant partial seizures and infantile spasms. Recently, vigabatrin-induced visual field constriction (VFC) and abnormal ocular electrophysiological studies were reported. In this study, we assessed visual fields, visual evoked pote ntials (VEPs), and electroretinography (ERG) in children treated with vigab atrin. Twenty-four visually asymptomatic children underwent a clinical opht halmological examination, perimetry when appropriate, and VEP and ERG. Thir teen patients had at least one abnormal study. VFC was seen in 11 of 17 pat ients who had perimetry; 5 of 15 patients who underwent VEP testing and 4 o f 11 who underwent ERG testing had abnormal examinations. For the most part , abnormal VEPs and ERGs were found in children who also had VFC. There was a consistent trend for longer treatment periods to correlate with VFC, abn ormal ERGs, and VEPs. In summary, over half of the children treated with vi gabatrin demonstrated VFC or abnormal ocular electrophysiological studies. Perimetry seemed to be the most sensitive modality for identifying vigabatr in toxicity, Abnormal ERGs and VEPs were primarily seen in children with VF C and may be useful in monitoring children who are not appropriate candidat es for perimetry. Although the incidence of vigabatrin-induced VFC is worri some, in the context of intractable seizures or infantile spasms, therapeut ic benefits must be weighed against risks.