Concentric visual field restriction under vigabatrin therapy: extent depends on the duration of drug intake

Vigabatrin (VGB) is a novel antiepileptic drug which inhibits GABA-transami nase (GABA-T) and thus increases the level of GABA in the CNS and in its ne urons. In the last few years, evidence has been presented that VGB intake m ay be associated with concentric visual field restrictions. The aim of this study was to estimate the prevalence of visual field constrictions and to determine if, and to what extent, they depend on the duration of VGB treatm ent. Visual fields of 15 patients who were taking VGB, and 12 matched contr ol patients who had never been exposed to VGB, were investigated using a ki netic Goldmann perimeter. One of the 12 matched control patients had a slig htly restricted visual field whereas nine of the 15 VGB patients (60%) show ed a moderate to severe concentric visual field restriction. The extent of the outer isopters (V4, I4, I3, I2) depended on the duration of VGB intake. VGB treatment was clearly associated with a high prevalence of concentric visual field restriction. Moreover, the degree of visual field restriction depended on the duration of VGB intake. Further work, including longitudina l studies, is needed to clarify whether these lesions are reversible or not . (C) 2001 BEA Trading Ltd.