Modelling the Risk of Visual Field Loss Arising from Long-Term Exposure to the Antiepileptic Drug Vigabatrin: A Cross-Sectional Approach

Background The antiepileptic drug vigabatrin has been used widely since 1989, but has only been approved for use in the US since 2009. The risk:benefit of vigabatrin is generally predicated upon an assumed frequency of associated visual field loss (VAVFL) of approximately 31 %. This estimate is based upon relatively short-term usage (up to 4–5 years) and it is essential to determine whether the frequency of VAVFL increases with longer-term usage.