Introduction and Lessons from Vigabatrin (video)

Vigabatrin was introduced as an anti-seizure medication in the United Kingdom in 1989 and was extensively used until 1997 when concerns for peripheral visual field defects emerged. When the drug was approved in the United States in 2009 it carried a black box warning for the risk of permanent visual loss and the pharmaceutical company was mandated to create a drug registry to assess for visual deficits. The vigabatrin drug registry has documented a relatively large percentage (37%) of pre-existing, baseline visual deficits involving the visual system and a paucity (2%) of potential new visual findings. The vigabatrin vision study, a prospective, longitudinal, single-arm, open-label study, confirmed that adult patients with refractory complex partial seizures had a large number (around 33%) of visual deficits at baseline, and a single patient who developed bilateral peripheral field constriction about one year after therapy. An unexpected finding during this first year of therapy with vigabatrin was an increase in retinal thickness on optical coherence tomography. The experience from; vigabatrin in the United States emphasizes the importance of baseline eye findings when considering the potential for drug toxicity involving the visual pathways.