Visual function loss from vigabatrin - Effect of stopping the drug

Objective: To determine if visual function loss from vigabatrin use recover s after the drug is discontinued. Background: Vigabatrin is an effective an tiepileptic drug, but it is known to cause a variety of changes in visual f unction, including reductions in the visual field, visual acuity, color vis ion, and in electroretinogram (ERG) and electrooculogram amplitudes. It is not known whether these changes are reversible. Methods: Measurements of st atic and kinetic visual fields, visual acuity, color vision, and the ERG we re recorded while patients were taking vigabatrin and again in 13 patients who had discontinued the drug because of lack of efficacy or reductions in visual field. Most of the patients had been off the drug for 3 to 6 months, although two patients had been drug-free for almost 1 year. Results: Altho ugh ERG cone implicit time improved, most of the patients did not show impr ovement in either clinical measures of visual function (i.e., visual acuity , color vision, visual fields) or in ERG amplitudes. However, several patie nts who showed minimal visual field loss while on the drug had substantial recovery of ERG amplitudes. There was no statistical association between re covery of function and either duration of treatment or cumulative dosage. T he multifocal ERG showed a diffuse loss of function that was not isolated t o the periphery. Conclusions: Although the visual deficits in patients taki ng vigabatrin tend to be mild, most patients do not show improvement after they stop taking the drug. Visual field loss resulting from vigabatrin was not reversible. Visual acuity, color vision, and ERG amplitude loss may be reversible in patients with minimal or no field loss.