Full-field ERG and visual fields in patients 5 years after discontinuing vigabatrin therapy.

Purpose In numerous studies vigabatrin medication has been associated with visual field constriction and alterations in the full-field electroretinogram (ff-ERG), but it is not clear whether these changes are reversible or not. The purpose of this study was to examine patients with visual field loss and reduced ff-ERG several years after discontinuing vigabatrin therapy, in order to investigate reversibility. Methods Eight patients with visual field constriction and reduced cone responses measured by 30 Hz flicker ERG were examined with Goldmann perimetry and ff-ERG 4-6 years after discontinuing medication. The results were compared with investigations conducted during medication, 4-6 years previously. Statistical analysis was also used to compare the ff-ERG results of the patients, during treatment and at follow-up, with a group of 70 healthy subjects. Results Visual field constriction remained 4-6 years after discontinuing vigabatrin therapy. The amplitude of the 30 Hz flicker response also remained reduced on follow-up both compared with the results during treatment and with the control group. Moreover, the amplitude of the isolated rod response and the combined rod-cone response were decreased in the patients compared with the control group, during vigabatrin treatment as well as on follow-up. On follow-up, oscillatory potentials (OPs) also were registered, showing reduced amplitudes in patients compared with controls. The within subject comparison showed no significant changes. Conclusion Vigabatrin attributed visual field constriction and reduced ff-ERG responses remain several years after discontinuing vigabatrin therapy, indicating drug-induced permanent retinal damage.