Retinal function abnormalities in patients treated with vigabatrin.

OBJECTIVE To evaluate central and peripheral retinal function in patients treated with vigabatrin, an antiepileptic drug associated with peripheral visual field constriction (VFC). METHODS Six patients with epilepsy treated with vigabatrin as add-on therapy for at least 3 years were included in this observational case series. All patients underwent a clinical ophthalmologic examination, color vision testing, standard perimetry, and full-field and focal foveal cone electroretinography. Four patients, 3 of whom had VFC, completed specialized computerized static light- and dark-adapted perimetry. RESULTS In 9 of 11 eyes tested, foveal cone electroretinographic amplitudes were at or below the lower limit of normal. Dark-adapted perimetry demonstrated abnormal rod-derived visual fields in the 3 patients with vigabatrin-attributed VFC, whereas rod-derived thresholds were within normal limits throughout the visual field in the patient who did not have VFC. CONCLUSIONS Our results suggest that vigabatrin not only impairs peripheral cone-derived function as manifested by VFC but also affects foveal cone electroretinographic amplitudes and rod-derived visual fields. The clinical dilemma regarding the use of vigabatrin therapy is further complicated since central as well as peripheral visual function seems to be adversely affected.