[Visual field changes secondary to vigabatrin treatment]. / Alteraciones de los campos visuales secundarias al tratamiento con vigabatrina.

INTRODUCTION: Vigabatrin is an effective antiepileptic drug for treatment of partial crises with or without generalization. It acts by increasing GABA levels by irreversible inhibition of the enzyme GABA-transaminase. In recent years there have been several reports published on the appearance of alterations of the visual fields of patients treated with this drug. OBJECTIVE: To study the prevalence and characteristics of the visual field changes associated with vigabatrin treatment in an adult epilepsy clinic. PATIENTS AND METHODS: Ophthalmological examination, consisting of questions about eye symptoms, study of the fundus oculi, Humphrey-type campimetry, protocol 30-2, visual evoked potentials and electroretinogram were done on a group of 10 patients on long-term vigabatrin treatment. RESULTS: Six of the ten patients (60%) had campimetric alterations, which were serious in two cases (20%). Only the two patients with severe field defects complained of sight changes when questioned and their complaints were mainly of repeatedly bumping into things. In two patients (20%) there was pallor of the optic nerve. In both cases, the patients with severe field defects showed alterations on the electroretinogram. Visual evoked potentials were normal in all cases. CONCLUSIONS: There is a very high prevalence of visual field defects in patients on long-term treatment with vigabatrin. Clinical ophthalmological signs are not usually seen until advanced stages. Pallor of the optic nerve was seen in a group of patients. It is very important that serial campimetric studies are done for early detection of such alterations.