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Researchers from the INSERM Institut de la Vision, Paris, France have discovered that the sight-threatening side effects caused by the anti-epileptic drug vigabatrin may be caused by a drug-induced taurine deficiency. Furthermore, the scientists investigated the light-dependency of the damage caused by the drug. Epilepsy affects approximately 1% of the world’s population and especially in children, treatment modalities are highly restricted. The anticonvulsant vigabatrin, marketed under the name Sabril in France, is an effective treatment for epilepsy in children under 2 years of age. However, serious side effects may occur in 10–40% of patients and cause severe and irreversible impairment of the patient’s visual field. In animals, the drug induces a reduction in retinal cell function, retinal disorganization and cone photoreceptor damage. Taurine is an essential amino acid, which is supplemented by diet. Since previous results demonstrated that taurine deficiency leads to visual impairment, Serge Picaud and colleagues investigated, whether vigabatrin-induced impairment of vision can be associated to taurine deficiency. Therefore, rats and mice were treated with 40 and 3 mg vigabatrin, respectively. Retinal function of the animals was assessed by electroretinogram measurements and quantification of retinal disorganization, gliosis and cone receptor cell densities. Furthermore, the plasmalevels of 19 amino acids were determined. In order to assess the light-dependency of vigabatrin-induced visual impairment, a group of vigabatrin-treated animals were kept in the dark during treatment. In vigabatrin-treated animals that were kept in the dark, no retinal lesions could be determined. This clearly indicates the light-dependency of vigabatrin-induced visual impairment. Furthermore, the results showed that the taurine levels of vigabatrin-treated rats and mice were 67% lower than those of untreated animals, while concentrations of the other amino acids were identical in treated and untreated animals. By supplementing the diet of some vigabatrin-treated animals with taurine, an improvement of visual field-outcomes was obtained in these animals. Furthermore, Picaud and colleagues determined the plasma taurine levels of six vigabartin-treated infants. The plasma taurine levels of three of these children lay significantly below normal, while it was undetectable in two patients. After these results, the scientists propose solutions to limit the devastating effects vigabatrin can have on the patient’s vision. Serge Picaud claims, “In the first instance, care should therefore be taken to ensure that patients under vigabatrin consume a sufficient amount of food containing taurine. It is also important that they should be exposed to as little light as possible ... and should be induced to wear sunglasses”. Researchers stress every taurine supplementation should be subject to medical advice.