A young boy with visual loss: when diet makes the difference

We report the outcome of 3 years of arginine-restricted diet and vitamin B6 supplementation in a boy who presented with gyrate atrophy and bilateral cystoid macular edema. The diagnosis was made on the basis of clinical findings and increased plasma ornithine levels. Molecular genetic testing revealed a disease-causing homozygous mutation in the ornithine aminotransferase (OAT) gene. After 3 months of dietary modification and pyridoxine supplementation, visual acuity improved, and optical coherence tomography showed resolution of cystoid macular edema in both eyes. This anatomical and functional improvement was maintained during 3 years of follow-up.