Low-carbohydrate diet optic neuropathy.

Visual loss occurring in two patients taking prolonged carbohydrate-restrictive diets is reported. The clinical data in these patients point to a specific diet deficiency of thiamine, causing a bilateral optic neuropathy. A discussion of current concepts of thiamine deficiency in neuroophthalmic disorders is presented. It is recommended that patients on low-carbohydrate diets for prolonged periods of time should receive thiamine supplements.