Purpose: To report the association of optic atrophy with cobalamin C (cblC) disease.
Methods: Descriptive case reports on three patients, two of whom were siblings.
Results: All three patients with cblC disease exhibited bilateral optic atrophy with decreased visual acuity. Of the two siblings, the younger sister had received cobalamin supplements from birth and the mother had been given cobalamin supplements prenatally.
Conclusion: These three cases confirm the association of optic atrophy with cblC disease. Early treatment with cobalamin supplements does not appear to prevent the development of optic atrophy.