Leber Congenital Amaurosis (LCA)is a severe early onset retinal degeneration. Diagnosis is usually made during the first few months of life in infants who present with severely impaired vision, abnormal eye movements (nystagmus) and abnormal electroretinograms (ERG) indicating decreased retinal function. There is an inevitable progression to total blindness in these individuals due to death of photoreceptor cells. There is presently no treatment for this disease. The primary objective of this study is to determine the safety and tolerability of subretinal administration of AAV2-hRPE65v2 to subjects with Leber congenital amaurosis due to RPE65 mutations. The secondary objective is to assess the objective clinical measures of efficacy in human subjects.