4. Lack of sufficient viable retinal cells as determined by non-invasive means, such as optical coherence tomography (OCT) and/or ophthalmoscopy. Specifically, if indirect ophthalmoscopy reveals less than 1 disc area of retina which is not involved by complete retinal degeneration (indicated by geographic atrophy, thinning with tapetal sheen, or confluent intraretinal pigment migration), these eyes will be excluded. In addition, in eyes where optical coherence tomography (OCT) scans of sufficient quality can be obtained, areas of retina with thickness measurements less than 100 um, or absence of neural retina, will not be targeted for delivery of AAV2-hRPE65v2.