LCA is a disease in which there is little or no photoreceptor function in infancy; thereby, likely developmental in etiology ([17,56] for review). The Crx-/- mouse may be an excellent model for studying the pathology of this disorder, particularly the subtype of the disorder where Crx mutations are involved. The vast majority of histopathological studies of LCA in human tissue have been derived from adult patients with LCA where secondary changes are likely to be present. Indeed in animal models of LCA, secondary reactive and/or degenerative changes occur early after the abnormal formation of retinal tissue [57]. The only study in human tissue derived from a human 33-week retina with proposed RPE65 mutations was reported to have abnormal retinae at this early stage [24]. These authors report cell loss, including thinning of the photoreceptor layer. In addition, they claim in the text to have seen aberrant synaptic and inner retinal organization, although their examination of photoreceptor synapses unfortunately are not presented in the data section of the paper. Given the scarcity of available human tissue, the characterization of the primary pathology of LCA will require animal models. In the current study, we present data that argue that, in addition to outer segment morphogenesis, synaptogenesis may also be critically impaired in at least a subset of LCA.