Topographical retinal function in oculocutaneous albinism

PURPOSE: Macular hypoplasia is the major ocular finding in albinism because it underlies reduced acuity and congenital nystagmus. Anatomic studies have shown a lack of foveal differentiation. However, functional anatomy of the macula in albinism is not known. DESIGN: Observational case reports. METHODS: We measured the topology of the retinal response in two patients with oculocutaneous albinism by using simultaneous fundus monitoring and multifocal electroretinographs (ERGs). Stimuli consisted of a 103-hexagon array centered on the macula. Recording conditions eliminated nystagmus artifact. RESULTS: ERG amplitudes were reduced only in the central 5 to 10 degrees compared with adult norms. When the response was scaled by stimulation area, multifocal ERG amplitudes were constant across all retinal eccentricities. CONCLUSIONS: The results suggest a homogeneous density of cone photoreceptors across the central retina in albinism, consistent with anatomic studies showing arrest of postnatal macular development. Further normative data are needed to fully quantify macular development in young children.