Visual acuity of infants and children with retinal degenerations.

Visual acuity for gratings was studied in 18 infants and children with generalized retinal degenerations using preferential looking (PL) procedures. Diagnoses were Leber's congenital amaurosis (12), Laurence-Moon-Bardet-Biedl-like syndromes (4) and metabolic disorders (2). ERG's were extinguished in 11 patients and much attenuated in seven patients. Acuities at all ages (two months to 12 years) were significantly poorer than normal, and patients with extinguished ERG's had the poorest acuity. Neurological abnormality or mental retardation, present in ten patients, was as likely in patients with 6/60 or poorer grating acuity as in patients with better than 6/60 acuity. A comparison group of 12 infants and children with oculocutaneous albinism showed significantly better grating acuities than the patients with retinal degeneration. Relatively good grating acuity in infants with no anatomic fovea (oculocutaneous albinism) and much poorer acuities of infants with generalized retinal degeneration suggest that parafoveal or peripheral retina is necessary and sufficient for normal, behaviorally-obtained grating acuity in infancy.