Age norms for monocular grating acuity measured by sweep-VEP in the first three years of age.

PURPOSE To determine age norms for grating visual acuity and interocular acuity differences measured by the sweep-visually evoked potentials (VEP) technique in the first three years of life. METHODS Monocular grating visual acuity was measured using the sweep-VEP in 67 healthy normal infants and children in the first 36 months of life. RESULTS Sweep-VEP grating acuity ranged from 0.80 logMAR (20/125 Snellen equivalent) in the first month of life to 0.06 logMAR (20/20 Snellen equivalent) at 36 months of age. Lower normal limits (95th percentile limit) ranged from 0.95 logMAR (20/180) to 0.12 logMAR (20/25) with a progression of approximately 3 octaves in the first 36 months of age. The largest acceptable interocular acuity difference for clinical purposes was 0.10 logMAR. CONCLUSIONS Age norms for grating acuity along with interocular acuity differences were determined using the sweep-VEP technique. These norms should be incorporated in clinical practice for precise diagnosis of visual status in infants and preverbal children.