Amblyopia and Grating Acuity Deficits Measured by Sweep–VEP in Congenital Cataract

Abstract

Abstract: : Purpose: Congenital cataract can lead to permanent visual deficits if the appropriate treatment is not promptly provided during very early infancy. The purpose of this study is to investigate amblyopia and grating acuity deficits in children with late treatment for either unilateral or bilateral congenital cataract. Methods: Participants were 47 children neurologically normal who were treated for congenital cataract. Monocular grating acuity was measured by sweep–VEP at 4–32 months of age (mean=18.7±8.3; median=18.8) in 27 unilateral cases (27 eyes) and at 5.5–42 months of age (mean=14.8±10.0; median=11.7) in 20 bilateral cases (36 eyes). An additional group of 80 healthy children aged 0–36 months was also tested to provide a normative database. Cataract was surgically removed between 2–28 months of age (mean=12.2±6.1; median=12.2) in unilateral cases and between 1–18.4 months of age (mean=7.8±4.2; median= 7.4) in bilateral ones. Pre–operative cataract opacity was classified as mild, moderate and severe. Glasses were prescribed for all bilateral cases and for 20 unilateral. IOL was implanted in 7 unilateral patients. Amblyopia was determined by interocular acuity differences (IAD) and grating acuity deficit from mean normal was calculated from the normative database. Results: IADs ranged from 0.26 to 1.07 logMAR (mean=0.60±0.20; median=0.64) in unilateral cases and from 0–0.31 logMAR (mean=0.10±0.11; median=0.06) in bilateral ones. Amblyopia was statistically more severe (P=0.001) in unilateral (median=0.54 logMAR) than in bilateral cases (median=0.06logMAR). VA deficit from mean normal ranged from 0.35 to 1.06 logMAR (mean=0.71±0.18; median=0.73) in unilateral cases, and from 0.19 to 1.02 logMAR (mean=0.52±0.19; median=0.54) in bilateral cases. VA deficit was statistically more severe in unilateral than in bilateral cases (t=3.93, P=0.001). Correlation between opacity severity and VA deficit was found for both unilateral (r=0.43; P=0.03) and bilateral (r=0.60; P=0.00009) cases. There was no difference for both VA deficit and amblyopia between unilateral cases treated with glasses or IOL. Conclusions: Amblyopia and considerable visual acuity deficits were found in this cohort of patients treated for congenital cataract. Unilateral cases had more severe amblyopia and grating acuity deficits than bilateral ones. In this late treated group these visual outcomes are consistent with the age of surgery that exceeds the limits for optimal visual development.

Keywords: infant vision • amblyopia • visual development: infancy and childhood