The Critical Period for Surgical Treatment of Dense Congenital Bilateral Cataracts

Introduction Little is known about the optimum timing of surgery for dense congenital bilateral cataracts. We examined the critical period for deprivation amblyopia in a cohort of patients with dense bilateral congenital cataracts. Methods Thirty-seven infants with dense bilateral congenital cataracts extracted by 31 weeks of age were enrolled prospectively. Visual acuity outcome was assessed at ≥5 years of age. We statistically evaluated which of 4 models provided the best fit to the data: 1) no change in visual acuity outcome with delay in surgery, 2) linear decline of outcome with delay, 3) a bilinear model in which there is a critical age after which outcome depends on delay, and 4) a bilinear model in which there is a critical age before which outcome depends on delay. In addition, we reviewed medical records for associated adverse outcomes, including strabismus, nystagmus, secondary membrane formation, and glaucoma. Results A bilinear model with a critical age of 14 weeks fit the data better than a linear model (χ2=14.7; p<0.0006). During weeks 0-14, mean visual acuity decreased by 1 line with each 3 weeks delay in surgery. From 14-31 weeks, visual acuity was independent of age at surgery, averaging 20/80. Surgery after 4 weeks was associated with a higher prevalence of strabismus and nystagmus than surgery before 4 weeks while surgery during the first 4 weeks was associated with a higher prevalence of secondary membrane formation and glaucoma. Conclusion We did not find a latent period for treatment of children with dense bilateral congenital cataracts. Deprivation amblyopia may be minimized with early surgery for bilateral cataracts.