title: The critical period for surgical treatment of dense congenital bilateral cataracts.
abstract: BACKGROUND
  We examined the critical period for deprivation amblyopia in a cohort of patients with dense bilateral congenital cataracts to investigate the optimum timing for surgical treatment.
  
  
  METHODS
  Thirty-seven infants with dense bilateral congenital cataracts that were 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 a critical age exists after which outcome depends on delay, and (4) a bilinear model in which a critical age exists 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 (chi(2) = 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 to 31 weeks, visual acuity was independent the subject's age at surgery, averaging 20/80. Surgery after 4 weeks was associated with a greater prevalence of strabismus and nystagmus than surgery before 4 weeks, whereas surgery during the first 4 weeks was associated with a greater prevalence of secondary membrane formation and glaucoma.
  
  
  CONCLUSIONS
  We did not find a latent period for the treatment of children with dense bilateral congenital cataracts. Deprivation amblyopia may be minimized with early surgery for bilateral cataracts.
authors.affiliation: Retina Foundation of the Southwest, Dallas, Texas; Department of Ophthalmology, University of Texas Southwestern Medical School, Dallas, Texas.
authors.forename: Eileen E
authors.initials: EE
authors.lastname: Birch
authors.forename: Christina
authors.initials: C
authors.lastname: Cheng
authors.forename: David R
authors.initials: DR
authors.lastname: Stager
authors.forename: David R
authors.initials: DR
authors.lastname: Weakley
authors.forename: David R
authors.initials: DR
authors.lastname: Stager
mesh_terms: D000293:Adolescent; D000550:Amblyopia / Q000453:epidemiology / Q000503:physiopathology / Q000517:prevention & control*; D002386:Cataract / Q000151:congenital* / Q000453:epidemiology / Q000503:physiopathology; D002387:Cataract Extraction / Q000706:statistics & numerical data; D002648:Child; D002675:Child, Preschool; D003423:Critical Period, Psychological; D005500:Follow-Up Studies; D006801:Humans; D007223:Infant; D009759:Nystagmus, Pathologic / Q000453:epidemiology / Q000503:physiopathology / Q000517:prevention & control; D011183:Postoperative Complications / Q000453:epidemiology; D012307:Risk Factors; D013285:Strabismus / Q000453:epidemiology / Q000503:physiopathology / Q000517:prevention & control; D014792:Visual Acuity / Q000502:physiology