title: Association between asymmetry in cataract and asymmetry in age-related macular degeneration. The Beijing Eye Study.
abstract: BACKGROUND
  To examine in an intra-individual comparison whether cataract is associated with age-related macular degeneration (AMD).
  
  
  METHODS
  The population-based Beijing Eye Study included 4,439 subjects (age: 40+ years) out of 5,324 subjects invited to be examined. Using lens and fundus photographs, the amount of AMD was graded according to the Wisconsin Age-Related Maculopathy Grading system and the degree of cataract was graded using the system of the Age-Related Eye Disease Study.
  
  
  RESULTS
  Photographs with sufficient quality for bilateral examination of the lens and macula were available for 3,826 (86.2%) participants with a mean age of 55.3 ± 10.0 years (range: 40-90 years) and a mean refractive error of -0.38 ± 2.18 diopters (range: -20.13 diopters to +7.50 diopters). The side difference in presence of early AMD and late AMD respectively was not significantly associated with the inter-eye difference in the amount of nuclear cataract [P = 0.27 and P = 0.28 (r = 0.02) respectively), amount of cortical cataract (P = 0.12 and P = 0.05 respectively), and amount of subcapsular posterior cataract (P = 0.91 and P = 0.85 respectively). In a similar manner, the side difference in the presence of early AMD and late AMD was not significantly associated with the inter-eye difference in the presence of nuclear cataract (P = 0.99 and P = 0.99 respectively), cortical cataract (P = 0.25 and P = 1.00 respectively), and subcapsular posterior cataract (P = 0.59 and P = 0.05 respectively). The side difference in the number of macular drusen was not significantly associated with the inter-eye difference in the amount of nuclear cataract (P = 0.74), amount of cortical cataract (P = 0.19) and amount of subcapsular posterior cataract (P = 0.88). As a corollary, unilateral pseudophakia or aphakia was not significantly associated with inter-eye differences in the count (P = 0.59) of drusen, and overall presence of early AMD (P = 0.99) or late AMD (P = 0.99).
  
  
  CONCLUSIONS
  In an intra-individual, inter-eye comparison, avoiding interdependencies of systemic parameters, inter-eye difference was not significantly associated with any characteristics of age-related macular degeneration in either any type of cataract or in pseudophakia. This suggests that the development of cataract or cataract surgery did not markedly influence the development of age-related macular degeneration.
authors.affiliation: Beijing Institute of Ophthalmology, Beijing Tongren Hospital, Capital University of Medical Science, 17 Hougou Lane, Chong Wen Men, 100005, Beijing, China. xlbio@yahoo.cn
authors.forename: Liang
authors.initials: L
authors.lastname: Xu
authors.forename: Qi Sheng
authors.initials: QS
authors.lastname: You
authors.forename: Tongtong
authors.initials: T
authors.lastname: Cui
authors.forename: Jost B
authors.initials: JB
authors.lastname: Jonas
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002386:Cataract / Q000175:diagnosis / Q000453:epidemiology* / Q000503:physiopathology; D002681:China / Q000453:epidemiology; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008268:Macular Degeneration / Q000175:diagnosis / Q000453:epidemiology* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D012424:Rural Population; D014505:Urban Population