Association between asymmetry in cataract and asymmetry in age-related macular degeneration. The Beijing Eye Study

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, intereye 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.