Prevalence of cataract in Australia - The Blue Mountains Eye Study

Purpose: The authors determined the age and gender-specific prevalence of nuclear, cortical, and posterior subcapsular cataract (PSC) in a representative sample of older Australians. Methods: As part of a population-based study of eye disease in the Blue Mountains, west of Sydney, 3654 people aged 49 to 96 years underwent a detailed eye examination, including lens photography (slit-lamp and retroillumination). The photographs were assessed by masked graders using the Wisconsin Cataract Grading System, with acceptable reproducibility. Results: Past cataract surgery had been performed in either eye of 6.0% and in both eyes of 2.9% of participants in this study, equally in men and women. Moderate or advanced nuclear opacities were present in 53.3% of women and 49.7% of men. Moderate cortical cataract was present in 25.9% of women and 21.1% of men. Posterior subcapsular cataract was less frequent, found in 6.2% of women and 6.5% of men, After adjusting for age, these gender differences were statistically significant only for cortical cataract. The age-specific prevalence rates found for early and late cataract or for past cataract surgery are very similar to rates reported in the Beaver Dam Eye Study (BDES), Wisconsin, using the same definitions. Comparison of age-specific rates for each cataract type indicated lower rates for nuclear cataract, slightly lower rates for PSC and slightly higher rates for cortical cataract compared with the BDES. However, the rates for nuclear cataract were the only statistically significant differences between the two studies. Previously described susceptibility of the lower nasal lens to cortical cataract was confirmed, supporting a potential role of sunlight exposure in its development. Conclusions: The Wisconsin cataract grading system was used in an older Australian population with acceptable reproducibility. The Blue Mountains Eye Study found similar age-specific prevalence rates for most of the types and stages of cataract compared with the BDES.