Comparison of age-specific cataract prevalence in two population-based surveys 6 years apart.
BACKGROUND
In this study, we aimed to compare age-specific cortical, nuclear and posterior subcapsular (PSC) cataract prevalence in two surveys 6 years apart.


METHODS
The Blue Mountains Eye Study examined 3654 participants (82.4% of those eligible) in cross-section I (1992-4) and 3509 participants (75.1% of survivors and 85.2% of newly eligible) in cross-section II (1997-2000, 66.5% overlap with cross-section I). Cataract was assessed from lens photographs following the Wisconsin Cataract Grading System. Cortical cataract was defined if cortical opacity comprised > or = 5% of lens area. Nuclear cataract was defined if nuclear opacity > or = Wisconsin standard 4. PSC was defined if any present. Any cataract was defined to include persons who had previous cataract surgery. Weighted kappa for inter-grader reliability was 0.82, 0.55 and 0.82 for cortical, nuclear and PSC cataract, respectively. We assessed age-specific prevalence using an interval of 5 years, so that participants within each age group were independent between the two surveys.


RESULTS
Age and gender distributions were similar between the two populations. The age-specific prevalence of cortical (23.8% in 1st, 23.7% in 2nd) and PSC cataract (6.3%, 6.0%) was similar. The prevalence of nuclear cataract increased slightly from 18.7% to 23.9%. After age standardization, the similar prevalence of cortical (23.8%, 23.5%) and PSC cataract (6.3%, 5.9%), and the increased prevalence of nuclear cataract (18.7%, 24.2%) remained.


CONCLUSIONS
In two surveys of two population-based samples with similar age and gender distributions, we found a relatively stable cortical and PSC cataract prevalence over a 6-year period. The increased prevalence of nuclear cataract deserves further study.
Tan
Ava Grace
AG
Centre for Vision Research, Westmead Millennium Institute, Department of Ophthalmology, University of Sydney, Westmead Hospital, Westmead, NSW, Australia. ava_tan@wmi.usyd.edu.au
Wang
Jie Jin
JJ
Rochtchina
Elena
E
Mitchell
Paul
P
D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D001315:Australia / Q000453:epidemiology; D002386:Cataract / Q000453:epidemiology*; D003430:Cross-Sectional Studies; D005260:Female; D006306:Health Surveys; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D017678:Sex Distribution