Abstract
BackgroundIn this study, we aimed to compare age-specific cortical, nuclear and posterior subcapsular (PSC) cataract prevalence in two surveys 6 years apart.MethodsThe 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 ≥ 5% of lens area. Nuclear cataract was defined if nuclear opacity ≥ 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.ResultsAge 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.ConclusionIn 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.
Highlights
In this study, we aimed to compare age-specific cortical, nuclear and posterior subcapsular (PSC) cataract prevalence in two surveys 6 years apart
Surgical intervention is an effective treatment for cataract and normal vision (> 20/40) can usually be restored with intraocular lens (IOL) implantation
Data from the Australian Health Insurance Commission has shown a steady increase in Medicare claims for cataract surgery [8]
Summary
We aimed to compare age-specific cortical, nuclear and posterior subcapsular (PSC) cataract prevalence in two surveys 6 years apart. In Australia, it is estimated that by the year 2021, the number of people affected by cataract will increase by 63%, due to population aging [7]. Cataract surgery with IOL implantation is currently the most commonly performed, and is, arguably, the most cost effective surgical procedure worldwide. A 2.6fold increase in the total number of cataract procedures from 1985 to 1994 has been documented in Australia [9]. The rate of cataract surgery per thousand persons aged 65 years or older has doubled in the last 20 years [8,9]. In the Blue Mountains Eye Study population, we observed a onethird increase in cataract surgery prevalence over a mean 6-year interval, from 6% to nearly 8% in two cross-sectional population-based samples with a similar age range [10]. Further increases in cataract surgery performance would be expected as a result of improved surgical skills and technique, together with extending cataract surgical benefits to a greater number of older people and an increased number of persons with surgery performed on both eyes
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