Prevalence and associations of cataract in indigenous Australians within central Australia: the Central Australian Ocular Health Study

PURPOSE: To determine the prevalence and associations of cataract within the indigenous Australian population living in central Australia. METHODS: 1884 individuals aged > or =20 years, living in one of 30 remote communities within the statistical local area of 'central Australia' were recruited for this study. This equated to 36% of those aged > or =20 years and 67% of those aged > or =40 years within this district. Slit-lamp examination was performed. The degree and subtype of cataract was graded using the Lens Opacities Classification System III criteria. A cataract was defined as a nuclear opalescence > or =4.0, a cortical opacity > or =3.0, a posterior subcapsular opacity > or =2.0, a visual acuity worse than 6/12 or a visual acuity worse than 6/60 due to cataract. The prevalence of cataract in one or both eyes was presented for each of the definitions. RESULTS: Nuclear opalescence cataract was present in 13.5% (18.5% of those > or =40 years); cortical opacity cataract was present in 13.1% (17.7% of those > or =40 years); and posterior subcapsular cataract was present in 15.8% (21.0% of those > or =40 years). 12.6% of patients (17.3% of those > or =40 years) and 4.4% of patients (5.9% of those > or =40 years) had a cataract that resulted in a visual acuity of worse than 6/12 and worse than 6/60, respectively. All cataracts were associated with advancing age. Posterior subcapsular cataract was associated with self-reported diabetes. CONCLUSION: There is a higher prevalence of cataract among indigenous Australians living within remote central Australia compared with the non-indigenous population. Services for this population need to be designed with this in mind when planning resource allocation.