Aims To evaluate the prevalence of and factors associated with age-related macular degeneration (AMD) in a rural population of southwestern Japan.
Methods This population-based cross-sectional study of all residents aged 40 years or older was conducted on the island of Kumejima, Okinawa, Japan. Of 4632 eligible residents, 3762 completed a comprehensive questionnaire and underwent ocular examination (participant rate, 81.2%). A non-mydriatic fundus photograph was used to grade AMD lesions according to the Wisconsin protocol. Prevalence of AMD was calculated and factors associated with AMD were identified by logistic regression.
Results Of 3068 subjects with gradable photographs, 469 had early AMD and 4 had late AMD. Age-adjusted prevalence was 13.4% for any AMD, 13.3% for early AMD and 0.09% for late AMD. In multivariate analysis, any AMD was positively associated with age (OR 1.04 per year, 95% CI 1.03 to 1.05), male sex (OR 1.42, 95% CI 1.14 to 1.75) and history of cataract surgery (OR 1.35, 95% CI 1.00 to 1.82) and was negatively associated with longer axial length (OR 0.85 per millimetre, 95% CI 0.74 to 0.96). Early AMD similarly showed significant associations with these same factors.
Conclusions Prevalence of early or late AMD in a southwestern island population of Japan was 13.4% or 0.09%. Our data suggest relatively high prevalence for early AMD and low prevalence for late AMD in this sample of rural Japanese population. Significant factors associated with any or early AMD were mostly similar to that of previous studies.
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Contributors Substantial contributions to conception and design of the work: RO, YY, TI, SS, AI and MA. Acquisition, analysis or interpretation of data for the work: RO, YY, TI, MY, YO, SS, AI and MA. Drafting or revising the work critically for important intellectual content: RO, YY, TI, MY, YO, SS, AI and MA. All authors gave final approval of the version to be submitted and agreed to be accountable for all aspects of the work including accuracy or integrity of any part of the work.
Competing interests RO, personal fees from Novaltis, Kowa, Bayer and Santen, outside the submitted work. AI, personal fees from Topcon, Carl Zeiss Meditec, Santen, Alcon, Pfizer, Senju, Kowa and Otsuka, outside the submitted work; a patent Topcon licensed.
Patient consent Detail has been removed from this case description/these case descriptions to ensure anonymity. The editors and reviewers have seen the detailed information available and are satisfied that the information backs up the case the authors are making.
Ethics approval The Ethics Committee of Kumejima Town.
Provenance and peer review Not commissioned; externally peer reviewed.