Prevalence of primary angle closure and primary angle-closure glaucoma in a southwestern rural population of Japan: the Kumejima Study

Purpose: To determine the prevalence and ocular biometry of primary angle closure (PAC) and primary angle-closure glaucoma (PACG) in a rural population in southwestern Japan.

Design: Population-based cross-sectional study.

Participants: All residents aged 40 years or older in Kumejima, Okinawa, Japan.

Intervention: Of the 4632 residents 40 years of age or older, 3762 (participation rate, 81.2%) underwent a detailed ocular examination, including measurement of the best-corrected visual acuity, slit-lamp examination, Goldmann applanation tonometry, static and dynamic gonioscopy, undilated stereoscopic optic fundus photographs, autorefractometry, partial coherence laser interferometry, noncontact specular microscopy, and screening visual field (VF) testing using frequency-doubling technology. If glaucoma or related or other ocular disorders were suspected, the subject was referred for a definitive examination including VF testing with the 24-2 Swedish Interactive Thresholding Algorithm Standard program of the Humphrey Field Analyzer (Carl Zeiss Meditec, Dublin, CA).

Main outcome measures: Prevalence rates of primary angle-closure suspects (PACS), PAC, PACG, and PACG suspects.

Results: Under the standard definitions of the International Society of Geographical and Epidemiological Ophthalmology, the prevalence rates of PACS, PAC, and PACG were 8.8%, 3.7%, and 2.0%. Extending the diagnosis of PAC and PACG to include people with narrow but open angles and primary peripheral anterior synechiae, the prevalence rates of PAC and PACG increased to 6.0% and 2.2%, respectively. Hence, broadening the diagnostic categories in PAC and PACG increased the prevalence rates by 62% and 10%. Twenty-three subjects (0.6%; 95% confidence interval, 0.4%-0.9%) had a history of or were diagnosed with acute PAC. Older age, female gender, hyperopic refractive error, short axial length, and shallow anterior chamber depth were independent predictors of an occludable angle.

Conclusions: The prevalence of PACG in Kumejima (2.2%) was one of the highest reported in population-based studies, that is, 3.7 times higher than in the Tajimi Study carried out in an urban center located in the central area of the main island of Japan.

Financial disclosure(s): The author(s) have no proprietary or commercial interest in any materials discussed in this article.