Prevalence and risk factors for primary glaucomas in adult urban and rural populations in the Andhra Pradesh Eye Disease Study

Purpose: To compare the prevalence of and risk factors for primary open-angle glaucoma (POAG) and primary angle-closure glaucoma (PACG) in urban and rural populations in the Andhra Pradesh Eye Disease Study.

Design: A population-based, cross-sectional study using a stratified, random, cluster, and systematic sampling strategy.

Participants: Between 1996 and 2000, participants from 94 clusters in 1 urban and 3 rural areas representative of the population were included.

Methods: We performed a detailed eye examination, including applanation tonometry, gonioscopy, and dilated fundus evaluation after ruling out risk of angle closure. Humphrey threshold 24-2 visual fields were performed when indicated.

Main outcome measures: Glaucoma was diagnosed and categorized using International Society of Geographical and Epidemiological Ophthalmology criteria. The prevalence and risk factors for POAG and PACG in subjects aged > or = 40 years were compared between the urban and rural cohorts.

Results: There were 3724 subjects > or = 40 years, with 934 in the urban and 2790 in the rural cohort. The prevalence of POAG was greater in the urban compared with the rural cohort (4% vs 1.6%; P<0.001). Age and intraocular pressure (IOP) were risk factors for POAG in both cohorts. Blindness owing to POAG was 11.1% in the rural and 2.7% in the urban cohort. The prevalence of PACG (1.8% vs 0.7%; P<0.01), primary angle closure (PAC) (0.8% vs 0.2%; P = 0.02) and primary angle closure suspect (PACS; 3.5% vs 1.5%; P<0.01) were significantly different between the urban and rural cohorts. Increasing age was a risk factor in the urban cohort. Intraocular pressure was a risk factor in both the populations. Blindness owing to PACG was equal (20%) in both the populations. Female gender was a risk factor in the rural cohort (P = 0.032).

Conclusions: The prevalence of both POAG and PACG was greater in urban than in the rural population. Intraocular pressure was a significant risk factor for both POAG and PACG in both cohorts. Increasing age was a significant risk factor for POAG in both cohorts and for PACG in the urban cohort. Female gender was a risk factor for PACG in the rural cohort. There was more blindness owing to PACG than to POAG.

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