Prevalence of Primary Open-angle Glaucoma in an Urban South Indian Population and Comparison with a Rural Population: The Chennai Glaucoma Study
Presented in part at: 21st Congress of the Asia Pacific Academy of Ophthalmology, June 2006, Singapore.
Received 4 November 2006; received in revised form 8 April 2007; accepted 17 April 2007. published online 02 August 2007.
Objective
To estimate the prevalence and risk factors of primary open-angle glaucoma (POAG) in an urban population and compare the same with that of our published rural population data in southern India.
Design
Population-based cross-sectional study.
Participants
Four thousand eight hundred subjects 40 years or older were selected using a multistage random cluster sampling procedure in Chennai city.
Intervention
Three thousand eight hundred fifty (80.2%) subjects underwent a complete ophthalmic examination, including applanation tonometry, gonioscopy, pachymetry, optic disc photography, and automated perimetry.
Main Outcome Measures
Glaucoma was diagnosed using the International Society of Geographical and Epidemiological Ophthalmology Classification.
Results
The distribution of intraocular pressure (IOP) and vertical cup-to-disc ratio (VCDR) was obtained from the right eye of the 2532 subjects with normal suprathreshold visual fields. Mean IOP was 16.17±3.74 mmHg (97.5th and 99.5th percentiles, 24 mmHg and 30 mmHg). The mean VCDR was 0.43±0.17 (97.5th and 99.5th percentiles, 0.7 and 0.8). One hundred thirty-five (64 men, 71 women) subjects had POAG (3.51%; 95% confidence interval [CI], 3.04–4.0). Primary open-angle glaucoma subjects (58.4±11.3 years) were older (P<0.0001) than the study population (54.8±10.6 years). One hundred twenty-seven (94%) subjects were diagnosed to have POAG for the first time. Two subjects (1.5%) were bilaterally blind, and 3 (3.3%) were unilaterally blind due to POAG. The urban population prevalence was more than that of the rural population (1.62%; 95% CI, 1.4%–1.8%; P<0.0001). In both populations, increasing IOP (per millimeter of mercury) and older age were associated with the disease. There was no association with gender, myopia, systemic hypertension, diabetes, or central corneal thickness.
Conclusions
The prevalence of POAG in a ≥40-year-old south Indian urban population was 3.51%, higher than that of the rural population. The prevalence increased with age, and >90% were not aware of the disease.
Available online: July 30, 2007
1Glaucoma Project, Vision Research Foundation, Sankara Nethralaya, Chennai, India.
2Marshfield Clinic Research Foundation, Marshfield, Wisconsin.
Reprint requests to Dr L. Vijaya, Medical Research Foundation, Sankara Nethralaya, 18, College Road, Chennai, India–600006.
Manuscript no. 2006-1273.
Financial support: Chennai Willingdon Corporate Foundation, Chennai, India.
ABSTRACT