Elsevier

Ophthalmology

Volume 115, Issue 4, April 2008, Pages 648-654.e1
Ophthalmology

Original article
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.
https://doi.org/10.1016/j.ophtha.2007.04.062Get rights and content

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.

Section snippets

Study Design and Population

The details of the study design and sampling plan were published elsewhere.1 In brief, the Chennai Glaucoma Study was designed to estimate the prevalence of glaucoma. A sample size of 4758 was arrived at assuming an 85% response rate for an assumed 3% population prevalence of glaucoma with a relative precision of 25% and a design effect of 2. Therefore, 4800 subjects each from the rural and urban populations were enumerated. Sample selection for the urban component of the study was done using a

Results

A total of 3850 subjects of the enumerated 4800 participated in the study (response rate, 80.2%). One thousand seven hundred ten (44.4%) were male, and 2140 (55.6%) were female. The mean age of the study population was 54.8±10.6 years (range, 40–103). Of 950 nonparticipants (19.8%), 577 were male (60.7%) and 373 (39.3%) were female. There were 2532 subjects with normal and reliable suprathreshold VF testing using frequency-doubling perimetry in both eyes. Using the right eye of these subjects,

Discussion

The main purpose of the Chennai Glaucoma Study was to estimate the prevalence of glaucoma in rural and urban populations in southern India. Interesting findings in the present study are a higher prevalence of POAG in the urban population and differences between the rural and urban populations in various parameters. The age- and gender-adjusted prevalence of POAG in the urban population was 3.47% (95% CI, 2.9%–4.1%). There was a significant increase in prevalence of POAG with age, and there was

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      Citation Excerpt :

      For example, when diagnostic criteria from different large epidemiological studies were applied to one analytical dataset, prevalence estimates varied by up to 10-fold (Wolfs et al., 2000). To address this issue, the International Society for Geographical and Epidemiological Ophthalmology (ISGEO) published a consensus definition of POAG for epidemiological studies (Foster et al., 2002), and a growing number of studies now report according to this classification (Casson et al., 2007; He et al., 2006; Iwase et al., 2004; Jonasson et al., 2003; Rahman et al., 2004; Raychaudhuri et al., 2005; Shen et al., 2008; Sia et al., 2010; Vijaya et al., 2005, 2008; Wang et al., 2010). However, even comparisons between ISEGO-compliant studies are not straight-forward due to lack of standardisation of prevalence, particularly for age.

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    Manuscript no. 2006-1273.

    Financial support: Chennai Willingdon Corporate Foundation, Chennai, India.

    No conflicting interests.

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