Andhra Pradesh Eye Disease Study Research Articles

Incidence of primary open angle glaucoma in the Andhra Pradesh Eye Disease Study (APEDS)

Incidence of primary open angle glaucoma in the Andhra Pradesh Eye Disease Study (APEDS)

Visual impairment and blindness due to retinitis pigmentosa in India: 15-year follow-up of the Andhra Pradesh Eye Disease Study cohort.

To assess the incidence, visual impairment, and blindness due to retinitis pigmentosa (RP) in a rural southern Indian cohort. This is a population-based longitudinal cohort study of participants with RP from the Andhra Pradesh Eye Disease Study (APEDS) cohorts I and III, respectively. The study included participants with RP of APEDS I who were followed until APEDS III. Their demographic data along with ocular features, fundus photographs, and visual fields (Humphrey) were collected. Descriptive statistics using mean ± standard deviation with interquartile range (IQR) were calculated. The main outcome measures were RP incidence, visual impairment, and blindness as per the World Health Organization (WHO) definitions. At baseline (APEDS I), 7771 participants residing in three rural areas were examined. There were nine participants with RP with a mean age at baseline of 47.33 ± 10.89 years (IQR: 39-55). There was a male preponderance (6:3), and the mean best-corrected visual acuity (BCVA) of 18 eyes from nine participants with RP was 1.2 ± 0.72 logarithm of minimum angle of resolution (logMAR; IQR: 0.7-1.6). Over a mean follow-up duration of 15 years, 5395/7771 (69.4%) were re-examined, which included seven RP participants from APEDS 1. Additionally, two new participants with RP were identified; so, the overall incidence was 370/ million in 15 years (24.7/million per year). The mean BCVA of 14 eyes of seven participants with RP who were re-examined in APEDS III was 2.17 ± 0.56 logMAR (IQR: 1.8-2.6), and five of these seven participants with RP developed incident blindness during the follow-up period. RP is a prevalent disease in southern India that warrants appropriate strategies to prevent this condition.

Regional variation in the incidence of pseudo-exfoliation in the Andhra Pradesh Eye Disease Study (APEDS).

To report the 15-year incidence rate of pseudo-exfoliation (PXF), PXF glaucoma and regional variation among rural participants in the Andhra Pradesh Eye Disease Study (APEDS) III. This population-based longitudinal study was carried out at three rural study sites. Individuals of all ages who participated at baseline with amean 15-year follow-up visit were included. DetailedComprehensiveophthalmic examination was performed on all participants. The main outcome measure was development of PXF during the follow-up period in participants who were phakic in one or both eyeswithout PXF at baseline. Among 5395 participants, 5108 (94.6%) met the inclusion criteria. There were 93 (1.82%; 95% confidence interval (CI), 1.47-2.22) cases of incident PXF. Their median baseline age (1st, 3rd quartiles) was 51 (44, 59) years and the male: female ratio was 1.3:1. There was no case of incident PXF in participants aged <30 years at baseline. The incidence rate per 100 person years (95% CI) among all ages and those aged ≥30 years at baseline was 1.73 (1.64-1.82) and 3.73 (3.53-3.93), respectively. PXF material was located on iris as well as anterior surface of lens and itwas often bilateral. Participants living in two study sites and increasing age were associated with the incidence of PXF. The 15-year incidence of PXF glaucoma (95% CI) in participants ≥30 years of age at baseline was 0.33% (0.14-0.66). There is significant regional variation in incidence of PXF in south India which warrants further investigation.

Fifteen-Year Incidence Rate of Primary Angle Closure Disease in the Andhra Pradesh Eye Disease Study

To report on the 15-year incidence of primary angle closure disease (PACD) among participants aged ≥40 years in rural southern India DESIGN: Population-based longitudinal incidence rate study METHODS: Setting: 3 rural study centres. Phakic participants aged ≥40 years who participated in both examination time points. All participants at the baseline and at the mean 15-year follow-up visit underwent a detailed interview, anthropometry, blood pressure measurement, and comprehensive eye examination. Automated perimetry was attempted based on predefined criteria. Main outcome measures included development of any form of PACD, as defined by the International Society for Geographical and Epidemiological Ophthalmology (ISGEO), during the follow-up period in phakic participants, who did not have the disease at baseline. We analyzed data obtained from 1,197 (81.4% out of available 1,470) participants to calculate the incidence of the disease. The mean age (standard deviation) of the study participants at the baseline was 50.2 (8.1) years, with 670 male (45.5%) and 800 female (54.4%) participants. The incidence rate per 100 person-years (95% confidence interval) for primary angle closure suspect, primary angle closure, and primary angle closure glaucoma was 8.8 (8.4, 9.2), 6.2 (5.9, 6.6), and 1.6 (1.4, 1.8), respectively. Thus, the incidence of all forms of PACD was 16.4 (15.9, 17) per 100 person-years. On logistic regression analysis, female gender was a significant risk factor whereas presence of myopia was protective. This study reports long-term incidence of PACD from rural India. It has implications for eye health care policies, strategies, and planning.

Incidence, Incident Causes, and Risk Factors of Visual Impairment and Blindness in a Rural Population in India: 15-Year Follow-up of the Andhra Pradesh Eye Disease Study

To report 15-year incidence rate of visual loss (blindness and visual impairment [VI]), causes, and risk factors for participants in Andhra Pradesh Eye Disease Study III (APEDS III). Population-based cohort study. From 2012 to 2016, all rural participants were interviewed and underwent a comprehensive eye examination, including dilated fundus examination and imaging. Presenting visual acuity (PVA) and best-corrected visual acuity (BCVA) were measured using a standard logarithm of Minimum Angle of Resolution chart at 3 meters. World Health Organization (WHO) and United States of America (USA) categories of VI and blindness were used. Incident visual loss was defined as the development of or worsening of visual loss of one or more categories. In APEDS I, 7,771 rural participants were examined using stratified, random-cluster systematic sampling; in APEDS III, 5,395 participants (69.4% of rural or 52.4% of total participants) were re-examined. Using WHO categories, the crude incidence rate of any visual loss based on PVA and BCVA were 14.6 (95% confidence interval [CI]:13.6-15.7) and 6.3 (95% CI: 6.1-6.4) per 100 person-years, respectively. Using USA criteria, the values were 22.6 (95% CI: 22.3-23.0) and 10.6 (95% CI: 10.3-10.8) per 100 person-years, respectively. More than 90% of visual loss was attributable to cataract and uncorrected refractive error. Using WHO categories, significant independent risk factors for the incident visual loss were increasing age, female gender, illiteracy, past or current smoker, and current use of alcohol. Using the USA definition, an additional risk factor was lower level of education. The high incidence likely reflects poor access to eye care in this population, which needs to be taken into account when planning eye care programs.

Fifteen-year incidence rate and risk factors of pterygium in the Southern Indian state of Andhra Pradesh

PurposeTo report 15-year incidence rate and associated risk factors of pterygium among people aged 30 years and above at baseline in the rural clusters of longitudinal Andhra Pradesh Eye Disease...

Glaucoma-associated long-term mortality in a rural cohort from India: the Andhra Pradesh Eye Disease Study

AimTo evaluate glaucoma-associated mortality in a rural cohort in India.MethodsThe study cohort comprised individuals aged 40 years and above who took part in the Andhra Pradesh Eye Disease Study (APEDS1)...

Utilization of eye care services among those with unilateral visual impairment in rural South India: Andhra Pradesh Eye Disease Study (APEDS).

To report on the utilization of eye care services and its associated factors among those with unilateral visual impairment (VI) in a rural South Indian population. A population based cross-sectional study was conducted in three districts (Adilabad, Mahbubnagar and West Godavari) in the state of Andhra Pradesh, India. A detailed interview and a comprehensive eye examination were conducted. Those with unilateral VI were asked questions about noticing any change in vision and on utilization of eye care services. The most important reason reported by the participant for not utilizing the services was used for the analysis. Multiple logistic regression models were used to examine the association between noticing a change in vision and socio-demographic variables such as age, gender, education and area of residence, severity and causes of VI. Among the 4456 participants aged ≥16y who were administered the questionnaire, 53.2% were women, and 54.7% had no education. Of the 489 (11%; 95% CI: 10.1-11.9) people with unilateral VI, 399 (81.6%) participants reported noticing a change in their vision over the last five years but only 136 (34.1%) participants had sought eye care consultation. Those who had any education (OR: 1.9; 95% CI: 1.1-3.2), had blindness (OR: 2.7; 95% CI: 1.4-5.2), and cataract (OR: 2.1; 95% CI: 1.0-4.3) as a cause of unilateral VI were more like to seek eye care consultations. The most commonly reported reasons for not seeking eye care services were "do not have money for eye checkup" in 30.7% of the participants followed by "do not have a serious problem" (30.0%). A large proportion of rural population though noticed a change in their vision did not seek eye care due to financial and person-related reasons. Eye care service providers need to address these barriers to enhance the uptake of eye care services among those with unilateral VI.

Unilateral visual impairment in rural south India-Andhra Pradesh Eye Disease Study (APEDS).

To report the prevalence and causes of unilateral visual impairment (UVI) in rural population of all ages in rural Andhra Pradesh, India. A population-based cross sectional study using a multi-stage cluster sampling methodology was carried out in West Godavari, Adilabad and Mahbubnagar districts in south India. A comprehensive eye examination that included presenting and best corrected visual acuity and dilated fundus examination was conducted by trained professionals. UVI is defined as presenting visual acuity <6/18 in one eye but ≥6/18 in other eye. Multiple logistic regression analysis was used to test association of UVI with socio-demographic risk factors. Data were analyzed for 6634/7771 participants after excluding those with bilateral visual impairment. The mean age of the participants was 27.4y (standard deviation: 17.9y), 51.9% were women and 49.1% were educated. The prevalence of UVI was 7.8% (95% CI: 7.2%-8.5%). Uncorrected refractive error (60.8%), cataract (17.4%) and retinal causes (6.6%) were the leading causes of UVI. On multiple logistic regression analyses, older age, not having education, living in well-off district had significantly higher odds of being associated with UVI. UVI was not associated with gender. UVI is common in rural south India. Most of it is due to cataract and refractive errors, both of which can be addressed at primary and secondary levels of eye care. Burden of UVI should also be considered in planning eye care services.

Longitudinal Andhra Pradesh Eye Disease Study: rationale, study design and research methodology.

The rationale, objectives, study design and procedures for the longitudinal Andhra Pradesh Eye Disease Study are described. A longitudinal cohort study was carried out. Participants include surviving cohort from the rural component of Andhra Pradesh Eye Disease Study. During 1996-2000, Andhra Pradesh Eye Disease Survey was conducted in three rural (n = 7771) and one urban (n = 2522) areas (now called Andhra Pradesh Eye Disease Study 1). In 2009-2010, a feasibility exercise (Andhra Pradesh Eye Disease Study 2) for a longitudinal study (Andhra Pradesh Eye Disease Study 3) was undertaken in the rural clusters only, as urban clusters no longer existed. In Andhra Pradesh Eye Disease Study 3, a detailed interview will be carried out to collect data on sociodemographic factors, ocular and systemic history, risk factors, visual function, knowledge of eye diseases and barriers to accessing services. All participants will also undergo a comprehensive eye examination including photography of lens, optic disc and retina, Optic Coherence Tomography of the posterior segment, anthropometry, blood pressure and frailty measures. Measures include estimates of the incidence of visual impairment and age-related eye disease (lens opacities, glaucoma and age-related macular degeneration) and the progression of eye disease (lens opacities and myopia) and associated risk factors. Of the 7771 respondents examined in rural areas in Andhra Pradesh Eye Disease Study 1, 5447 (70.1%) participants were traced in Andhra Pradesh Eye Disease Study 2. These participants will be re-examined. Andhra Pradesh Eye Disease Study 3 will provide data on the incidence and progression of visual impairment and major eye diseases and their associated risk factors in India. The study will provide further evidence to aid planning eye care services.

Cataract, Visual Impairment and Long-Term Mortality in a Rural Cohort in India: The Andhra Pradesh Eye Disease Study

BackgroundA large-scale prevalence survey of blindness and visual impairment (The Andhra Pradesh Eye Diseases Study [APEDS1]) was conducted between 1996-2000 on 10,293 individuals of all ages in three rural and one urban clusters in Andhra Pradesh, Southern India. More than a decade later (June 2009-March 2010), APEDS1 participants in rural clusters were traced (termed APEDS2) to determine ocular risk factors for mortality in this longitudinal cohort.Methods and FindingsMortality hazard ratio (HR) analysis was performed for those aged >30 years at APEDS1, using Cox proportional hazard regression models to identify associations between ocular exposures and risk of mortality. Blindness and visual impairment (VI) were defined using Indian definitions. 799/4,188 (19.1%) participants had died and 308 (7.3%) had migrated. Mortality was higher in males than females (p<0.001). In multivariable analysis, after adjusting for age, gender, diabetes, hypertension, body mass index, smoking and education status the mortality HR was 1.9 (95% CI: 1.5-2.5) for blindness; 1.4 (95% CI: 1.2-1.7) for VI; 1.8 (95% CI: 1.4-2.3) for pure nuclear cataract, 1.5 (95% CI: 1.1-2.1) for pure cortical cataract; 1.96 (95% CI: 1.6-2.4) for mixed cataract, 2.0 (95% CI: 1.4-2.9) for history of cataract surgery, and 1.58 (95% CI: 1.3-1.9) for any cataract. When all these factors were included in the model, the HRs were attenuated, being 1.5 (95% CI: 1.1-2.0) for blindness and 1.2 (95% CI: 0.9-1.5) for VI. For lens type, the HRs were as follows: pure nuclear cataract, 1.6 (95% CI: 1.3-2.1); pure cortical cataract, 1.5 (95% CI: 1.1-2.1); mixed cataract, 1.8 (95% CI: 1.4-2.2), and history of previous cataract surgery, 1.8 (95% CI: 1.3-2.6).ConclusionsAll types of cataract, history of cataract surgery and VI had an increased risk of mortality that further suggests that these could be potential markers of ageing.

Population-Based Assessment of Prevalence and Risk Factors for Pterygium in the South Indian State of Andhra Pradesh: The Andhra Pradesh Eye Disease Study

To describe the prevalence and risk factors for pterygium in a population-based sample of individuals aged 30 years and older in South Indian state of Andhra Pradesh. A cross-sectional study was conducted in one urban and three rural locations in which 10,293 subjects were examined. All the subjects underwent comprehensive eye examination and a detailed interview by trained professionals. Pterygium was defined as fleshy fibro vascular growth, crossing the limbus, and typically seen on the nasal conjunctiva in either eye. Data were analyzed for 5586 subjects who were aged 30 years and older at the time of participation. The mean age of the participants was 47.5 years (SD 13 years; range 30-102 years). In total, 46.4% were male, 56.7% had no education, 52.2% of them were involved in outdoor occupations, and 25% belonged to urban area. The prevalence of pterygium was 11.7% (95% confidence interval [CI]: 10.9-12.6). The multiple logistic regression analysis revealed significantly higher odds of pterygium among older age groups, rural residents (odds ratio [OR]: 1.8; 95% CI: 1.4-2.4; P > 0.01), and those involved in outdoor occupations (OR: 1.8; 95% CI: 1.5-2.2, P < 0.001). Education had a protective effect (OR: 0.6; 95% CI: 0.5-0.7; P < 0.001). Pterygium is common in the South Indian state of Andhra Pradesh. Exposure to sunlight is a significant modifiable risk factor. Protecting the eyes from sunlight may decrease the risk of pterygium. However, the important public health challenge is to encourage the use of this protection as a routine in developing countries such as India.

Changing trends in the prevalence of visual impairment, uncorrected refractive errors and use of spectacles in Mahbubnagar district in South India

Background/Aim:The Andhra Pradesh Eye disease Study (APEDS) was a conventional cross-sectional study conducted in four locations during 1996-2000. Ten years later, a Rapid Assessment of Refractive Errors (RARE) survey was conducted in one of the geographical regions. The prevalence of visual impairment (VI), uncorrected refractive error (URE), spectacles use obtained from both the surveys was compared.Settings and Design:Rural settings; cross-sectional studies.Materials and Methods:In both the surveys, distance visual acuity (VA) was assessed using a logMAR chart. Pinhole VA was assessed if presenting VA was <20/20 in APEDS and <20/40 in RARE. VI was defined as presenting VA <20/40 in the better eye. URE was defined as presenting VA <20/40 and improving to ≥20/40 with a pinhole.Statistical Analysis Used:Performed using Statistical Package for Social Sciences (SPSS). Chi square tests and t-test were used.Results and Conclusions:The results from a RARE survey with 3,095 subjects were compared with an APEDS dataset that had 1,232 subjects in the same age group of 15-49 years. The prevalence of VI has decreased from 9.5% (95% CI, 7.7-11.1) in APEDS to 2.7% (95% CI, 2.1-3.3) in RARE. Similarly, the prevalence of URE in the better eye decreased from 5.8% (95% CI, 4.5-7.1) to 2.3% (95% CI, 1.8-2.8). The usage of spectacles increased from 6.6% (95% CI, 5.2-8.0) to 9.7% (95% CI, 8.7-10.7). There is a decreasing trend in the prevalence of VI and URE in Mahbubnagar district in Andhra Pradesh over a decade.

Advances in technology helps in early detection of vision disorders

Advances in technology helps in early detection of vision disorders

A new look at the WHOQOL as health-related quality of life instrument among visually impaired people using Rasch analysis

To examine the psychometric characteristics of the World Health Organization quality of life instrument-modified Indian version (modified WHOQOL) and its subscales in adults with visual impairment (VI) using Rasch analysis. Cross-sectional data were of people aged ≥40 years with VI (n = 1,333) who responded to the modified WHOQOL in the Andhra Pradesh Eye Disease Study, India. Rasch analysis was used to explore the instrument and its subscales for key indices such as measurement precision by person separation reliability, PSR (i.e., discrimination between strata of participants' health-related QOL [HRQOL], recommended minimum value 0.8), unidimensionality (i.e., measurement of a single construct), and targeting (i.e., matching of item difficulty to participants' HRQOL). Rasch-guided iterative approach including category re-organization to enable threshold ordering and item deletion to overcome multidimensionality resulted in a unidimensional 9-item WHOQOL and a 6-item level of independence (LOI) subscale with adequate PSR (0.81 and 0.82, respectively). Targeting was sub-optimal for both (-1.58 logits for WHOQOL and -2.55 logits for the subscale). Remaining subscales were dysfunctional. The WHOQOL and LOI subscale can be improved and shortened, and the Rasch-revised versions are likely to assess the HROQL of VI patients best because of their brevity, reliability, and unidimensionality.

Changing trends in the prevalence of blindness and visual impairment in a rural district of India: Systematic observations over a decade

Context:Globally, limited data are available on changing trends of blindness from a single region.Aims:To report the changing trends in the prevalence of blindness, visual impairment (VI), and visual outcomes of cataract surgery in a rural district of Andhra Pradesh, India, over period of one decade.Settings and Design:Rural setting; cross-sectional study.Materials and Methods:Using a validated Rapid Assessment of Cataract Surgical Services (RACSS) method, population-based, cross-sectional survey was done in a rural district in the state of Andhra Pradesh, India. Two-stage sampling procedure was used to select participants ≥50 years of age. Further, a comparative analysis was done with participants ≥50 years from the previously concluded Andhra Pradesh Eye Disease Study (APEDS) study, who belonged to the same district.Statistical Analysis:Done using 11th version of Stata.Results:Using RACSS, 2160/2300 (93.9%) participants were examined as compared with the APEDS dataset (n=521). Age and sex adjusted prevalence of blindness in RACSS and APEDS was 8% (95% CI, 6.9–9.1%) and 11% (95% CI, 8.3–13.7%), while that of VI was 13.6% (95% CI, 12.2–15.1%) and 40.3% (95% CI, 36.1–44.5%), respectively. Cataract was the major cause of blindness in both the studies. There was a significant reduction in blindness following cataract surgery as observed through RACSS (17.3%; 95% CI, 13.5–21.8%) compared with APEDS (34%; 95% CI, 20.9–49.3%).Conclusion:There was a significant reduction in prevalence of blindness and VI in this rural district of India over a decade.

Integrated model of primary and secondary eye care for underserved rural areas: The L V Prasad Eye Institute experience

Blindness is a major global public health problem and recent estimates from World Health Organization (WHO) showed that in India there were 62 million visually impaired, of whom 8 million are blind. The Andhra Pradesh Eye Disease Study (APEDS) provided a comprehensive estimate for prevalence and causes of blindness for the state of Andhra Pradesh (AP). It also highlighted that uptake of services was also an issue, predominantly among lower socio-economic groups, women, and rural populations. On the basis of this analysis, L V Prasad Eye Institute (LVPEI) developed a pyramidal model of eye care delivery. This article describes the LVPEI eye care delivery model. The article discusses infrastructure development, human resource development, and service delivery (including prevention and promotion) in the context of primary and secondary care service delivery in rural areas. The article also alludes to opportunities for research at these levels of service delivery and the amenability of the evidence generated at these levels of the LVPEI eye health pyramid for advocacy and policy planning. In addition, management issues related to the sustainability of service delivery in rural areas are discussed. The article highlights the key factors required for the success of the LVPEI rural service delivery model and discusses challenges that need to be overcome to replicate the model. The article concludes by noting the potential to convert these challenges into opportunities by integrating certain aspects of the existing healthcare system into the model. Examples include screening of diabetes and diabetic retinopathy in order to promote higher community participation. The results of such integration can serve as evidence for advocacy and policy.

Glaucoma in India: Estimated Burden of Disease

Over the last decade the prevalence of glaucoma has been reported by the Vellore Eye Survey, Andhra Pradesh Eye Disease Study, Aravind Comprehensive Eye Survey, Chennai Glaucoma Study, and West Bengal Glaucoma Study. There have been some differences largely because of methodologic variations. We use the reported age and gender stratified prevalence estimates from these studies and the Indian population census estimates to calculate the number of persons with glaucoma or at risk of the disease in the country. On the basis of the available data, we estimate that there are approximately 11.2 million persons aged 40 years and older with glaucoma in India. Primary open angle glaucoma is estimated to affect 6.48 million persons. The estimated number with primary angle-closure glaucoma is 2.54 million. Those with any form of primary angle-closure disease could comprise 27.6 million persons. Most of those with disease are undetected and there exist major challenges in detecting and treating those with disease. In the light of the existing manpower and resource constraints, we evaluate options for improving case detection rates in the country.

Angle Closure in the Andhra Pradesh Eye Disease Study

To estimate the prevalence and associated risk factors for primary angle-closure glaucoma (PACG), primary angle closure (PAC), and primary angle-closure suspects (PACS) in the Indian state of Andhra Pradesh. A population-based, cross-sectional study using a stratified, random, cluster, and systematic sampling strategy. Between 1996 and 2000, participants aged > or =40 years from 94 clusters in 1 urban and 3 rural areas were included. Trained professionals performed a detailed eye examination, including visual acuity, refraction, slit-lamp biomicroscopy, applanation tonometry, gonioscopy, and dilated fundus evaluation after ruling out risk of angle closure. Humphrey threshold 24-2 visual fields (VFs) were performed when indicated by disc criteria or if intraocular pressure (IOP) was > or =22 mmHg. Angle closure was diagnosed and categorized using International Society of Geographical and Epidemiological Ophthalmology criteria. Primary angle-closure glaucoma was present in 35 of 3724 subjects aged > or =40 years, an age- and gender-adjusted prevalence of 0.94% (95% confidence interval [CI], 0.63-1.24). Primary angle closure was present in 12 subjects (0.3%; 95% CI, 0.1-0.5), and PACS was present in 71 subjects (2%; 95% CI, 1.5-2.3). The prevalence of angle-closure disease (ACD=PACG+PAC) was 1.26% (95% CI, 0.90-1.62). Forty-one of 47 subjects (87.2%) with ACD were unaware of their disease. The prevalence of PACG increased from 0.56% (0.17-0.94) in the fourth decade to 2.5% (0.87-4.12) in the seventh decade. Seven (20%) of the 35 subjects with PACG were blind (visual acuity <3/60). Intraocular pressure increase (odds ratio [OR] 1.16; 95% CI, 1.11-1.22; P<0.001), diabetes mellitus (OR 3.18l; 95% CI, 1.34-7.58; P=0.001), and female gender (OR 2.07; 95% CI, 1.09-3.93; P=0.025) were significantly associated with angle-closure disease. No significant association was found with systemic hypertension (P=0.24) and hyperopia (P=0.05). The prevalence of PACG in this population was 0.94%. Increasing age, increasing IOP, diabetes mellitus, and female gender were significantly associated with angle-closure disease. Blindness due to PACG was 20%.

Prevalence and Risk Factors for Primary Glaucomas in Adult Urban and Rural Populations in the Andhra Pradesh Eye Disease Study

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. A population-based, cross-sectional study using a stratified, random, cluster, and systematic sampling strategy. Between 1996 and 2000, participants from 94 clusters in 1 urban and 3 rural areas representative of the population were included. 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. 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. 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). 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. The authors have no proprietary or commercial interest in any of the materials discussed in this article.