Under-reporting of road traffic injuries to the police: results from two data sources in urban India

OBJECTIVE

To report the magnitude of under-reporting of road traffic injury (RTI) to the police from population-based and hospital-based data in the urban population of Hyderabad, India.

METHODS

In a cross-sectional population-based survey, 10 459 participants aged 5-49 years (94.3% participation), selected using three-stage systematic cluster sampling, recalled the reporting of non-fatal RTIs to the police in the preceding 12 months and fatal RTIs in the preceding 3 years. In addition, 781 consecutive RTI cases presenting to the emergency department of five hospitals provided information on RTI reporting to the police.

RESULTS

In the population-based study, of those who had non-fatal RTIs and sought outpatient or inpatient services, 2.3% (95% 1.1% to 3.5%) and 17.2% (95% CI 3.5% to 30.9%), respectively, reported the RTI to the police. Of the non-fatal consecutive RTI cases presenting to emergency departments, 24.6% (95% CI 21.3% to 27.8%) reported the RTI to the police. In the population-based study, 77.8% (95% CI 65.1% to 90.5%) of the fatal RTIs were reported to the police, and of the consecutive fatal RTI cases presenting to emergency departments, 98.1% (95% CI 95.5% to 100%) were reported to the police. The major reasons cited for not reporting RTIs to the police were "not necessary to report" and "hit and run case".

CONCLUSIONS

As road safety policies are based on police data in India, these studies highlight serious limitations in estimating the true magnitude of RTIs from these data, indicating the need for better methods for such estimation.

The burden of fatal and non-fatal injury in rural India

BACKGROUND

Little is known about the burden or causes of injury in rural villages in India.

OBJECTIVE

To examine injury-related mortality and morbidity in villages in the state of Andhra Pradesh, India.

METHODS

A verbal-autopsy-based mortality surveillance study was used to collect mortality data on all ages from residents in 45 villages in 2003-2004. In early 2005, a morbidity survey in adults was carried out using stratified random sampling in 20 villages. Participants were asked about injuries sustained in the preceding 12 months. Both fatal and non-fatal injuries were coded using classification methods derived from ICD-10.

RESULTS

Response rates for the mortality surveillance and morbidity survey were 98% and 81%, respectively. Injury was the second leading cause of death for all ages, responsible for 13% (95% CI 11% to 15%) of all deaths. The leading causes of fatal injury were self-harm (36%), falls (20%), and road traffic crashes (13%). Non-fatal injury was reported by 6.7% of survey participants, with the leading causes of injury being falls (38%), road traffic crashes (25%), and mechanical forces (16.1%). Falls were more common in women, with most (72.3%) attributable to slipping and tripping. Road traffic injuries were sustained mainly by men and were primarily the result of motorcycle crashes (48.8%).

DISCUSSION

Injury is an important contributor to disease burden in rural India. The leading causes of injury-falls, road traffic crashes, and suicides-are all preventable. It is important that effective interventions are developed and implemented to minimize the impact of injury in this region.

Incidence and burden of road traffic injuries in urban India

BACKGROUND

The scale of road traffic injuries (RTIs) in India is uncertain because of limitations in the availability and reliability of incidence data.

OBJECTIVE

To report these data for Hyderabad city in southern India.

METHODS

In a cross-sectional population-based survey, 10 459 participants aged 5-49 years (94.3% participation), selected using three-stage systematic cluster sampling, were interviewed. Participants recalled RTIs in the preceding 3 months and RTI-related death and disability in the household in the preceding 3 years. RTI was defined as an injury resulting from a road traffic crash irrespective of the severity.

RESULTS

The age/sex-adjusted annual incidence of non-fatal RTI requiring a recovery period of < or =7, 8-29, and > or =30 days was 13% (95% CI 12.6% to 13.4%), 5.8% (95% CI 5.5% to 6.0%), and 1.2% (95% CI 1.1% to 1.4%), respectively. The overall adjusted rate for non-fatal RTI was 20.7% (95% CI 20.0% to 21.3%). The relative risk of RTI requiring a recovery period of >7 days was significantly higher in the third per capita monthly income quartile (1.24 (95% CI 1.12 to 1.37); p<0.05). The incidence of non-fatal RTI was highest in pedestrians, motorized two-wheeled vehicle users, and cyclists: 6.4, 6.3, and 5.1/100 persons/year, respectively. Annual RTI mortality and disability rates were 38.2 (95% CI 17.5 to 58.8) and 35.1 (95% CI 12.4 to 57.7) per 100,000 population, respectively.

CONCLUSIONS

There is a high burden of RTI in this urban population. With the recent attention focused on RTI by the Government of India, these findings may assist in planning appropriate initiatives to reduce the RTI burden.

Patterns of road traffic injuries in a vulnerable population in Hyderabad, India

OBJECTIVE

To describe patterns of road traffic injuries (RTI) in a vulnerable population-pedestrians and users of motorized two-wheeled vehicles (MTVs)-in Hyderabad, India.

METHODS

4019 pedestrians and 4183 MTV drivers provided information on the most recent road traffic crash (RTC) irrespective of the level of injury in the last one year for 17 454 and 17 242 household members, respectively. Crashes in which any household member was involved as a pedestrian or MTV user were analysed.

RESULTS

Involvement in an RTC as a pedestrian or MTV user was reported for 1513 (4.4%, 95% CI 4.2 to 4.6%) people in the last one year. In these crashes, the person involved was an MTV user in 1264 (83.5%), aged 21-40 years in 973 (64.3%), and male in 1202 (79.4%). Six (0.4%) people died in RTCs and the cause was collision with a vehicle/person in 1133 (75%) crashes. Among the 1306 people who were injured and survived, 174 (13.3%) were treated as inpatients, 38 (2.9%) could not return fully to routine daily activities, 630 (48.2%) took leave from their regular occupation, and 13 (1%) lost their jobs following injury. Using a three month recall period, the annual incidence per 100 000 population of RTC as a pedestrian or MTV user was 2288 and of non-fatal RTI was 1931, and that of fatal RTI using one year recall period was 17.3 in this population.

CONCLUSIONS

These findings on how RTI are caused, their type, and outcomes in pedestrians and MTV users can assist in identifying interventions to improve road safety for this vulnerable population in India, and can also be useful for monitoring the effectiveness of such interventions.

Childhood blindness in India: a population based perspective

AIM

To estimate the prevalence and causes of blindness in children in the southern Indian state of Andhra Pradesh.

METHODS

These data were obtained as part of two population based studies in which 6935 children <or=15 years of age participated. Blindness was defined as presenting distance visual acuity <6/60 in the better eye.

RESULTS

The prevalence of childhood blindness was 0.17% (95% confidence interval 0.09 to 0.30). Treatable refractive error caused 33.3% of the blindness, followed by 16.6% due to preventable causes (8.3% each due to vitamin A deficiency and amblyopia after cataract surgery). The major causes of the remaining blindness included congenital eye anomalies (16.7%) and retinal degeneration (16.7%).

CONCLUSION

In the context of Vision 2020, the priorities for action to reduce childhood blindness in India are refractive error, cataract related amblyopia, and corneal diseases.

Corneal blindness in a southern Indian population: need for health promotion strategies

AIM

To assess the distribution and causes of corneal blindness in a population in southern India.

METHODS

A total of 11 786 people of all ages from 94 clusters representative of the population of the Indian state of Andhra Pradesh were sampled using a stratified, random, cluster, systematic sampling strategy. These participants underwent a detailed interview and eye examination including measurement of visual acuity with logMAR charts, refraction, slit lamp biomicroscopy, applanation tonometry, gonioscopy, and stereoscopic dilated fundus evaluation. An eye was considered to have corneal blindness if the visual acuity was <20/200 due to a corneal disease.

RESULTS

Of those sampled, 10 293 (87.3%) people participated in the study. Corneal blindness in at least one eye was present in 86 participants, an age, sex, and urban-rural distribution adjusted prevalence of 0.66% (95% confidence interval 0.49 to 0.86), which included 0.10% prevalence of corneal blindness in both eyes and 0.56% in one eye. The most frequent causes of corneal blindness in at least one eye included keratitis during childhood (36.7%), trauma (28.6%), and keratitis during adulthood (17.7%). Nearly 95% of all corneal blindness was avoidable. Multivariate analysis showed that the prevalence of corneal blindness was significantly higher with decreasing socioeconomic status and with increasing age. Of the 99 eyes with corneal blindness, 51 (51.5%) had visual acuity of inaccurate projection of light or no perception of light.

CONCLUSIONS

There is a significant burden of corneal blindness in this population, the majority of which is avoidable. Eye health promotion strategies are warranted to raise awareness about the causes and prevention of corneal blindness.

Moderate visual impairment in India: the Andhra Pradesh Eye Disease Study

AIM

To assess the prevalence and demographic associations of moderate visual impairment in the population of the southern Indian state of Andhra Pradesh.

METHODS

From 94 clusters in one urban and three rural areas of Andhra Pradesh, 11 786 people of all ages were sampled using a stratified, random, cluster, systematic sampling strategy. The eligible people were invited for interview and detailed dilated eye examination by trained professionals. Moderate visual impairment was defined as presenting distance visual acuity less than 6/18 to 6/60 or equivalent visual field loss in the better eye.

RESULTS

Of those sampled, 10,293 (87.3%) people participated in the study. In addition to the previously reported 1.84% prevalence of blindness (presenting distance visual acuity less than 6/60 or central visual field less than 20 degrees in the better eye) in this sample, 1237 people had moderate visual impairment, an adjusted prevalence of 8.09% (95% CI 6.89 to 9.30%). The majority of this moderate visual impairment was caused by refractive error (45.8%) and cataract (39.9%). Increasing age, female sex, decreasing socioeconomic status, and rural area of residence had significantly higher odds of being associated with moderate visual impairment.

CONCLUSIONS

These data suggest that there is a significant burden of moderate visual impairment in this population in addition to blindness. Extrapolation of these data to the population of India suggests that there were 82 million people with moderate visual impairment in the year 2000, and this number is likely to be 139 million by the year 2020 if the current trend continues. This impending large burden of moderate visual impairment, the majority of which is due to the relatively easily treatable refractive error and cataract, would have to be taken into account while estimating the eye care needs in India, in addition to dealing with blindness. Specific strategies targeting the elderly population, people with low socioeconomic status, those living in the rural areas, and females would have to be implemented in the long term to reduce moderate visual impairment.

Review of findings of the Andhra Pradesh Eye Disease Study: policy implications for eye-care services

The Andhra Pradesh Eye Disease Study (APEDS) was conducted in order to design long-term strategies to reduce blindness in the background of non-availability of recent population-based data on various aspects of blindness. The objectives of APEDS were to determine the prevalence and causes of blindness and visual impairment, prevalence of and risk factors for major eye diseases, barriers to eye-care services, and quality of life among the visually impaired. Multistage sampling was used to select 11,786 subjects of all ages from 24 urban clusters and 70 rural clusters in one urban and three rural areas belonging to different parts of Andhra Pradesh, with the aim of obtaining a study sample representative of the urban-rural and socioeconomic distribution of the population of this state. A total of 10,293 subjects underwent a detailed interview and dilated eye examination by trained professionals. The adjusted prevalence of blindness (presenting visual acuity <6/60 or central visual field <20 degrees in the better eye) was 1.84%, and moderate visual impairment (presenting visual acuity <6/18-6/60 or equivalent visual field loss in the better eye) was 8.1%. Cataract and refractive error were responsible for 60.3% of blindness and 85.7% of moderate visual impairment. Increasing age, decreasing socioeconomic status, female gender, and rural area of residence were associated with higher risk of blindness. Projections from APEDS suggest that there were 18.7 million blind people in 2000 in India, and that this number is likely to increase to 24.1 million and 31.6 million in 2010 and 2020 respectively, if the current trend continues. This review summarizes the findings of APEDS and discusses the implications of these data on the policy and planning of eye-care services.

Estimation of blindness in India from 2000 through 2020: implications for the blindness control policy

BACKGROUND

To eliminate avoidable blindness in India, appropriate national planning is necessary, which should be based on current and reliable data. A national survey done in 1986-89 reported that 1.5% of the Indian population (12 million people) was blind with a presenting visual acuity of < 6/60 in the better eye. The original goal of the National Programme for Control of Blindness was to reduce this prevalence to 0.3% by 2000. We have recently reported the prevalence of blindness in the population of Andhra Pradesh to be 1.66% with a presenting visual acuity of < 6/60 in the better eye as the sole criterion and 1.84% with a presenting visual acuity of < 6/60 orcentral visual field < 20 degrees in the better eye. We used these population-based data to estimate blindness in India in 2000 and project the possible scenarios of blindness through 2020 with different emphases of the blindness control policy in India.

METHODS

Recent population-based data on the age-, sex- and cause-specific blindness rates from the Andhra Pradesh Eye Disease Study for the entire age range were applied to the population distribution of India to estimate the number of blind persons in 2000. The age-, sex- and cause-specific rates of blindness were then applied to the estimated age, sex and urban-rural population distribution of India in 2010 and 2020 to project the number of persons blind (from various causes) and the blind person-years that would be suffered under varying degrees of emphasis in the policy to control blindness due to particular diseases. For these projections, blindness was defined as a presenting distance visual acuity of < 6/60 or central visual field < 200 in the better eye.

RESULTS

The number of blind persons in India in 2000 was estimated to be 18.7 million (95% confidence interval [CI]: 15.2-22.3), of which 9.5 million were cataract-related and 3 million refractive error-related. If there is no change in the current trend of blindness, the number of blind persons in India would increase to 24.1 million (95% CI: 19.7-28.4) in 2010, and to 31.6 million (95% Cl: 26.4-36.9) in 2020. If effective strategies are put in place to eliminate 95% of blindness due to cataract by 2020, blindness in 15.6 million persons would be prevented who would otherwise be blind in 2020 if the current trend continues, and 78 million blind person-years would be prevented in these persons. Similarly, if effective strategies are also implemented to eliminate 95% of the refractive error blindness by 2020, another 4.2 million persons would be prevented from being blind in 2020, and 82 million blind person-years would be prevented. In addition, if strategies to prevent 90% of the preventable blindness due to corneal disease and glaucoma are successful by 2020, blindness in an additional 3.6 million persons in 2020 and 29 million blind person-years would be prevented.

CONCLUSION

The planning of blindness control in India should take into account recent population-based data for the entire age range, which suggest that the number of blind persons in India is currently over 18 million. This estimate is 50% more than the figure of 12 million from a decade ago that is still quoted widely in the blindness control policy documents. If avoidable blindness is to be substantially reduced in India by 2020, effective strategies against blindness due to cataract and refractive error are needed urgently as both these conditions are relatively easy to treat. Also, strategies against preventable corneal and glaucoma blindness need to be strengthened soon for them to show an impact over the next two decades.

Blindness in the Indian state of Andhra Pradesh

PURPOSE

To determine the current prevalence and causes of blindness in the Indian state of Andhra Pradesh to assess if blindness has decreased since the last survey of 1986-1989.

METHODS

A population-based epidemiology study, using a stratified, random, cluster, systematic sampling strategy, was conducted in the state of Andhra Pradesh in India. Participants of all ages (n = 10,293), 87.3% of the 11,786 eligible, from 94 clusters in one urban and three rural areas representative of the population of Andhra Pradesh, underwent interview and a detailed dilated ocular evaluation by trained professionals. Blindness was defined as presenting distance visual acuity < 6/60 or central visual field < 20(o) in the better eye.

RESULTS

Two hundred seventy-five participants were blind, a prevalence of 1.84% (95% confidence interval, 1.49%-2.19%) when adjusted for the age, sex, and urban-rural distribution of the population in 2000. The causes of this blindness were easily treatable in 60.3% (cataract, 44%; refractive error, 16.3%). Preventable corneal disease, glaucoma, complications of cataract surgery, and amblyopia caused another 19% of the blindness. Blindness was more likely with increasing age and decreasing socioeconomic status, and in female subjects and in rural areas. Among the 76 million population of Andhra Pradesh, 714,400 are estimated to have cataract-related blindness (615,600 cataract, 53,200 cataract surgery-related complications, 45,600 aphakia), and 228,000 refractive error-related blindness (159,600 myopia, 22,800 hyperopia, 45,600 refractive error-related amblyopia). If 95% of the cataract and refractive error blindness in Andhra Pradesh had been treated effectively, 3.4 and 7.4 million blind-person-years, respectively, could have been prevented. If 90% of the blindness due to preventable corneal disease and glaucoma had been prevented, another 2.7 million blind-person-years could have been prevented.

CONCLUSIONS

The prevalence of blindness in this Indian state has increased from 1.5% in the late 1980s to 1.84% currently, as against the target of the National Program for Control of Blindness to reduce the prevalence to 0.3% by 2000. The number of people with cataract-related blindness has not reduced even with the eye care policy focus on cataract. Reduction of blindness in India will require strategies that are more effective than those that have been pursued so far.

Planimetric optic disc parameters in normal eyes: a population-based study in South India

PURPOSE

To study the optic disc parameters of normal eyes in a population-based south Indian study.

METHODS

One hundred and fifty three subjects from a population-based sample of 1060 included in the Andhra Pradesh Eye Disease Survey (APEDS) were enrolled in the optic disc study. The male-female ratio, the refractive error and distribution of other ocular parameters in the disc study subjects and the APEDS were not significantly different. Magnification corrected morphometry of optic disc photographs obtained by Zeiss telocentric fundus camera was carried out in one randomly chosen eye of each of these 143 subjects.

RESULTS

The mean optic disc parameters with the 95% confidence intervals for the distribution were: disc area 3.37 mm2 (2.04 - 4.7), vertical disc diameter 2.12 mm (1.67 - 2.57), vertical cup to disc ratio 0.37 (0.19 -0.55) and neuroretinal rim area 2.8 mm2 (1.76 - 3.84). The disc area, the vertical cup to disc ratio and the rim area showed a normal distribution. The cup to disc ratio correlated with the vertical disc diameter but the association was not strong.

CONCLUSION

The disc area, the vertical cup to disc ratio and the neuroretinal rim area are normally distributed in the South Indian population. The normal optic disc parameters would form a basis for future comparisons in different forms of glaucoma.

Awareness of eye diseases in an urban population in southern India

OBJECTIVE

To assess the level of awareness of eye diseases in the urban population of Hyderabad in southern India.

METHODS

A total of 2522 subjects of all ages, who were representative of the Hyderabad population, participated in the population-based Andhra Pradesh Eye Disease Study. Of these subjects, 1859 aged > 15 years responded to a structured questionnaire on cataract, glaucoma, night blindness and diabetic retinopathy to trained field investigators. Having heard of the eye disease in question was defined as "awareness" and having some understanding of the eye disease was defined as "knowledge".

FINDINGS

Awareness of cataract (69.8%) and night blindness (60.0%) was moderate but that of diabetic retinopathy (27.0%) was low, while that of glaucoma (2.3%) was very poor. Knowledge of all the eye diseases assessed was poor. Subjects aged > or = 30 years were significantly more aware of all eye diseases assessed except night blindness. Multivariate analysis revealed that women were significantly less aware of night blindness (odds ratio (OR) = 0.78; 95% confidence interval (CI) = 0.63-0.97). Education played a significant role in awareness of these eye diseases. Study subjects of upper socioeconomic status were significantly more aware of night blindness (OR = 2.20; 95% CI = 1.29-3.74) and those belonging to upper and middle socioeconomic strata were significantly more aware of diabetic retinopathy (OR = 2.79; 95% CI = 2.19-3.56). Muslims were significantly more aware of cataract (OR = 2.36; 95% CI = 1.84-3.02) and less aware of night blindness (OR = 0.52; 95% CI = 0.42-0.64). The major source of awareness of the eye diseases was a family member/friend/relative suffering from that eye disease.

CONCLUSION

These data suggest that there is a need for health education in this Indian population to increase their level of awareness and knowledge of common eye diseases. Such awareness and knowledge could lead to better understanding and acceptance of the importance of routine eye examinations for the early detection and treatment of eye diseases, thereby reducing visual impairment in this population.

Refractive error blindness

Recent data suggest that a large number of people are blind in different parts of the world due to high refractive error because they are not using appropriate refractive correction. Refractive error as a cause of blindness has been recognized only recently with the increasing use of presenting visual acuity for defining blindness. In addition to blindness due to naturally occurring high refractive error, inadequate refractive correction of aphakia after cataract surgery is also a significant cause of blindness in developing countries. Blindness due to refractive error in any population suggests that eye care services in general in that population are inadequate since treatment of refractive error is perhaps the simplest and most effective form of eye care. Strategies such as vision screening programmes need to be implemented on a large scale to detect individuals suffering from refractive error blindness. Sufficient numbers of personnel to perform reasonable quality refraction need to be trained in developing countries. Also adequate infrastructure has to be developed in underserved areas of the world to facilitate the logistics of providing affordable reasonable-quality spectacles to individuals suffering from refractive error blindness. Long-term success in reducing refractive error blindness worldwide will require attention to these issues within the context of comprehensive approaches to reduce all causes of avoidable blindness.

Ocular trauma in an urban population in southern India: the Andhra Pradesh Eye Disease Study

PURPOSE

To assess the cumulative prevalence of ocular trauma and presence of vision loss due to ocular trauma in an urban population in southern India.

METHODS

As part of the population-based Andhra Pradesh Eye Disease Study, 2522 people of all ages from 24 clusters representative of the population of Hyderabad city in southern India, underwent a detailed interview and standardized dilated ocular evaluation. An eye was considered to be blind due to trauma if best corrected distance visual acuity was worse than 6/60 due to trauma.

RESULTS

One hundred and thirteen subjects gave a history of ocular trauma and another two had evidence of ocular trauma by examination, a combined age sex-adjusted rate of 3.97% (95% CI 2.52-5.42%). Blindness in one eye due to trauma was present in 17 subjects, and in both eyes in one subject, a combined age-sex-adjusted prevalence of 0.60% (95% CI 0.23-1.04%). Visual acuity in all the blind eyes except one was worse than 3/60. With multiple logistic regression, the odds of blindness in at least one eye due to trauma were highest for current age range of 30-39 years (odds ratio 6.33, 95% CI 1.69-23.77 compared with a current age of less than 30 years), were significantly higher for lower socioeconomic status (3.74, 95% CI 1.18 -11.84), and were higher for males (2.48, 95% CI 0.91-6.82) though this did not reach statistical significance. Trauma resulting in blindness had occurred by the age of 15 years in 55% of subjects, and before the age of 40 years in 92.1% of subjects; this had occurred most commonly while playing (53.6% of the cases). With multiple logistic regression, the odds ratios for any ocular trauma were significantly higher for males (2.10, 95% CI 1.40-3.15), and for labourers than for other occupations (2.50, 95% CI 1.62-3.86).

CONCLUSIONS

Ocular trauma affects one in 25 people in this urban population in India, and one in 167 people in this population are estimated to be blind in at least one eye due to trauma. The majority of the trauma resulting in blindness occurs during childhood and young adulthood, and slightly more than half occurs while playing. Targeting mothers and children of lower socioeconomic strata in eye health awareness strategies to reduce blindness due to trauma needs to be considered in urban India.

Angle-closure glaucoma in an urban population in southern India. The Andhra Pradesh eye disease study

OBJECTIVE

To assess the prevalence and features of angle-closure glaucoma (ACG) in an urban population in southern India.

DESIGN

A population-based, cross-sectional study.

PARTICIPANTS

A total of 2522 (85.4% of those eligible) persons of all ages, including 1399 persons 30 years of age or older, from 24 clusters representative of the population of Hyderabad city.

TESTING

The participants underwent an interview and detailed eye examination that included logarithm of minimum angle of resolution visual acuity, refraction, slit-lamp biomicroscopy, applanation tonometry, and gonioscopy; pupil dilatation and stereoscopic fundus evaluation was performed if the risk of angle-closure as a result of dilatation was not believed to be imminent. Humphrey threshold 24-2 visual fields (Humphrey Instruments Inc., San Leandro, CA) were performed when indicated by standardized criteria for disc damage or if intraocular pressure (IOP) was 22 mmHg or more.

MAIN OUTCOME MEASURES

An occludable angle was defined as pigmented posterior trabecular meshwork not visible by gonioscopy in three quarters or more of the angle circumference. Manifest primary angle-closure glaucoma (PACG) was defined as IOP of 22 mmHg or more or glaucomatous optic disc damage with visual field loss in the presence of an occludable angle. An IOP of 22 mmHg or more or glaucomatous optic disc damage in the presence of an occludable angle secondary to an obvious cause was defined as secondary ACG.

RESULTS

Manifest PACG and occludable angles without ACG were present in 12 and 24 participants, respectively, with age- and gender-adjusted prevalence (95% confidence interval [CI]) of 0.71% (0.34%-1.31%) and 1.41% (0.73%-2.09%) in participants 30 years of age or older, and 1.08% (0.36%-1.80%) and 2.21% (1.15%-3.27%) in participants 40 years of age or older, respectively. With multivariate analysis, the prevalence of these two conditions considered together increased significantly with age (P < 0.001); although not statistically significant, these were more common in females (odds ratio 1.70; 95% CI, 0.82-3.54) and in those belonging to lower socioeconomic strata as compared with middle and upper strata (odds ratio, 1.82; 95% CI, 0.88-3.74). The odds of manifest PACG were higher in the presence of hyperopia of more than 2 diopters ([D]; odds ratio, 3.69; 95% CI, 0.89-15.2). Only four of 12 participants (33.3%) with manifest PACG had been previously diagnosed, and one of 12 (8.3%) had peripheral iridotomy performed previously. Manifest PACG had caused blindness in one or both eyes in five of these 12 participants (41.7%); best-corrected distance visual acuity less than 20/400 in one or both eyes in four patients, and acuity less than 20/200 in one eye in another patient. Most (83.3%) of those with manifest PACG could be classified as having chronic form of the disease. We may have underestimated manifest PACG because visual fields were per- formed only on those with clinical suspicion of optic disc damage. Secondary ACG was present in two participants.

CONCLUSIONS

The prevalence of PACG in this urban population in southern India is close to that reported recently in a Mongolian population. A large proportion of the PACG in this population was undiagnosed and untreated. Because visual loss resulting from PACG is potentially preventable if peripheral iridotomy or iridectomy is performed in the early stage, strategies for early detection of PACG could reduce the high risk of blindness resulting from PACG seen in this urban population in India.

Open-angle glaucoma in an urban population in southern India: the Andhra Pradesh eye disease study

OBJECTIVE

To assess the prevalence and features of open-angle glaucoma in an urban population in southern India.

DESIGN

A population-based cross-sectional study.

PARTICIPANTS

A total of 2522 persons (85.4% of those eligible) of all ages, including 1399 persons 30 years of age or older, from 24 clusters representative of the population of Hyderabad city.

TESTING

The participants underwent an interview and detailed eye examination that included logarithm of minimum angle of resolution visual acuity, refraction, slit-lamp biomicroscopy, applanation tonometry, gonioscopy, dilatation, cataract grading, and stereoscopic fundus evaluation. Automated Humphrey threshold 24-2 visual fields (Humphrey Instruments Inc., San Leandro, CA) and optic disc photography were performed when indicated by standardized criteria for disc damage or if intraocular pressure (IOP) was 22 mmHg or more.

MAIN OUTCOME MEASURES

Definite primary open-angle glaucoma (POAG) was defined as obvious glaucomatous optic disc damage and visual field loss in the presence of an open-angle, and suspected POAG was defined as suspected glaucomatous optic disc damage without definite visual field loss. Ocular hypertension (OHT) was defined as IOP of 22 mmHg or more without glaucomatous optic disc damage or visual field loss in the presence of an open-angle. Glaucomatous optic disc damage or IOP of 22 mmHg or more secondary to an obvious cause and with an open-angle was defined as secondary open-angle glaucoma.

RESULTS

Definite POAG, suspected POAG, and OHT were present in 27, 14, and 7 participants, respectively, with age- and gender-adjusted prevalence (95% confidence interval) of 1.62% (0.77%-2.48%), 0.79% (0.39%-1.41%), and 0.32% (0.10%-0.78%) in those 30 years of age or older, and 2.56% (1.22%-3.91%), 1.11% (0.43%-1.78%), and 0.42% (0.11%-1.12%) in those 40 years of age or older, respectively. The prevalence of POAG increased significantly with age using multivariate analysis (P < 0.001). Only two of 27 participants (7.4%) with definite POAG had been previously diagnosed and treated, and 66.7% of the previously undiagnosed had IOP less than 22 mmHg. Fourteen of 27 participants (51.9%) with definite POAG had severe glaucomatous damage based on optic disc and visual field criteria, of which five participants (18.5%) had at least one blind eye as a result of POAG (all with best-corrected distance visual acuity less than 20/400 or central visual field less than 10 degrees); the other 13 participants (48.1%) had moderate glaucomatous damage. Because visual fields and optic disc photography were not performed on all participants, the prevalence of POAG may have been underestimated. Secondary open-angle glaucoma was present in one participant as a result of angle recession.

CONCLUSIONS

The prevalence of open-angle glaucoma in this urban population in southern India is at least as much as that reported recently from white populations in developed countries. However, the vast majority of persons with glaucoma were undiagnosed in this population, and a large proportion of those having definite POAG already had severe glaucomatous damage.

Population based assessment of uveitis in an urban population in southern India

AIM

To assess the prevalence of active and inactive uveitis unrelated to previous surgery or trauma in an urban population in southern India.

METHODS

As part of the Andhra Pradesh Eye Disease Study, 2522 subjects (85.4% of those eligible), a sample representative of the population of Hyderabad city in southern India, underwent interview and detailed dilated eye examination. Presence of sequelae of uveitis without current active inflammation was defined as inactive uveitis.

RESULTS

Unequivocal evidence of active or inactive uveitis unrelated to previous surgery or trauma was present in 21 subjects, an age-sex adjusted prevalence of 0.73% (95% confidence interval (CI) 0.44-1.14%). Active uveitis was present in eight subjects, an age-sex adjusted prevalence of 0.37% (95% CI 0. 19-0.70), of which 0.06% was anterior, 0.25% intermediate, and 0.06% posterior. The 0.36% (95% CI 0.17-0.68%) prevalence of inactive uveitis included macular chorioretinitis scars (0.26%), anterior (0. 07%) and previous vasculitis involving the whole eye (0.03%). The prevalence of visual impairment due to uveitis of less than 6/18 in at least one eye was 0.27%, less than 6/60 in at least one eye was 0. 16%, and less than 6/60 in both eyes was 0.03%.

CONCLUSION

These population based cross sectional data give an estimate of the prevalence of various types of uveitis in this urban population in India. Active or past uveitis that might need treatment at some stage was present in one of every 140 people in this population.

Unilateral visual impairment in an urban population in southern India

This study assessed the prevalence and causes of unilateral visual impairment in the urban population of Hyderabad city as part of the Andhra Pradesh Eye Disease Study. Stratified, random, cluster, systematic sampling was used to select 2,954 subjects from 24 clusters representative of the population of Hyderabad. Eligible subjects underwent detailed eye examination including logMAR visual acuity, refraction, slitlamp biomicroscopy, applanation tonometry, gonioscopy, dilatation, cataract grading, and stereoscopic evaluation of fundus. Automated threshold visual fields and slitlamp and fundus photography were done when indicated by standardised criteria. Unilateral visual impairment was defined as presenting distance visual acuity < 6/18 in the worse eye and > or = 6/12 in the better eye, which was further divided into unilateral blindness (visual acuity < 6/60 in the worse eye) and unilateral moderate visual impairment (visual acuity < 6/18-6/60 in the worse eye). A total of 2,522 subjects (85.4% of eligible), including 1,399 > or = 30 years old, participated in the study. In addition to the 1% blindness and 7.2% moderate visual impairment (based on bilateral visual impairment criteria) reported earlier in this sample, 139 subjects had unilateral visual impairment, an age-gender-adjusted prevalence of 3.8% (95% confidence interval 2.7-4.9%). The major causes of this visual impairment 39.9% were refractive error (42.9%), cataract (14.4%), corneal disease (11.5%), and retinal disease (11.2%). Of this unilateral visual impairment was blindness. The major causes of unilateral blindness were corneal disease (23.2%), cataract (22.5%), retinal disease (18%), and optic atrophy (12.9%). On the other hand, the predominant cause of unilateral moderate visual impairment was refractive error (67%) followed by cataract (9%). Of the total unilateral visual impairment, 34.3% was present in those < 30 years old and 36.2% in those 30-49 years old. Unilateral visual impairment afflicts approximately 1 in 25 persons in this urban population. A large proportion of this unilateral visual impairment is present in younger age groups. The causes of unilateral visual impairment, like those of bilateral visual impairment in this population, are varied, suggesting therefore, that in addition to the current focus of eye care in India predominantly on cataract, other causes of visual impairment need to be addressed as well.

Adaptation of WHOQOL as health-related quality of life instrument to develop a vision-specific instrument

The WHOQOL instrument was adapted as a health-related QOL instrument for a population-based epidemiologic study of eye diseases in southern India, the Andhra Pradesh Eye Disease Study (APEDS). A follow-up question was added to each item in WHOQOL to determine whether the decrease in QOL was due to any health reasons including eye-related reasons. Modifications in WHOQOL and translation in local language were done through the use of the focus groups including health professionals and people not related to health care. The modified instrument has 28 items across 6 domains of the WHOQOL and was translated into the local language, Telugu, using the pragmatic approach. It takes 10-20 minutes to be administered by a trained interviewer. Reliability was within acceptable range. This health-related QOL instrument is being used in the population-based study APEDS to develop a vision-specific QOL instrument which could potentially be used to assess the impact of visual impairment on QOL across different cultures and for use in evaluating eye-care interventions. This health-related QOL instrument could also be used to develop other disease-specific instruments as it allows assessment of the extent to which various aspects of QOL are affected by a variety of health problems.

Utilisation of eyecare services in an urban population in southern India: the Andhra Pradesh eye disease study

AIM

To assess utilisation of eyecare services by people with visual impairment <6/18 or equivalent visual field loss in the better eye in the urban population of Hyderabad in southern India.

METHODS

2522 subjects of all ages, representative of the population of Hyderabad city, underwent a detailed interview and dilated examination as part of the population based Andhra Pradesh eye disease study. Subjects more than 15 years of age were interviewed regarding the use of eyecare services.

RESULTS

Of 250 subjects with presenting distance visual acuity <6/18 or equivalent visual field loss in the better eye, information on utilisation of eyecare services was available for 229 (91.6%). Of these 229 subjects, 44 (19%) had visual acuity <6/60 or equivalent visual field loss in the better eye, and 202 (88.2%) had noticed decrease in vision over the past 5 years. Multivariate analysis showed that this decrease in vision was noticed significantly less by subjects with refractive error as the cause of visual impairment (odds ratio 0.34, 95% confidence interval 0.12-0.93). Of the 229 subjects who were visually impaired, 108 (59%) did not seek treatment. Multivariate analysis revealed that the odds for seeking treatment were significantly lower for Hindus than Muslims (odds ratio 0.53, 95% confidence interval 0.28-0.98). The reasons for not seeking treatment could be classified as personal (49.5%), economic (30.8%), and social (19.6%).

CONCLUSION

A large proportion of subjects with visual impairment in this urban population in India did not seek treatment even after noticing decrease in vision. Projecting these data to the 155 million urban population >15 years of age in India, there may be 4.9 million (95% confidence interval 4.3-5.5 million) people in urban India who are not seeking treatment for their visual impairment even after noticing decrease in vision. These data suggest that efforts have to be made to better understand the reasons for this phenomenon so that optimal utilisation of the available eyecare services in urban India can be planned.

Refractive errors in an urban population in Southern India: the Andhra Pradesh Eye Disease Study

PURPOSE

To assess the prevalence, distribution, and demographic associations of refractive error in an urban population in southern India.

METHODS

Two thousand five hundred twenty-two subjects of all ages, representative of the Hyderabad population, were examined in the population-based Andhra Pradesh Eye Disease Study. Objective and subjective refraction was attempted on subjects >15 years of age with presenting distance and/or near visual acuity worse than 20/20 in either eye. Refraction under cycloplegia was attempted on all subjects < or =15 years of age. Spherical equivalent >0.50 D in the worse eye was considered as refractive error. Data on objective refraction under cycloplegia were analyzed for subjects < or =15 years and on subjective refraction were analyzed for subjects >15 years of age.

RESULTS

Data on refractive error were available for 2,321 (92.0%) subjects. In subjects < or =15 years of age, age-gender-adjusted prevalence of myopia was 4.44% (95% confidence interval [CI], 2.14%-6.75%), which was higher in those 10 to 15 years of age (odds ratio, 2.75; 95% CI, 1.25-6.02), of hyperopia 59.37% (95% CI, 44.65%-74.09%), and of astigmatism 6.93% (95% CI, 4.90%-8.97%). In subjects >15 years of age, age-gender-adjusted prevalence of myopia was 19.39% (95% CI, 16.54%-22.24%), of hyperopia 9.83% (95% CI, 6.21%-13.45%), and of astigmatism 12.94% (95% CI, 10.80%-15.07%). With multivariate analysis, myopia was significantly higher in subjects with Lens Opacity Classification System HI nuclear cataract grade > or =3.5 (odds ratio, 9.10; 95% CI, 5.15-16.09), and in subjects with education of class 11 or higher (odds ratio, 1.80; 95% CI, 1.18-2.74); hyperopia was significantly higher in subjects > or =30 years of age compared with those 16 to 29 years of age (odds ratio, 37.26; 95% CI, 11.84-117.19), in females (odds ratio, 1.86; 95% CI, 1.33-2.61), and in subjects belonging to middle and upper socioeconomic strata (odds ratio, 2.10; 95% CI, 1.09-4.03); and astigmatism was significantly higher in subjects > or =40 years of age (odds ratio, 3.00; 95% CI, 2.23- 4.03) and in those with education of college level or higher (odds ratio, 1.73; 95% CI, 1.07-2.81).

CONCLUSIONS

These population-based data on distribution and demographic associations of refractive error could enable planning of eye-care services to reduce visual impairment caused by refractive error. If these data are extrapolated to the 255 million urban population of India, among those >15 years of age an estimated 30 million people would have myopia, 15.2 million hyperopia, and 4.1 million astigmatism not concurrent with myopia or hyperopia; in addition, based on refraction under cycloplegia, 4.4 million children would have myopia and 2.5 million astigmatism not concurrent with myopia or hyperopia.

Population based assessment of diabetic retinopathy in an urban population in southern India

AIM

To assess the prevalence of diabetic retinopathy and the visual impairment caused by it in an urban population in southern India in order to determine its public health significance.

METHODS

2522 subjects (85.4% of those eligible), a representative sample of the population of Hyderabad city in southern India, underwent interview and detailed dilated eye examination during 1996-7 as part of the Andhra Pradesh Eye Disease Study.

RESULTS

124 subjects, all >/=30 years old, reported that they had diabetes, an age-sex adjusted prevalence of 7.82% (95% confidence interval (CI) 5.76-9.88%) in this age group. Diabetes was diagnosed at age >/=30 years in all but two subjects. The duration since diagnosis of diabetes was <10 years in 75.6% and >/=15 years in 6.7%. Diabetic retinopathy was present in 28 subjects, 1.78% (95% CI 1.09-2.48%) of those >/=30 years old. Most of the diabetic retinopathy was of the mild (50%) or moderate (39.3%) non-proliferative type; one subject (3.6%) had proliferative retinopathy. Multiple logistic regression revealed that the odds of having diabetic retinopathy were significantly higher in those >/=50 years than in those 30-49 years old (odds ratio 7.78, 95% CI 2.92-20. 73). Three subjects had visual impairment between 6/12 and 6/38 in either eye due to diabetic retinopathy, 0.19% (95% CI 0-0.41%) of those >/=30 years old.

CONCLUSION

Visual impairment due to diabetic retinopathy was relatively uncommon in this urban Indian population in 1996-7. However, this could change in the near future with an increase in duration of diabetes because of the anticipated aging of India's population and the recent suggestion of increase in diabetes prevalence in urban India, and therefore should be monitored.

Awareness of eye donation in an urban population in India

PURPOSE

Awareness of eye donation and willingness to pledge eyes for donation was assessed in the urban population of Hyderabad, India, where corneal blindness is a significant problem.

METHODS

A total of 2522 subjects of all ages, representative of the Hyderabad population, participated in the Andhra Pradesh Eye Disease Study. Subjects >15 years old were interviewed regarding awareness of eye donation and willingness to pledge eyes for donation.

RESULTS

Age-gender-adjusted prevalence of awareness of eye donation was 73.8% (95% CI: 66.5-81.0%) but only 1.9% (95% CI: 0.16-3.66%) had pledged eyes. With multivariate analysis, significantly less awareness of eye donation was found in illiterate subjects (OR 0.1; 95% CI: 0.1-0.14), subjects > or =70 years old (OR 0.3; 95% CI: 0.2-0.6), subjects of lower socio-economic status (OR 0.4; 95% CI: 0.3-0.6), females (OR 0.6; 95% CI: 0.5-0.8) and Muslims (OR 0.7; 95% CI: 0.6-0.9). Media was the major source of information about eye donation. Of those aware of eye donation, 44.9% were willing to pledge eyes. Willingness to pledge eyes for donation was significantly lower in Muslims (OR 0.18; 95% CI: 0.13-0.24) than in Hindus and in subjects > or =60years old (OR 0.3; 95% CI: 0.2-0.5).

CONCLUSIONS

These data show that although only a few had pledged eyes there is enough potential in this population for obtaining many more corneas for transplantation. The information about distribution and demographic associations of awareness and willingness for eye donation could help in developing strategies to increase procurement of corneas for dealing with corneal blindness.

Population-based assessment of the outcome of cataract surgery in an urban population in southern India

PURPOSE

To assess the outcome of cataract surgery in an urban population in southern India.

METHODS

As part of a population-based cross-sectional epidemiologic study, the Andhra Pradesh Eye Disease Study, 2,522 people of all ages, including 1,399 individuals 30 years of age or older, from 24 clusters representative of the population of Hyderabad in southern India underwent a detailed interview and ocular evaluation including logarithm of minimal angle of resolution (logMAR) visual acuity, refraction, slit-lamp biomicroscopy, applanation tonometry, gonioscopy, dilation, cataract grading, aphakia/pseudophakia status, and stereoscopic fundus evaluation. Automated threshold visual fields and slit-lamp and fundus photography were performed when indicated by standardized criteria. Very poor outcome in an eye that had undergone cataract surgery was defined as presenting distance visual acuity worse than 20/200, and poor outcome was defined as visual acuity worse than 20/60 to 20/200.

RESULTS

In subjects 50 years of age or older, after adjustment for age and sex distribution, the rate of having had cataract surgery in one or both eyes was 14.6% (95% confidence interval [CI], 11.4% to 17.8%). Of 131 eyes (91 subjects) that had undergone cataract surgery, 28 (21.4%; 95% CI, 14.4% to 28.4%) had very poor outcome and another 40 (30.5%; 95% CI, 22.6% to 38.4%) had poor outcome. The very poor outcome in 20 (71.4%) of 28 eyes and poor outcome in 23 (57.5%) of 40 eyes could be attributed to surgery-related causes or inadequate refractive correction. With multivariate analysis, very poor outcome as a result of surgery-related causes or inadequate refractive correction was more likely to be associated with intracapsular cataract extraction than with extracapsular cataract extraction (odds ratio, 9.34; 95% CI, 2.49 to 35.06) in subjects belonging to the lowest socioeconomic status (odds ratio, 4.92; 95% CI, 1.16 to 20.93) and with date of surgery 3 or fewer years before the survey than with more than 3 years (odds ratio, 4.52; 95% CI, 1.33 to 15.39). Also, very poor or poor outcome as a result of surgery-related causes or inadequate refractive correction was associated with women (odds ratio, 2.55; 95% CI, 1.06 to 6.16).

CONCLUSIONS

The very high rate of very poor and poor visual outcome, predominantly as a result of surgery-related causes and inadequate refractive correction, in this urban population of India suggests that more attention is needed to improve the visual outcome of cataract surgery. In order to deal with cataract-related visual impairment in India, as much emphasis on surgical quality, refractive correction, and follow-up care is necessary as on the number of surgeries.

Burden of moderate visual impairment in an urban population in southern India

OBJECTIVE

To assess the prevalence and causes of moderate visual impairment in an urban population in southern India.

DESIGN

Population-based, cross-sectional study.

PARTICIPANTS

A total of 2522 (85.4% of the eligible) persons of all ages, including 1399 persons 30 years of age or older, from 24 clusters representative of the population of Hyderabad city.

TESTING

The eligible subjects underwent a detailed ocular evaluation, including logarithm of the minimum angle of resolution (logMAR) visual acuity, refraction, slit-lamp biomicroscopy, applanation tonometry, gonioscopy, cataract grading, and stereoscopic dilated fundus evaluation. Automated threshold visual fields and slit-lamp and fundus photography were done when indicated by standardized criteria.

MAIN OUTCOME MEASURE

Moderate visual impairment was defined as presenting distance visual acuity less than 20/40 to 20/200 or visual field loss by predefined standardized conservative criteria in the better eye.

RESULTS

In addition to the 1% prevalence of blindness in this sample reported earlier, moderate visual impairment was present in 303 subjects, an age-gender-adjusted prevalence of 7.2% (95% confidence interval [CI], 4.5%-9.9%; design effect, 2.7). The major cause of moderate visual impairment was refractive error (59.4%, 95% CI, 52.3%-66.5%) followed by cataract (25.3%, 95% CI, 19%-31.6%). Multivariate analysis showed that the prevalence of moderate visual impairment was significantly higher in those 40 years of age or older (odds ratio, 10.9; 95% CI, 8-15) and females (odds ratio, 1.89; 95% CI, 1.41-2.53) and lower in those belonging to the highest socioeconomic status (odds ratio, 0.27; 95% CI, 0.14-0.51). However, because of the pyramidal age distribution of the population, 38.1% of the total moderate visual impairment was present in those younger than 40 years of age. The proportion of moderate visual impairment caused by refractive error was higher in the younger than in the older age groups (P < 0.0001).

CONCLUSIONS

Projecting the results to the 26.5% urban population of India, there would be 18.4 million (95% CI, 11.5-25.2 million) persons with moderate visual impairment in urban India alone. Refractive error was the major cause of moderate visual impairment in the population studied. The absolute proportion of moderate visual impairment in those younger than 40 years of age was considerable. The eyecare policy of India, apart from dealing with blindness, should address the issue of the relatively easily treatable uncorrected refractive error as the cause of moderate visual impairment in an estimated 10.9 million persons in urban India.

Developing a model to reduce blindness in India: The International Centre for Advancement of Rural Eye Care

With the continuing high magnitude of blindness in India, fresh approaches are needed to effectively deal with this burden on society. The International Centre for Advancement of Rural Eye Care (ICARE) has been established at the L.V. Prasad Eye Institute in Hyderabad to develop such an approach. This paper describes how ICARE functions to meet its objective. The three major functions of ICARE are design and implementation of rural eye-care centres, human resource development for eye care, and community eye-health planning. ICARE works with existing eye-care centres, as well as those being planned, in underserved areas of India and other parts of the developing world. The approach being developed by ICARE, along with its partners, to reduce blindness is that of comprehensive eye care with due emphasis on preventive, curative and rehabilitative aspects. This approach involves the community in which blindness is sought to be reduced by understanding how the people perceive eye health and the barriers to eye care, thereby enabling development of strategies to prevent blindness. Emphasis is placed on providing good-quality eye care with attention to reasonable infrastructure and equipment, developing a resource of adequately trained eye-care professionals of all cadres, developing a professional environment satisfactory for patients as well as eye-care providers, and the concept of good management and financial self-sustainability. Community-based rehabilitation of those with incurable blindness is also part of this approach. ICARE plans to work intensively with its partners and develop these concepts further, thereby effectively bringing into practice the concept of comprehensive eye care for the community in underserved parts of India, and later in other parts of the developing world. In addition, ICARE is involved in assessing the current situation regarding the various aspects of blindness through well-designed epidemiologic studies, and projecting the eye-care needs for the future with the help of reliable information. With balanced attention to infrastructure, manpower, financial self-sustenance, and future planning, ICARE intends to develop a practical model to effectively reduce blindness in India on a long-term basis.

Is current eye-care-policy focus almost exclusively on cataract adequate to deal with blindness in India?

BACKGROUND

India's National Programme for Control of Blindness focuses almost exclusively on cataract, based on a national survey done in the 1980s which reported that cataract caused 80% of the blindness in India. No current population-based data on the causes of blindness in India are available. We assessed the rate and causes of blindness in an urban population in southern India.

METHODS

We selected 2954 participants by stratified, random, cluster, systematic sampling from Hyderabad city. Eligible participants were interviewed and given a detailed ocular assessment, including visual acuity, refraction, slitlamp biomicroscopy, applanation intraocular pressure, gonioscopy, dilatation, grading of cataract, stereoscopic fundus assessment, and automated-threshold visual fields.

FINDINGS

2522 participants, including 1399 aged 30 years or more, were assessed. 49 participants (all aged > or =30 years) were blind (presenting distance visual acuity <6/60 or central visual field <200 in the better eye). The rate of blindness among those aged 30 years or more, adjusted for age and sex, was 3.08% ([95% CI 1.95-4.21]). Causes included cataract (29.7%), retinal disease (17.1%), corneal disease (15.4%), refractive error (12.5%), glaucoma (12.1%), and optic atrophy (11.0%). 15.7% of the blindness caused by visual-field constriction would have been missed without visual-field examination. Also without visual-field and detailed dilated-fundus assessments, blindness attributed to cataract would have been overestimated by up to 75.8%. If the use of cataract surgery in this urban population was half that found in this study, which simulates the situation in rural India, cataract would have caused 51.8% (39.4-64.2) of blindness, significantly less than the 80% accepted by current policy.

INTERPRETATION

Much of the blindness in this Indian population was due to non-cataract causes. The previous national survey did not include detailed dilated-fundus assessment and visual-field examination which could have led to overestimation of cataract as a cause of blindness in India. Policy-makers in India should encourage well-designed population-based epidemiological studies from which to develop a comprehensive long-term policy on blindness in addition to dealing with cataract.

Design of a population-based study of visual impairment in India: The Andhra Pradesh Eye Disease Study

Reliable population-based epidemiologic data regarding vision and ocular morbidity, as well as those about the perceptions of people regarding visual impairment and eye care, are lacking for the most part in the developing world including India. These data are the basis on which effective eye care services can be developed. To meet this need we designed the Andhra Pradesh Eye Disease Study, a population-based epidemiology study of 10,000 people in the Indian state of Andhra Pradesh. The design of this study is described in this paper. Various options for the sample size, study areas, sampling procedure, and recruitment of subjects were considered. A sample size of 10,000 people, 5,000 each in the < or = 30 and > 30 years age groups, was determined to obtain reasonable confidence in estimating the prevalence of diseases and odds ratios for risk factors of interest. A multistage sampling strategy was chosen for the study which was assumed to give a design effect of 1.5 for the estimates. One urban area, Hyderabad, and three rural areas, West Godavari, Adilabad and Mahbubnagar districts, were selected in Andhra Pradesh. Interview instruments were developed to obtain detailed information about demographic data, diet, ocular and systemic history, risk factors for eye diseases, visual function, quality of life, barriers to eye care, and knowledge about eye diseases. A detailed examination procedure was devised to obtain a broad range of normative and abnormal data related to eyes and vision. A protocol was developed for doing automated visual fields, slitlamp and fundus photography. Computer databases were made in FoxPro for data entry and subsequent analysis with SPSS. Pilot studies were done to test the instruments, procedures, and logistics of the study in urban and rural areas. Information from the Andhra Pradesh Eye Disease Study is expected to help in planning and implementation of effective long-term preventive, curative, and rehabilitative eye care services in Andhra Pradesh.