Visual impairment a significant, growing problem in India

More than 80 million people in India have moderate visual impairment.

ByLou Koury

HYDERABAD, India — In addition to blindness, there is a significant and growing burden of moderate visual impairment in India.

“Extrapolation of our data show that in the year 2000 there were 82 million people with moderate visual impairment in the population of India. This number is likely to be 139 million by the year 2020 if the current trend continues,” Rakhi Dandona, PhD, reported in the British Journal of Ophthalmology.

Dr. Dandona and colleagues at the Centre for Social Services, Administrative Staff College of India assessed the prevalence and demographics of moderate visual impairment in the population of the southern Indian state of Andhra Pradesh.

Population-based investigation

The population-based Andhra Pradesh Eye Disease Study (APEDS) was conducted in one urban and three rural populations. The state had a population of 75.7 million in 2001, 7.4% of the total population of India. The blindness data from APEDS, 1.84% of the population, have been previously reported.

For this investigation, researchers sampled 11,786 people of all ages from 94 clusters using a stratified, random-cluster, systematic sampling strategy. They were invited for an interview and given a detailed eye examination. Of this sample, 10,293 people participated. The eye examination included measurement of presenting and best corrected distance and near visual acuities under standardized conditions, Dr. Dandona and colleagues reported. Researchers also performed external eye exams and slit-lamp, IOP, posterior segment and automated visual field tests.

Of the included patients, 75.5% were from the three rural areas and 52.8% were women.

“Moderate visual impairment was defined as presenting distance visual acuity less than 6/18 to 6/60 or equivalent visual field loss. In addition to the previously reported blindness prevalence, 1,237 people had moderate visual impairment,” Dr. Dandona said.

Prevalence of visual impairment

After adjusting for age, sex and urban-rural distribution, the prevalence of moderate visual impairment in this study was 8.1% (95% CI, 6.9 to 9.3). Dr. Dandona and colleagues reported that visual field loss was responsible for 0.96% of the impairment.

“If only the three rural areas of APEDS were considered, the prevalence of moderate visual impairment was 8.9%,” Dr. Dandona noted.

The leading cause of moderate visual impairment was refractive error at 45.8%, followed by cataract at 39.9%, they found.

“Prevalence of moderate visual impairment due to refractive error, cataract, amblyopia and corneal diseases was higher in rural areas vs. the urban area. Causes such as retinal diseases, optic atrophy and glaucoma were similar,” Dr. Dandona said.

Refractive error was the most frequent cause of moderate visual impairment in people younger than 60 years of age, and cataract was the most common cause in those older than 60 years.

Demographics of impaired vision

After researchers excluded the patients who were reported as blind (distance visual acuity less than 60/60 or central visual field less than 20° in the better eye), the population considered for demographic association was 10,018. About 75% of these were from the three rural areas, a little more than half were older than 30 years and 52.7% were women.

“The odds of having moderate visual impairment increased with increasing age and with decreasing socioeconomic status,” Dr. Dandona reported.

Women vs. men (OR 1.47) and those living in rural areas (OR 2.12) vs. urbanites also had significantly higher odds of having moderate visual impairment.

If these data from APEDS were extrapolated to the estimated population of Andhra Pradesh in 2000, 6.1 million people would have moderate visual impairment, the investigators wrote. Extrapolating the data further would mean that 82.1 million people in the entire country would have moderate visual impairment.

“If the current age-sex specific rates of moderate visual impairment continue, the prevalence in the years 2010 and 2020 would be 9.2% and 10.7%,” Dr. Dandona said.

India’s eye care needs

“This impending large burden of moderate visual impairment, the majority of which is due to the relatively easily treatable conditions of refractive error and cataract, would have to be taken into account while estimating eye care needs in India,” Dr. Dandona and colleagues concluded.

They emphasized, therefore, that the sizable blindness problem is not the only concern.

“Knowledge of the demographic associations for moderate visual impairment can help in identifying groups within the population who need particular attention in strategies to reduce this burden,” the researchers said. “Specific strategies targeting the elderly population, women, people with low socioeconomic status and those living in rural areas would have to be implemented in the long term to reduce moderate visual impairment.”

For Your Information:

Rakhi Dandona, PhD, can be reached at Administrative Staff College of India, Bella Vista, Raj Bhavan Rd., Hyderabad-500082, India; +91-40-331-0952; fax: +91-40-331-2954; e-mail: rakhi@asci.org.in.

Reference:

Dandona R, Dandona L, et al. Moderate visual impairment in India: the Andhra Pradesh Eye Disease Study. Br J Ophthalmol. 2002;86:373-377.