National Blindness and Visual Impairment Survey

About National Blindness and Visual Impairment Survey 2015-2019

The National Blindness and Visual Impairment Survey 2015-2019 was conducted in order to provide the evidence about the present status of blindness and visual impairment in India. The survey was planned by the Ministry of Health and Family Welfare, Government of India. Dr Rajendra Prasad Centre for Ophthalmic Sciences, AIIMS, New Delhi was responsible for planning and executing the field work, monitoring, analysis and report writing of the survey. The survey was conducted in partnership with various reputed Eye Health Institutes of the country.

Objectives

• To determine the prevalence of blindness and visual impairment (including avoidable blindness)
• To identify the major causes of blindness and visual impairment (including avoidable blindness) in India
• To estimate the cataract surgical coverage in India in 50+ population
• To ascertain the visual outcomes after cataract surgery in 50+ population
• To ascertain barriers for uptake of cataract surgery in 50+ population

Methodology

• The survey in population aged ≥ 50 years was done using the Rapid Assessment of Avoidable Blindness (RAAB-6) methodology developed at the International Centre for Eye Health (ICEH), London and recommended by the WHO.
• A total of 31 districts were randomly selected among the districts in India for the survey and a sample size of 3,000 was calculated to represent each district. 
• A direct age and sex standardization of each district’s survey data to that district’s population age-sex structure was done as per the 2011 census, to estimate district-wise prevalence.
• Finally, in order to account for variation in population size of various districts, each district was allotted a sampling weight based on the district’s
  total population aged ≥ 50 years. 
• For 0-49 years population survey, sample size was estimated as 18,000 for the country. One district was chosen from each of the 6 zones of the country to ensure the heterogeneity of the sample population.
• Results of both these surveys were used to estimate the prevalence of blindness, SVI, MVI, EVI, MSVI and VI across all age groups in India. Based on the prevalence of blindness and VI, the total number of blind and visually impaired persons were extrapolated for the country for the year 2017.

Results

• Prevalence of blindness & visual impairment - The estimated prevalence of blindness was 1.99%, SVI 1.96%, MVI 9.81%, EVI 12.92%, MSVI 11.77% and VI 13.76%. Prevalence of functional low vision was 1.03% and that of blindness<3/60 (using pinhole) was 1.75%. The prevalence of blindness and visual impairment was lowest in Thrissur district (Kerala) and in Thoubal district (Manipur) respectively. Bijnor district (Uttar Pradesh) had the highest prevalence of both blindness and visual impairment. 
• Maximum prevalence of blindness was seen in 80+ age group (11.6%), followed by 70-79 age group (4.1%), 60-69 age group (1.6%) and 50-59 age group (0.5%)
• Blindness was higher among illiterates (3.23%) compared to literate population. It was only 0.43% among 10th pass and above.
• Causes of blindness and visual impairment ( ≥ 50 years)
  • Cataract was the principal cause of blindness (66.2%), severe visual impairment (80.7%), and moderate visual impairment (70.2%)
  • The other important causes of blindness were corneal opacity (7.4%), cataract surgical complications (7.2%), posterior segment disorders excluding DR and ARMD (5.9%) and glaucoma (5.5%).
  • Principal causes of severe visual impairment other than cataract were cataract surgical complications (8.3%) and other posterior segment diseases excluding DR and ARMD (3.4%).
  • For early visual impairment, the most important cause was refractive error (70.6%). 
• Most of the blindness and visual impairment were due to avoidable causes (92.9% and 96.2% respectively). Among avoidable causes, treatable causes of blindness and VI were 68.1% and 85.7% respectively. 
• Barriers in accessing cataract surgical services in population aged ≥ 50 years - Among those people who were identified to have pinhole visual acuity <3/60 and having bilateral cataract, most commonly reported barriers were local reasons (25.5%, including no one to accompany, seasonal preferences, personal reasons). Other important barriers were financial constraints (22.1%), need for surgery not felt (18.4%) and fear of surgery (16.1%). Among males, the most important barriers were financial constraints (31.0%) and local reasons (21.5%). Among females, local reasons (23.1%) and financial constraints (21.2%) were most important barriers.
• The prevalence of visual impairment was 4.43 per thousand and blindness was 0.52 per thousand in the 0-49 year age group.
• Causes of blindness and visual impairment in population aged 0-49 years - Majority cases of blindness were due to non-trachomatous corneal blindness (37.5%). Most important causes of VI were refractive error (29.6%), untreated cataract (25.4%), all globe/ CNS abnormality (15.5%), and non-trachomatous corneal opacity (14.1%).
• Prevalence of blindness and visual impairment in overall population - Estimated prevalence in overall population of blindness was 0.36%, severe visual impairment was 0.35%, moderate visual impairment was 1.84%, early visual impairment was 2.92%. Estimated moderate severe visual impairment in overall population was 2.19% and that of visual impairment was 2.55%. Estimated prevalence of pinhole blindness in overall population of India was 0.32%.
• Trends of blindness and visual impairment over the years in population aged ≥ 50 years
  • Over the years, the prevalence of blindness among ≥ 50 population has reduced considerably. Blindness, as defined by presenting visual acuity <3/60 in better eye, has reduced from 5.3% in 2001 to 3.60% in 2007 to 1.99% in current survey. Visual impairment has reduced from 32.3% in 2001 to 24.8% in 2007 to 13.73% in current survey in ≥ 50 population.
  • Cataract continue to be the major cause of blindness and responsible for 66.2% of blindness. Refractive error was the most important cause of visual impairment and second important cause of blindness in 2001 but the current survey showed that refractive error is not an important cause of blindness. Corneal blindness emerged as the second important cause of blindness. Beside this, the proportion of blindness due to complications of cataract surgery have also increased.
• Reduction in blindness, moderate severe visual impairment and visual impairment from 2010 estimates
  • The WHO Global Action Plan for Universal Eye Health 2014-2019 targets a reduction in the prevalence of visual impairment by 25% by 2019 from the baseline level of 2010. The WHO estimated a prevalence of blindness, MSVI and VI as 0.68%, 4.62% and 5.30% respectively in India for the year 2010.
  • The  current survey shows a reduction of 47.1% in blindness, 52.6% in MSVI and 51.9% in VI compared to the baseline levels. This shows that the target of 25% reduction in visual impairment have been achieved successfully by India.

To access the report, click here. 

Source : National Program for Control of Blindness and Visual Impairment (NPCB&VI), DGHS