Cataract is a public health problem in many developing countries, including India. Traditionally, the cataract intervention programme is evaluated by the number of cataract operations performed per year. In India this has increased from 1.2 million in 1989 to 2.7 million operations in 1996.1 However impressive this increase may be, the figure does not indicate the extent to which the problem of cataract blindness has been reduced.

Two indicators are used to measure impact. First, it can be measured by a change in prevalence of cataract blindness, obtained through community based surveys. Since blindness surveys are costly and lengthy exercises, these are not conducted regularly. In India, a national study was done in the period 1971–74 and a National Survey on Blindness in 1986–89. The variation in prevalence of blindness and visual impairment due to cataract over this period indicates the impact surgical services have had on the magnitude of the problem.







Advanced cataract, left eye, in Sri Lanka

Photo:Victoria Sheffield

CATARACT SURGICAL COVERAGE: An indicator to measure the impact of cataract intervention programmes.

Aims: To assess the prevalence of vision impairment, blindness, and cataract surgery and to evaluate visual acuity outcomes after cataract surgery in a south Indian population Methods: Cluster sampling was used to randomly select a cross sectional sample of people ≥50 years of age living in the Tirunelveli district of south India Eligible subjects in 28 clusters were enumerated through a door to door household survey Visual acuity measurements and ocular examinations were performed at a selected site within each of the clusters in early 2000 The principal cause of visual impairment was identified for eyes with presenting visual acuity Results: A total of 5795 people in 3986 households were enumerated and 5411 (9337%) were examined The prevalence of presenting and best corrected visual acuity ≥6/18 in both eyes was 594% and 757%, respectively Presenting vision Conclusion: Treatable blindness, particularly that associated with cataract and refractive error, remains a significant problem among older adults in south Indian populations, especially in females, the illiterate, and those living in rural areas Further study is needed to better understand why a significant proportion of the cataract blind are not taking advantage of free of charge eye care services offered by the Aravind Eye Hospital and others in the district While continuing to increase cataract surgical volume to reduce blindness, emphasis must also be placed on improving postoperative visual acuity outcomes

https://bjo.bmj.com/content/bjophthalmol/86/5/505.full.pdf

A population based eye survey of older adults in Tirunelveli district of south India: blindness, cataract surgery, and visual outcomes

Background 
Rapid assessment of avoidable blindness provides valid estimates in a short period of time to assess the magnitude and causes of avoidable blindness. The study determined magnitude and causes of avoidable blindness in India in 2007 among the 50+ population.


Methods and Findings 
Sixteen randomly selected districts where blindness surveys were undertaken 7 to 10 years earlier were identified for a follow up survey. Stratified cluster sampling was used and 25 clusters (20 rural and 5 urban) were randomly picked in each district.. After a random start, 100 individuals aged 50+ were enumerated and examined sequentially in each cluster. All those with presenting vision = 50 years were enumerated, and 94.7% examined. Based on presenting vision,, 4.4% (95% Confidence Interval[CI]: 4.1,4.8) were severely visually impaired (vision<6/60 to 3/60 in the better eye) and 3.6% (95% CI: 3.3,3.9) were blind (vision<3/60 in the better eye). Prevalence of low vision (<6/18 to 6/60 in the better eye) was 16.8% (95% CI: 16.0,17.5). Prevalence of blindness and severe visual impairment (<6/60 in the better eye) was higher among rural residents (8.2%; 95% CI: 7.9,8.6) compared to urban (7.1%; 95% CI: 5.0, 9.2), among females (9.2%; 95% CI: 8.6,9.8) compared to males (6.5%; 95% CI: 6.0,7.1) and people above 70 years (20.6%; 95% CI: 19.1,22.0) compared to people aged 50–54 years (1.3%; 95% CI: 1.1,1.6). Of all blindness, 88.2% was avoidable. of which 81.9% was due to cataract and 7.1% to uncorrected refractive errors/uncorrected aphakia.


Conclusions 
Cataract and refractive errors are major causes of blindness and low vision and control strategies should prioritize them. Most blindness and low vision burden is avoidable.

/pdf/rapid-assessment-of-avoidable-blindness-in-india-etb0quhyrx.pdf

Rapid Assessment of Avoidable Blindness in India

OBJECTIVE: To determine, from the existing literature, cataract surgical coverage rates by sex and the proportion of cataract blindness that could be eliminated if women and men had equal access to cataract surgical services. METHOD: Methodologically sound population-based cataract surveys from developing countries were identified through a literature search. Cataract surgical coverage rates were extracted from the surveys and rates for women were compared to those for men. Peto odds ratios were calculated for each survey and a meta-analysis of the surveys was performed. FINDINGS: From a literature review and meta-analysis of cataract surveys in developing countries, we found that the cataract surgical coverage rate was 1.2-1.7 times higher for males than for females. For females, the odds ratio of having surgery, compared to males, was 0.67 (95% confidence interval (CI): 0.60- 0.74). Despite their lower coverage rate, females accounted for approximately 63% of all cataract cases in the study populations, and if they received surgery at the same rates as males, the prevalence of cataract blindness would be reduced by a median of 12.5% (range 4-21%). CONCLUSION: Closing the gender gap could thus significantly decrease the prevalence of cataract blindness, and gender-sensitive intervention programmes are needed to improve cataract surgical coverage among females.

/pdf/gender-and-use-of-cataract-surgical-services-in-developing-46pvhhy4zk.pdf

Gender and use of cataract surgical services in developing countries

Background: India is a signatory to the World Health Organization resolution on Vision 2020: The right to sight. Efforts of all stakeholders have resulted in increased number of cataract surgeries performed in India, but the impact of these efforts on the elimination of avoidable blindness is unknown. Aims: Projection of performance of cataract surgery over the next 15 years to determine whether India is likely to eliminate cataract blindness by 2020. Materials and Methods: Data from three national level blindness surveys in India over three decades, and projected age-specific population till 2020 from US Census Bureau were used to develop a model to predict the magnitude of cataract blindness and impact of Vision 2020: the right to sight initiatives. Results: Using age-specific data for those aged 50+ years it was observed that prevalence of blindness at different age cohorts (above 50 years) reduced over three decades with a peak in 1989. Projections show that among those aged 50+ years, the quantum of cataract surgery would double (3.38 million in 2001 to 7.63 million in 2020) and cataract surgical rate would increase from 24025/million 50+ in 2001 to 27817/million 50+ in 2020. Though the prevalence of cataract blindness would decrease, the absolute number of cataract blind would increase from 7.75 million in 2001 to 8.25 million in 2020 due to a substantial increase in the population above 50 years in India over this period. Conclusions: Considering existing prevalence and projected incidence of cataract blindness over the period 2001-2020, visual outcomes after cataract surgery and sight restoration rate, elimination of cataract blindness may not be achieved by 2020 in India.

Current status of cataract blindness and Vision 2020: the right to sight initiative in India.

AIM: To identify indicators to monitor and evaluate the cataract intervention programme in India. METHODS: Available data on blindness due to cataract, demography, staffing levels, and infrastructure available under the programme were reviewed. Four key elements of the programme were identified: the magnitude of blindness due to cataract and the need for surgical services; the available resources; the output, in quantity and in quality, as well as the resource utilisation; and lastly the impact this has on society and the problem of blindness due to cataract. Indicators to quantify these key elements were designed and available data were used to calculate the defined indicators. RESULTS: At least 2.5 million sight restoring cataract operations will have to be performed annually. Staffing levels and infrastructure resources at present allow for increased output. The effectiveness of cataract services can be increased with better case selection. CONCLUSION: The use of these indicators provides an insight into the dynamics of the problem of cataract blindness and its intervention. They facilitate adequate management and evaluation of the efficiency and effectiveness of the intervention programme and may ensure optimal utilisation of the available resources for cataract surgery.

https://bjo.bmj.com/content/bjophthalmol/80/11/951.full.pdf

D. Bachani

Papers

Monitoring and evaluating cataract intervention in India.