A proposed rapid methodology to assess the prevalence and causes of blindness and visual impairment

The Rapid Assessment of Avoidable Blindness survey: Review of the methodology and protocol for the seventh version (RAAB7)

The Rapid Assessment of Avoidable Blindness (RAAB) is a population-based cross-sectional survey methodology used to collect data on the prevalence of vision impairment and its causes and eye care service indicators among the population 50 years and older. RAAB has been used for over 20 years with modifications to the protocol over time reflected in changing version numbers; this paper describes the latest version of the methodology-RAAB7. RAAB7 is a collaborative project between the International Centre for Eye Health and Peek Vision with guidance from a steering group of global eye health stakeholders. We have fully digitised RAAB, allowing for fast, accurate and secure data collection. A bespoke Android mobile application automatically synchronises data to a secure Amazon Web Services virtual private cloud when devices are online so users can monitor data collection in real-time. Vision is screened using Peek Vision's digital visual acuity test for mobile devices and uncorrected, corrected and pinhole visual acuity are collected. An optional module on Disability is available. We have rebuilt the RAAB data repository as the end point of RAAB7's digital data workflow, including a front-end website to access the past 20 years of RAAB surveys worldwide. This website ( https://www.raab.world) hosts open access RAAB data to support the advocacy and research efforts of the global eye health community. Active research sub-projects are finalising three new components in 2024-2025: 1) Near vision screening to address data gaps on near vision impairment and effective refractive error coverage; 2) an optional Health Economics module to assess the affordability of eye care services and productivity losses associated with vision impairment; 3) an optional Health Systems data collection module to support RAAB's primary aim to inform eye health service planning by supporting users to integrate eye care facility data with population data.

Blindness and visual impairment and their causes in India: Results of a nationally representative survey

Introduction

Avoidable blindness is a significant public health problem in India. Nationally representative RAAB surveys (Rapid Assessment of Avoidable Blindness) are being conducted periodically in the country to know the current status of blindness in the country. The current study describes the findings from the RAAB survey conducted during 2015–19 in India.

Methodology

A cross-sectional, population-based survey was conducted across the entire country among persons aged 50 years and above using RAAB version 6 methodology. Presenting and pinhole visual acuity was recorded followed by lens examination using a torchlight. In order to estimate the prevalence of blindness and visual impairment in overall population in India, district weights were assigned to each of the 31 surveyed districts and the prevalence was standardized using the RAAB software.

Results

The overall weighted, age-gender standardized, prevalence of blindness (presenting visual acuity <3/60 in better eye) in population aged ≥50 years was 1.99% (95% CI 1.94%, 2.13%) and of visual impairment (VI) (presenting visual acuity <6/12 in better eye) was 26.68% (95% CI 26.57–27.17%). On multivariate analysis, adjusted odds ratio showed that blindness was associated with age ≥ 80 years (OR = 20.3, 95% CI: 15.6–26.4) and being illiterate (OR = 5.6, 95% CI: 3.6–8.9). Blindness was not found to be significantly associated with either gender or locality.

Conclusion

The results of the survey demonstrate that currently more than one fourth of persons aged 50 years and above are visually impaired (PVA<6/12 in better eye) in India. The prevalence of blindness among them is 1.99%, and older age and illiteracy are significantly associated with blindness. Major causes of blindness included cataract (66.2%), corneal opacity (CO) (8.2%), cataract surgical complications (7.2%), posterior segment disorders (5.9%) and glaucoma (5.5%). The proportion of blindness and visual impairment that is due to avoidable causes include 92.9% and 97.4% respectively.

Primary health care facility readiness to implement primary eye care in Nigeria: equipment, infrastructure, service delivery and health management information systems

Background

Over two-thirds of Africans have no access to eye care services. To increase access, the World Health Organization (WHO) recommends integrating eye care into primary health care, and the WHO Africa region recently developed a package for primary eye care. However, there are limited data on the capacities needed for delivery, to guide policymakers and implementers on the feasibility of integration. The overall purpose of this study was to assess the technical capacity of the health system at primary level to deliver the WHO primary eye care package. Findings with respect to service delivery, equipment and health management information systems (HMIS) are presented in this paper.

Methods

This was a mixed-methods, cross sectional feasibility study in Anambra State, Nigeria. Methods included a desk review of relevant Nigerian policies; a survey of 48 primary health facilities in six districts randomly selected using two stage sampling, and semi-structured interviews with six supervisors and nine purposively selected facility heads. Quantitative study tools included observational checklists and questionnaires. Survey data were analysed descriptively using STATA V.15.1 (Statcorp, Texas). Differences between health centres and health posts were analysed using the z-test statistic. Interview data were analysed using thematic analysis assisted by Open Code Software V.4.02.

Results

There are enabling national health policies for eye care, but no policy specifically for primary eye care. 85% of facilities had no medication for eye conditions and one in eight had no vitamin A in stock. Eyecare was available in < 10% of the facilities. The services delivered focussed on maternal and child health, with low attendance by adults aged over 50 years with over 50% of facilities reporting ≤10 attendances per year per 1000 catchment population. No facility reported data on patients with eye conditions in their patient registers.

Conclusion

A policy for primary eye care is needed which aligns with existing eye health policies. There are currently substantial capacity gaps in service delivery, equipment and data management which will need to be addressed if eye care is to be successfully integrated into primary care in Nigeria.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12913-021-07359-3.

A Systematic Review of the Proportion of Blindness in the Population 50 Years and Older from Total Population-Based Surveys of Blindness and Visual Impairment

Purpose: Epidemiological data is essential for planning; however, all-age population-based surveys are resource intensive. Rapid Assessment of Cataract Surgical Services methodology was developed in India in 1995 and subsequently promoted by the World Health Organisation for use worldwide. The commonly used Rapid Assessment of Avoidable Blindness (RAAB) evolved from this in 2005, constraining surveys to populations aged 50 or more based on the report 'The Epidemiology of Blindness in Nepal' (SEVA, 1988), where 78.7% of blindness occurred in people aged 50+. The purpose of this study is to examine whether more recent total-population-based surveys continue to find a similar proportion of blindness in the population aged 50+.Methods:A systematic literature review identified all population-based surveys of blindness published 1996-2017. Data extraction was undertaken by two independent researchers and compared.Results:The proportions of blindness (presenting visual acuity (PVA) <3/60) and moderate/severe visual impairment (MSVI) (PVA <6/18-3/60) from total population-based surveys in people aged 50+ ranged from 90% (Mali, 1996) to 45.8% (South Korea, 2015); the mean proportions across all surveys were 73.1% (95% CI, 60.4-85.8%) for blindness, and 73.8% (95% CI, 54.8-92.8) for MSVI. No trend over time or association with GDP was identified.Conclusion:This systematic literature review supports the rationale for constraining surveys to the population aged 50+ as this will greatly reduce sample size but still include a high proportion of total cases of blindness; paucity of total population-based surveys highlights the ongoing need for RAAB in service planning internationally.

The Gambia National Eye Health Survey 2019: survey protocol

Two national surveys of vision impairment and blindness were undertaken in The Gambia in 1986 and 1996. These provided data for the inception of The Gambia's National Eye Health Programme (NEHP) within the Ministry of Health and Social Welfare. There have been important developments in the eye health services provided by the NEHP in the last 20 years. At the same time, the population has also undergone major demographic changes that may have led to substantial changes in the burden of eye disease. We conducted a National Eye Health Survey of vision impairment, blindness and its comorbidities in adults in The Gambia in 2019. We examined a nationally representative population-based sample of adults 35 years and above to permit direct comparison with the data available from the previous surveys. Alongside a comprehensive vision and eye examination, the survey provides nationally representative data on important comorbidities in this population: diabetes, hypertension, obesity, hearing impairment, disability and mental health. Secondly, it estimates access to assistive technologies and eye health services. Thirdly, it is powered to allow a five-year follow up cohort study to measure the incidence and progression of eye disease.

The Gambia National Eye Health Survey 2019: survey protocol

Two national surveys of vision impairment and blindness were undertaken in The Gambia in 1986 and 1996. These provided data for the inception of The Gambia's National Eye Health Programme (NEHP) within the Ministry of Health and Social Welfare. There have been important developments in the eye health services provided by the NEHP in the last 20 years. At the same time, the population has also undergone major demographic changes that may have led to substantial changes in the burden of eye disease. We conducted a National Eye Health Survey of vision impairment, blindness and its comorbidities in adults in The Gambia in 2019. We examined a nationally representative population-based sample of adults 35 years and above to permit direct comparison with the data available from the previous surveys. Alongside a comprehensive vision and eye examination, the survey provides nationally representative data on important comorbidities in this population: diabetes, hypertension, obesity, hearing impairment, disability and mental health. Secondly, it estimates access to assistive technologies and eye health services. Thirdly, it is powered to allow a five-year follow up cohort study to measure the incidence and progression of eye disease.

Rapid assessment of avoidable blindness and cataract surgery coverage among forcibly displaced Myanmar Nationals (Rohingya refugees) in Cox's Bazar, Bangladesh

Aim

To determine the prevalence and causes of blindness, vision impairment and cataract surgery coverage among Rohingya refugees aged ≥ 50 years residing in camps in Cox’s Bazar, Bangladesh.

Methods

We used the Rapid Assessment of Avoidable Blindness (RAAB) methodology to select 76 clusters of 50 participants aged ≥ 50 years with probability proportionate to size. Demographic and cataract surgery data were collected using questionnaires, visual acuity was assessed per World Health Organization criteria and examinations were conducted by torch, and with direct ophthalmoscopy in eyes with pinhole-corrected vision <6/12. RAAB software was used for data entry and analysis.

Results

We examined 3,629 of 3800 selected persons (95.5%). Age and sex adjusted prevalence of blindness (<3/60), severe visual impairment (SVI; >3/60 to ≤6/60), moderate visual impairment (MVI; >6/60 to ≤6/18), and early visual impairment (EVI; >6/18 to ≤6/12) were 2.14%, 2.35%, 9.68% and 14.7% respectively. Cataract was responsible for 75.0% of blindness and 75.8% of SVI, while refractive error caused 47.9% and 90.9% of MVI and EVI respectively. Most vision loss (95.9%) was avoidable. Cataract surgical coverage among the blind was 81.2%. Refractive error was detected in 17.1% (n = 622) of participants and 95.2% (n = 592) of these did not have spectacles. In the full Rohingya cohort of 76,692, approximately 10,000 surgeries are needed to correct all eyes impaired (<6/18) by cataract, 12,000 need distance glasses and 73,000 require presbyopic correction.

Conclusion

The prevalence of blindness was lower than expected for a displaced population, in part due to few Rohingya being ≥60 years and the camp’s good access to cataract surgery. We suggest the United Nations High Commissioner for Refugees include eye care among recommended health services for all refugees with long-term displacement.

Rapid Assessment of Avoidable Blindness and Willingness to Pay for Cataract Surgery in Tribal Region of Surat District of Gujarat State, India

AIM

To estimate prevalence and causes of avoidable blindness among people ≥50 years and to assess willingness to pay (WTP) for cataract surgery in tribal region of south Gujarat, India.

METHODS

A cross-sectional population based survey was conducted with 44 randomly selected clusters each having 50 people aged ≥50 years selected by probability proportional to size of sampling. Adults identified with cataract causing visual loss (<6/18) in any eye were interviewed to assess their WTP for surgery.

RESULTS

Total of 2137 examined out of 2200 people enumerated (response rate 97.1%). The prevalence of blindness (Presenting Visual Acuity (PVA)<3/60 in better eye) was 2.23% (95% CI: 2.95%-1.51%). Cataract was main cause of blindness (67.3%) followed by corneal scarring (8.2%). Major barrier to cataract surgery cited by bilaterally blind people was lack of escort to the surgical facility (34.3%). Cataract surgical coverage (CSC) was 84.9% (eyes) and 92% (persons). Of the 492 people interviewed to assess WTP for their surgery, only 36.4% people were willing to pay.

CONCLUSION

The tribal population has a high poverty profile in India. Within this group, cataract remains the main treatable cause of blindness despite a high CSC. Assessment of barriers suggested that a well-coordinated outreach programme with free transport facilities to the surgical facility is required along with strategies to improve accessibility and prioritising cataract blind in the community. One-third of people were willing to pay for their surgeries implying that cross subsidization or tier system could be feasible for eye care programme sustainability.

Prevalence of Visual Impairment and Coverage of Cataract Surgical Services: Associations with Sex, Disability, and Economic Status in Five Diverse Sites

PURPOSE

Prevalence of visual impairment (VI) and access to services can vary significantly across and between different population groups. With renewed focus on universal health coverage and leaving no one behind, it is important to understand factors driving inequitable eye health. This paper presents results from five population-based surveys where prevalence of VI and cataract surgical coverage (CSC) were measured and examined for differences by sex, economic-status, and disability.

METHODS

Rapid assessments of avoidable blindness took place in four rural sites: Kalahandi, Jhabua and Sitapur in India; and Singida, Tanzania; and one urban site: Lahore, Pakistan. In addition, the Equity Tool was used to measure economic status and the Washington Group Short Set was used to measure disability. Prevalence of VI and CSC were calculated and associations with sex, disability, and relative wealth examined.

RESULTS

Prevalence of VI varied from 1.9% in Lahore to 15.0% in Kalahandi. CSC varied from 39.1% in Singida to 84.0% in Lahore. Additional disability was associated with greater levels of VI in all sites and lower CSC in Singida. Being female was associated with higher VI in Kalahandi, Lahore and Singida and lower CSC in Lahore and Singida. Being poorer was associated with higher VI in Singida and lower CSC in Singida and Sitapur.

CONCLUSION

Relationships between VI and relative wealth, sex, and disability are complex and variable. Although certain characteristics may be associated with lower coverage or worse outcomes, they cannot be generalized and local data are vital to tailor services to achieve good coverage.

Blindness above and below the Poverty Line: Reflections form Sofala, Mozambique

Although the correlation between visual impairment and poverty has been established, economic assessment is not a standard component of blindness surveys. The purpose of this study was to determine the prevalence of avoidable blindness and its association with poverty in Sofala province of Mozambique. As part of a Rapid Assessment of Avoidable Blindness, 94% of a random sample of 3600 people >50 years responded to questions regarding daily per capita expenditure. The WHO definition of blindness (presenting visual acuity <3/60) was used to determine the visual status of participants, and the World Bank's threshold of living on <$1.25 International Dollar a day demarcated the poverty line. The prevalence of blindness was 3.2% [95% Confidence Interval (CI): 2.6, 3.8]. People living below the poverty line had significantly greater odds of being blind [Odds Ratio (OR): 2.6 (CI: 1.6 to 4.5)]. Age above 60 [OR: 7.0 [CI: 4.6 to 10.80] predicted blindness but the association with illiteracy, gender or rural residence was not significant. Blindness disproportionately affects people living below the poverty line. Development initiatives could augment the impact of blindness prevention programs. Measuring poverty should become a standard component of visual impairment surveys.

Rationale and feasibility of a combined rapid assessment of avoidable blindness and hearing loss protocol

Purpose

This study has two main objectives: 1) to assess the value of combining the rapid assessment of avoidable blindness (RAAB) and the recently developed rapid assessment of hearing loss (RAHL) based on existing population-based data from Cameroon andIndia; 2) to test the feasibility of a combined RAAB-RAHL protocol.

Methods

A secondary data analysis of population-based disability surveys in India and Cameroon (in 2013–2014) was conducted, focussing on people aged 50+. Hearing impairment (HI) was defined as pure tone average of ≥41dB (better ear).Visual impairment (VI) was defined as presenting visual acuity of <6/18 (better eye). The relationship between HI and VI was examined. The feasibility of a combined RAAB-RAHL survey was assessed within a RAHL conducted among adults aged 50+ in Malawi in 2018. Outcomes included: time taken, costs, number of people examined in a day, and qualitative feedback from participants and field teams.

Results

The prevalence of combined VI and HI among people aged 50+ was 4.4% (95% confidence interval (CI) 3.0, 6.4) in India and 4.8% (95%CI 3.0, 8.0) in Cameroon. Among participants with VI, approximately a third in India (29.3%) and Cameroon (35.1%) also had HI. A quarter of participants in India (25.4%) and Cameroon (26.9%) who had HI also had VI. In Malawi, the total time taken to complete both RAAB and RAHL assessments was approximately 27 minutes per participant. It was feasible to complete 30 participants per day for a team of four people. The estimated cost of a combined RAAB-RAHL approach in comparison to two separate impairment surveys is up to 37% less depending on the method of combination.

Conclusion

The substantial overlap between VI and HI supports a combined rapid survey of the two impairments. The pilot study of a combined RAAB-RAHL survey demonstrates feasibility and lower cost compared to conducting two standalone impairment surveys. A combined RAAB-RAHL approach could maximize limited resources to increase prevalence data for both vision and hearing impairment.

Rationale for a Rapid Methodology to Assess the Prevalence of Hearing Loss in Population-Based Surveys

Data on the prevalence and causes of hearing loss is lacking from many low and middle-income countries, in part, because all-age population-based surveys of hearing loss can be expensive and time consuming. Restricting samples to older adults would reduce the sample size required, as hearing loss is more prevalent in this group. Population-based surveys of hearing loss require clinicians to be involved in the data collection team and reducing the duration of the survey may help to minimise the impact on service delivery. The objective of this paper was to identify the optimal age-group for conduct of population-based surveys of hearing loss, balancing sample size efficiencies, and expected response rates with ability to make inferences to the all-age population. Methods: Between 2013–2014, two all aged population-based surveys of hearing loss were conducted in one district each of India and Cameroon. Secondary data analysis was conducted to determine the proportion of hearing loss (moderate or greater) in people aged 30+, 40+ and 50+. Poisson regression models were developed to predict the expected prevalence of hearing loss in the whole population, based on the prevalence in people aged 30+, 40+, and 50+, which was compared to the observed prevalence. The distribution of causes in these age groups was also compared to the all-age population. Sample sizes and response rates were estimated to assess which age cut-off is most rapid. Results: Of 160 people in India and 131 in Cameroon with moderate or greater hearing loss, over 70% were older than 50 in both settings. For people aged 30+ (90.6% India; 76.3% Cameroon), 40+ (81% India; 75% Cameroon) and 50+ (73% India; 73% Cameroon) the proportions were higher. Prediction based on Poisson distributed observations the predicted prevalence based on those aged 30+, 40+, and 50+ fell within the confidence intervals of the observed prevalence. The distribution of probable causes of hearing loss in the older age groups was statistically similar to the total population. Sample size calculations and an analysis of response rates suggested that a focus on those aged 50+ would minimise costs the most by reducing the survey duration. Conclusion: Restricting the age group included in surveys of hearing loss, in particular to people aged 50+, would still allow inferences to be made to the total population, and would mean that the required sample size would be smaller, thus reducing the duration of the survey and costs.

Generating evidence for planning eye care service delivery in an urban underprivileged population setting in Pune, Western India

Purpose

To estimate prevalence of blindness, diabetic retinopathy and causes of blindness through rapid assessment of avoidable blindness (RAAB) survey in Pune, India to develop an evidence base for planning urban eye care services.

Methods

‘Rapid assessment of avoidable blindness and diabetic retinopathy’ methodology was used. Compact segment sampling was used in each of the 60 selected electoral wards identified through cluster selection module of the RAAB software using probability proportionate to size method. Persons >50 years of age were enumerated from selected segments to achieve cumulative target of 60/day by two teams. Participants underwent presenting and pinhole visual acuity (VA) testing in each eye. A torch light examination and direct ophthalmoscopy established cause of visual impairment/blindness if present. Data were entered into and analysed using RAAB software.

Results

The response rate was 89.5% (3221/3600), and 55.3% were women. Results of only RAAB module are presented in this paper. Age-standardised and sex-standardised prevalence of blindness was 1.3% (95% CI 0.9 to 1.8). Cataract was the most common cause of blindness (45.7%) followed by overall posterior segment disorders (39.1%). Cataract surgical outcome was good (VA>6/18) or very good (VA>6/12) in 805/1190 (67.6%) cases. Cataract surgical coverage was 96.7%. ‘Need not felt’ (36.6%) and ‘cost’ (31.7%) were the most common barriers for cataract surgery.

Conclusion

Prevalence of blindness is showing declining trend in urban India. Cataract remains a major cause of blindness followed by posterior segment disorders. Social marketing, and referral linkages between community and service providers were planned after this survey.

Rapid Assessment of Avoidable Blindness: looking back, looking forward

The Rapid Assessment of Avoidable Blindness, or RAAB, is a relatively simple and low-cost survey methodology to provide data on the prevalence and causes of visual loss. The aim of this article is to reflect on the achievements and challenges of RAAB, and to describe the future developments that are needed to ensure that it remains a relevant and widely used tool. To date, at least 331 RAABs have been undertaken in 79 countries, and these surveys provide an important source of information on visual loss at both the local and global level. A RAAB repository has been developed which includes the site and date of RAABs undertaken, and, where authors have agreed, the core indicators, reports or even raw data from the survey. This dataset has already been used for meta-analyses, and there are further opportunities for its use. Despite these achievements, there are core areas in which RAAB needs to be strengthened so that the full benefits of undertaking the survey can be reaped. Key developments of RAAB are underway, and will include greater use of mobile technologies using a cloud-based platform to enable both digital data collection, real-time survey reviews, reporting and analysis, and a greater emphasis on using the data for planning.

Incidence of Visually Impairing Cataracts Among Older Adults in Kenya

Importance

Half of all the cases of blindness worldwide are associated with cataract. Cataract disproportionately affects people living in low- and middle-income countries and persons of African descent.

Objective

To estimate the 6-year cumulative incidence of visually impairing cataract in adult participants in the Nakuru Eye Disease Cohort Study in Kenya.

Design, Setting, and Participants

This secondary analysis of the Nakuru Eye Disease Cohort Study was conducted from February 2016 to April 2016. This cohort comprised citizens of Nakuru, Kenya, aged 50 years or older who consented to participate in the initial or baseline survey from January 2007 to November 2008, as well as the follow-up conducted from January 2013 to March 2014. All participants at baseline (n = 4364) and follow-up (n = 2159) underwent ophthalmic examination.

Main Outcomes and Measures

Six-year cumulative incidence of visually impairing cataract, risk factors of incidence, population estimates, and required cataract surgical rates to manage incident visually impairing cataract.

Results

In total, 4364 individuals (with a mean [SD] age of 63.4 [10.5] years and with 2275 women [52.1%]) had complete eye examinations at baseline, and 2159 participants (with a mean [SD] age of 62.5 [9.3] years and with 1140 men [52.8%]) were followed up 6 years later. The 6-year cumulative incidence of visually significant cataract in either eye was 251.9 per 1000 (95% CI, 228.5-276.8), with an increase with age from 128.9 (95% CI, 107.9-153.2) per 1000 for the group aged 50 to 59 years to 624.5 (95% CI, 493.1-739.9) per 1000 for the group aged 80 years or older. This equated to an annual incidence of visually significant cataract of 45.0 per 1000 people aged 50 years or older. Multivariable analysis showed alcohol consumption (risk ratio [RR], 1.4; 95% CI, 1.1-1.8), diabetes (RR, 1.7; 95% CI, 1.3-2.3), educational level, and increasing age (RR, 3.8; 95% CI, 2.6-5.5 for those aged ≥80 years) were associated with incident visually impairing cataract. Extrapolations to all people aged 50 years or older in Kenya indicated that 148 280 (95% CI, 134 510-162 950) individuals might develop new visually impairing cataract in either eye (visual acuity <6/18 in the worse-seeing eye) and that 9540 (95% CI, 6610-13 750) might become cataract blind in both eyes (visual acuity <3/60 in better-seeing eye).

Conclusions and Relevance

Adults in Kenya appeared to have a high incidence of visually impairing cataract, making cataract a priority for blindness prevention programs in the region; surgical interventions and awareness of these services are also required.

Changing trends of blindness, visual impairment and cataract surgery in Bhutan: 2009-2018

Purpose

To obtain new rapid assessment of avoidable blindness (RAAB) data on the prevalence, causes and trends of blindness, visual impairment and cataract surgery; and compare the new 2018 data with the older RAAB 2009 data.

Methodology

The second nationwide RAAB used android based mRAAB technique and technology for data collection. Using the compact segment sampling probability proportionate to size, 5,050 participants from 101 clusters of 50 people aged 50 years and older were enrolled through house-to-house visits. Eligible participants received ophthalmic examination and interview by the ophthalmologist-led emuneration team as per the RAAB protocol.

Results

The age-sex adjusted magnitude of bilateral blindness in Bhutan was 1.0% (95% Confidence Interval, CI 0.5–1.4) with relatively higher prevalence in rural population (Odds Ratio, OR 1.5, p = 0.13) and women (OR 1.6, p = 0.06). Untreated cataract accounted for the most of blindness (53.8%), severe vision impairment (57.1%), and moderate visual impairment (65.3%); uncorrected refractive error was the main cause of early visual impairment (46.7%). Cataract Surgical Coverage was 86.1% with relatively better coverage in men (76.7% men; 73.1% female) and urban population (79.2% urban; 70.2% rural). Good cataract surgical outcome was achieved in 67.3% and leading cause of poor outcome was ocular comorbidity (43.6%). Accessibility was a significant barrier to the uptake of cataract surgical services.

Conclusion

There is a 33% reduction in blindness from 1.5% to 1.0%, since the first RAAB survey in 2009. In order to further reduce blindness and visual impairment, Bhutan should continue to implement long-term strategic action plan for eye health focused on strengthening primary eye care and comprehensive eye care service.

Estimating the magnitude of diabetes mellitus and diabetic retinopathy in an older age urban population in Pune, western India

Objective

To estimate magnitude of diabetes mellitus (DM) and diabetic retinopathy (DR) in a high risk population in Pune, western India.

Methods

DR module in rapid assessment of avoidable blindness (RAAB) survey methodology was used. Sample size of 3527 was calculated based on estimates from previous studies in India. A certified RAAB trainer conducted a training of survey teams. Random cluster sampling with probability proportionate to size was adapted to select 60 clusters consisting of 60 individuals each. Two teams visited door to door until they finished visiting 60 persons each day. Visual acuity testing, torch light examination, red glow test were carried out to determine persons with visual impairment and its cause. Every participant then underwent a random blood sugar level testing. All diabetics (known and newly detected) underwent dilated retina evaluation with indirect ophthalmoscopy to determine their DR status. Data were entered into RAAB6 software and descriptive statistics generated.

Results

Response rate was 89.5 % (3221/3600), females (55.3%). The prevalence of DM in the sample was (706/3221) 21.9 %(95 CI 20.1 to 23.7). Prevalence of DR was 14.3 % (95% CI 11.7 to 16.9). Most diabetics (401/579, 69.3%) never had an eye examination for DR in the past. Cataract was the principal cause of blindness (50 % cases) among diabetics.

Conclusion

DM affects over fifth of persons above 50 years of age in western India. Nearly seventh of the diabetics have DR, but coverage of screening is poor in Pune.

Evidence for national universal eye health plans

Many low- and middle-income countries use national eye-care plans to guide efforts to strengthen eye-care services. The World Health Organization recognizes that evidence is essential to inform these plans. We assessed how evidence was incorporated in a sample of 28 national eye-care plans generated since the Universal eye health: a global action plan 2014-2019 was endorsed by the World Health Assembly in 2013. Most countries (26, 93%) cited estimates of the prevalence of blindness and 18 countries (64%) had set targets for the cataract surgical rate in their plan. Other evidence was rarely cited or used to set measurable targets. No country cited evidence from systematic reviews or solution-based research. This limited use of evidence reflects its low availability, but also highlights incomplete use of existing evidence. For example, despite sex-disaggregated data and cataract surgical coverage being available from surveys in 20 countries (71%), these data were reported in the eye health plans of only nine countries (32%). Only three countries established sex-disaggregated indicators and only one country had set a target for cataract surgical coverage for future monitoring. Countries almost universally recognized the need to strengthen health information systems and almost one-third planned to undertake operational or intervention research. Realistic strategies need to be identified and supported to translate these intentions into action. To gain insights into how a country can strengthen its evidence-informed approach to eye-care planning, we reflect on the process underway to develop Kenya's seventh national plan (2019-2023).

Estimates of visual impairment and its causes from the National Eye Survey in Malaysia (NESII)

BACKGROUND

Population-based data on prevalence, causes of blindness and extent of ophthalmological coverage is required for efficient implementation and evaluation of ocular health programs. In view of the scarcity of prevalence data for visual impairment and blindness in Malaysia, this study aims to estimate the prevalence and causes of visual impairment (VI) in the elderly, using Rapid Assessment of Avoidable Blindness (RAAB) survey technique.

METHODS

Malaysia was divided into six regions, with each region consisting of 50 clusters. Multistage cluster sampling method was used and each cluster contained 50 residents aged 50 years and above. Eligible subjects were interviewed and pertinent demographic details, barriers to cataract surgery, medical and ocular history was noted. Subjects had visual acuity assessment with tumbling 'E' Snellen optotypes and ocular examination with direct ophthalmoscope. The primary cause of VI was documented. Results were calculated for individual zones and weighted average was used to obtain overall prevalence for the country. Inter-regional and overall prevalence for blindness, severe VI and moderate VI were determined. Causes of VI, cataract surgical coverage and barriers to cataract surgery were assessed.

RESULTS

A total of 15,000 subjects were examined with a response rate of 95.3%. The age and gender-adjusted prevalence of blindness, severe visual impairment and moderate visual impairment were 1.2% (95% Confidence Interval: 1.0-1.4%), 1.0% (95%CI: 0.8-1.2%) and 5.9% (5.3-6.5%) respectively. Untreated cataract (58.6%), diabetic retinopathy (10.4%) and glaucoma (6.6%) were the commonest causes of blindness. Overall, 86.3% of the causes of blindness were avoidable. Cataract surgical coverage (CSC) in persons for blindness, severe visual impairment and moderate visual impairment was 90%, 86% and 66% respectively.

CONCLUSION

Increased patient education and further expansion of ophthalmological services are required to reduce avoidable blindness even further in Malaysia.

A population-based survey of visual impairment and its correlates in Mahabubnagar district, Telangana State, India

PURPOSE

To estimate the prevalence and correlates of visual impairment in Mahabubnagar district, Telangana, India.

METHODS

Fifty-one clusters of 80 people (all ages) were sampled with probability proportionate to size. Households within clusters were selected through the compact segment sampling. Visual acuity (VA) was measured with a tumbling "E" chart. An Ophthalmic Assistant or Vision Technician examined people with VA<6/12 in either eye. Other impairments (hearing, physical) were clinically assessed and self-reported functional difficulties measured using the Washington Group Extended Set. People with visual impairment and age-sex matched controls with normal vision were interviewed about poverty, employment and education.

RESULTS

4,125 people were enumerated and 3,574 screened (86.6%). The prevalence of visual impairment (VA<6/12) was 8.0% (95% CI = 6.9-9.4%) and blindness was 0.4% (0.2-0.9%), and both increased rapidly with age. Uncorrected refractive error was the leading cause of visual impairment, and cataract the leading cause of blindness. Cataract surgical coverage (proportion of all cataracts that had received surgery) was relatively low (41% of people at VA<6/60), while the post-surgery outcomes were good (81% of operated eyes had presenting VA≥6/18). Among the 287 people with visual impairment, 15% had a moderate/severe physical impairment or epilepsy and 25% had a moderate/severe hearing impairment. Self-reported difficulties in vision were relatively closely related to visual acuity. People with visual impairment were more likely to be in the poorest quartile (OR = 1.9, 95% CI = 1.0-3.4) or unemployed (5.0, 2.2-10.0), compared to controls.

CONCLUSIONS

Visual impairment was common in Mahabubnagar district, was mostly avoidable, and was correlated with poverty markers.

Interventions to improve access to cataract surgical services and their impact on equity in low- and middle-income countries

BACKGROUND

Cataract is the leading cause of blindness in low- and middle-income countries (LMICs), and the prevalence is inequitably distributed between and within countries. Interventions have been undertaken to improve cataract surgical services, however, the effectiveness of these interventions on promoting equity is not known.

OBJECTIVES

To assess the effects on equity of interventions to improve access to cataract services for populations with cataract blindness (and visual impairment) in LMICs.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (which contains the Cochrane Eyes and Vision Trials Register) (2017, Issue 3), MEDLINE Ovid (1946 to 12 April 2017), Embase Ovid (1980 to 12 April 2017), LILACS (Latin American and Caribbean Health Sciences Literature Database) (1982 to 12 April 2017), the ISRCTN registry (www.isrctn.com/editAdvancedSearch); searched 12 April 2017, ClinicalTrials.gov (www.clinicaltrials.gov); searched 12 April 2017 and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en); searched 12 April 2017. We did not use any date or language restrictions in the electronic searches for trials.

SELECTION CRITERIA

We included studies that reported on strategies to improve access to cataract services in LMICs using the following study designs: randomised and quasi-randomised controlled trials (RCTs), controlled before-and-after studies, and interrupted time series studies. Included studies were conducted in LMICs, and were targeted at disadvantaged populations, or disaggregated outcome data by 'PROGRESS-Plus' factors (Place of residence; Race/ethnicity/ culture/ language; Occupation; Gender/sex; Religion; Education; Socio-economic status; Social capital/networks. The 'Plus' component includes disability, sexual orientation and age).

DATA COLLECTION AND ANALYSIS

Two authors (JR and JP) independently selected studies, extracted data and assessed them for risk of bias. Meta-analysis was not possible, so included studies were synthesised in table and text.

MAIN RESULTS

From a total of 2865 studies identified in the search, two met our eligibility criteria, both of which were cluster-RCTs conducted in rural China. The way in which the trials were conducted means that the risk of bias is unclear. In both studies, villages were randomised to be either an intervention or control group. Adults identified with vision-impairing cataract, following village-based vision and eye health assessment, either received an intervention to increase uptake of cataract surgery (if their village was an intervention group), or to receive 'standard care' (if their village was a control group).One study (n = 434), randomly allocated 26 villages or townships to the intervention, which involved watching an informational video and receiving counselling about cataract and cataract surgery, while the control group were advised that they had decreased vision due to cataract and it could be treated, without being shown the video or receiving counselling. There was low-certainty evidence that providing information and counselling had no effect on uptake of referral to the hospital (OR 1.03, 95% CI 0.63 to 1.67, 1 RCT, 434 participants) and little or no effect on the uptake of surgery (OR 1.11, 95% CI 0.67 to 1.84, 1 RCT, 434 participants). We assessed the level of evidence to be of low-certainty for both outcomes, due to indirectness of evidence and imprecision of results.The other study (n = 355, 24 towns randomised) included three intervention arms: free surgery; free surgery plus reimbursement of transport costs; and free surgery plus free transport to and from the hospital. These were compared to the control group, which was reminded to use the "low-cost" (˜USD 38) surgical service. There was low-certainty evidence that surgical fee waiver with/without transport provision or reimbursement increased uptake of surgery (RR 1.94, 95% CI 1.14 to 3.31, 1 RCT, 355 participants). We assessed the level of evidence to be of low-certainty due to indirectness of evidence and imprecision of results.Neither of the studies reported our primary outcome of change in prevalence of cataract blindness, or other outcomes such as cataract surgical coverage, surgical outcome, or adverse effects. Neither study disaggregated outcomes by social subgroups to enable further assessment of equity effects. We sought data from both studies and obtained data from one; the information video and counselling intervention did not have a differential effect across the PROGRESS-Plus categories with available data (place of residence, gender, education level, socioeconomic status and social capital).

AUTHORS' CONCLUSIONS

Current evidence on the effect on equity of interventions to improve access to cataract services in LMICs is limited. We identified only two studies, both conducted in rural China. Assessment of equity effects will be improved if future studies disaggregate outcomes by relevant social subgroups. To assist with assessing generalisability of findings to other settings, robust data on contextual factors are also needed.

Prevalence and Causes of Visual Impairment in Fundong District, North West Cameroon: Results of a Population-Based Survey

PURPOSE

To estimate the prevalence and causes of visual impairment in Fundong Health District, North West Cameroon.

METHODS

A total of 51 clusters of 80 people (all ages) were sampled with probability proportionate to size and compact segment sampling. Visual acuity (VA) was measured with a tumbling "E" chart. An ophthalmic nurse examined people with VA<6/18 in either eye. The presence of hearing and physical impairments were assessed using clinical examination, and self-reported visual problems using the Washington Group Short Set.

RESULTS

In total, 4080 people were enumerated of whom 3567 were screened (response rate 87%). The overall prevalence of visual impairment was 2.3% (95% CI 1.8-3.0%) and blindness was 0.6% (0.3-1.0%). The prevalence of both blindness and visual impairment increased rapidly with age, so that the vast majority of cases of visual impairment (84%) and blindness (82%) were in people aged 50+. Posterior segment disease and cataract were the main causes of blindness and visual impairment, with refractive error also an important cause of visual impairment. Cataract surgical coverage (proportion of all cataracts that had received surgery) was relatively high (87% of people at VA<6/60). Post-surgery outcomes were poor, with 31% of operated eyes having VA<6/60. Among the 82 people with visual impairment, 22% had a physical impairment or epilepsy and 30% had a hearing impairment. Self-reported difficulties in vision were relatively closely related to clinical measures of visual impairment.

CONCLUSIONS

Ophthalmic programmes in Cameroon need to incorporate control of posterior segment diseases while also working to improve outcomes after cataract surgery.

Avoidable Waste in Ophthalmic Epidemiology: A Review of Blindness Prevalence Surveys in Low and Middle Income Countries 2000-2014

PURPOSE

Sources of avoidable waste in ophthalmic epidemiology include duplication of effort, and survey reports remaining unpublished, gaining publication after a long delay, or being incomplete or of poor quality. The aim of this review was to assess these sources of avoidable waste by examining blindness prevalence surveys undertaken in low and middle income countries (LMICs) between 2000 and 2014.

METHODS

On December 1, 2016 we searched MEDLINE, EMBASE and Web of Science databases for cross-sectional blindness prevalence surveys undertaken in LMICs between 2000 and 2014. All surveys listed on the Rapid Assessment of Avoidable Blindness (RAAB) Repository website ("the Repository") were also considered. For each survey we assessed (1) availability of scientific publication, survey report, summary results tables and/or datasets; (2) time to publication from year of survey completion and journal attributes; (3) extent of blindness information reported; and (4) rigour when information was available from two sources (i.e. whether it matched).

RESULTS

Of the 279 included surveys (from 68 countries) 186 (67%) used RAAB methodology; 146 (52%) were published in a scientific journal, 57 (20%) were published in a journal and on the Repository, and 76 (27%) were on the Repository only (8% had tables; 19% had no information available beyond registration). Datasets were available for 50 RAABs (18% of included surveys). Time to publication ranged from <1 to 11 years (mean, standard deviation 2.8 ± 1.8 years). The extent of blindness information reported within studies varied (e.g. presenting and best-corrected, unilateral and bilateral); those with both a published report and Repository tables were most complete. For surveys published and with RAAB tables available, discrepancies were found in reporting of participant numbers (14% of studies) and blindness prevalence (15%).

CONCLUSION

Strategies are needed to improve the availability, consistency, and quality of information reported from blindness prevalence surveys, and hence reduce avoidable waste.

Six-Year Incidence of Blindness and Visual Impairment in Kenya: The Nakuru Eye Disease Cohort Study

Purpose

To describe the cumulative 6-year incidence of visual impairment (VI) and blindness in an adult Kenyan population. The Nakuru Posterior Segment Eye Disease Study is a population-based sample of 4414 participants aged ≥50 years, enrolled in 2007–2008. Of these, 2170 (50%) were reexamined in 2013–2014.

Methods

The World Health Organization (WHO) and US definitions were used to calculate presenting visual acuity classifications based on logMAR visual acuity tests at baseline and follow-up. Detailed ophthalmic and anthropometric examinations as well as a questionnaire, which included past medical and ophthalmic history, were used to assess risk factors for study participation and vision loss. Cumulative incidence of VI and blindness, and factors associated with these outcomes, were estimated. Inverse probability weighting was used to adjust for nonparticipation.

Results

Visual acuity measurements were available for 2164 (99.7%) participants. Using WHO definitions, the 6-year cumulative incidence of VI was 11.9% (95%CI [confidence interval]: 10.3–13.8%) and blindness was 1.51% (95%CI: 1.0–2.2%); using the US classification, the cumulative incidence of blindness was 2.70% (95%CI: 1.8–3.2%). Incidence of VI increased strongly with older age, and independently with being diabetic. There are an estimated 21 new cases of VI per year in people aged ≥50 years per 1000 people, of whom 3 are blind. Therefore in Kenya we estimate that there are 92,000 new cases of VI in people aged ≥50 years per year, of whom 11,600 are blind, out of a total population of approximately 4.3 million people aged 50 and above.

Conclusions

The incidence of VI and blindness in this older Kenyan population was considerably higher than in comparable studies worldwide. A continued effort to strengthen the eye health system is necessary to support the growing unmet need in an aging and growing population.

Effective cataract surgical coverage: An indicator for measuring quality-of-care in the context of Universal Health Coverage

OBJECTIVE

To define and demonstrate effective cataract surgical coverage (eCSC), a candidate UHC indicator that combines a coverage measure (cataract surgical coverage, CSC) with quality (post-operative visual outcome).

METHODS

All Rapid Assessment of Avoidable Blindness (RAAB) surveys with datasets on the online RAAB Repository on April 1 2016 were downloaded. The most recent study from each country was included. By country, cataract surgical outcome (CSOGood, 6/18 or better; CSOPoor, worse than 6/60), CSC (operated cataract as a proportion of operable plus operated cataract) and eCSC (operated cataract and a good outcome as a proportion of operable plus operated cataract) were calculated. The association between CSC and CSO was assessed by linear regression. Gender inequality in CSC and eCSC was calculated.

FINDINGS

Datasets from 20 countries were included (2005-2013; 67,337 participants; 5,474 cataract surgeries). Median CSC was 53.7% (inter-quartile range[IQR] 46.1-66.6%), CSOGood was 58.9% (IQR 53.7-67.6%) and CSOPoor was 17.7% (IQR 11.3-21.1%). Coverage and quality of cataract surgery were moderately associated-every 1% CSC increase was associated with a 0.46% CSOGood increase and 0.28% CSOPoor decrease. Median eCSC was 36.7% (IQR 30.2-50.6%), approximately one-third lower than the median CSC. Women tended to fare worse than men, and gender inequality was slightly higher for eCSC (4.6% IQR 0.5-7.1%) than for CSC (median 2.3% IQR -1.5-11.6%).

CONCLUSION

eCSC allows monitoring of quality in conjunction with coverage of cataract surgery. In the surveys analysed, on average 36.7% of people who could benefit from cataract surgery had undergone surgery and obtained a good visual outcome.

Solar ultraviolet radiation in Africa: a systematic review and critical evaluation of the health risks and use of photoprotection

The majority of the African continent experiences high solar UVB radiation throughout the year. The adverse consequences of this on the health of populations living in Africa are reviewed.

Prevalence, causes of blindness, visual impairment and cataract surgical services in Sindhudurg district on the western coastal strip of India

Background:

Konkan coast of India is geographically distinct and its pattern of blindness has never been mapped.

Aim:

To study the prevalence and causes of blindness and cataract surgical services in Sindhudurg district of West Coast.

Subjects:

Individual aged > 50 years.

Materials and Methods:

Rapid assessment of avoidable blindness used to map blindness pattern in the district. Statistical analysis: SPSS version 19.

Results:

Amongst those examined 1415 (51.7%) had visual acuity (VA) >20/60, 924 (33.8%, confidence interval (C.I) 30.5%-36.8%) had VA 20/200-<20/60(visual impairment), 266 (9.7%, C.I. 6.1%-13.3%) had VA < 20/200-20/400 (severe visual impairment) and 132 (4.8%, C. I. 1.1%-8.5%) had VA < 20/400 (blindness by WHO standards). There was no significant gender difference in prevalence of blindness, but blindness and visual impairment was more in older and rural residing individuals. Amongst those with presenting vision < 20/200 in better eye, 309 (82.4%) had cataract, 36 (9.7%) had corneal scars, 13 (3.5%) had diabetic retinopathyand 3 (0.8%) had glaucoma. Cataract surgical coverage for the district was only 30.5%; 32% for males and 28.4% for females. Unable to afford, lack of knowledge and lack of access to services were the commonest barriers responsible for cataract patients not seeking care. Amongst those who had undergone cataract surgery, only 50% had visual acuity ≥ 20/60.46.9% of the population had spectacles for near, but only 53.3% of the population had presenting near vision < N10.

Conclusion:

Cataract, refractive errors and diabetes were significant causes of visual impairment and blindness.

Prevalence of blindness and cataract surgical outcomes in Takeo Province, Cambodia

PURPOSE

To estimate the prevalence of blindness and cataract surgical outcomes in persons 50 years or older above in Takeo Province, Cambodia.

DESIGN

A population based survey.

METHODS

A total of 93 villages were selected through probability proportionate to size using the Rapid Assessment of Avoidable Blindness methodology. Households from 93 villages were selected using compact segment sampling. Visual acuity (VA) of 4650 people 50 years or older was tested and lens status and cause of visual impairment were assessed.

RESULTS

The response rate was 96.2%. The age- and sex-adjusted prevalence of bilateral blindness [presenting visual acuity (PVA) <3/60 in the better eye] was 3.4% (95% confidence interval, 2.8%-4.0%), resulting in an estimated 4187 people blind in Takeo Province. The age- and sex-adjusted prevalence of low vision (PVA <6/18 to 3/60) was 21.1%, an estimated 25,900 people. Cataract surgical coverage in the bilaterally blind was 64.7% (female 59.5%, male 78.1%). Cataract surgical outcome was poor (best-corrected visual acuity <6/60) in only 7.7% and good in 88.7% (best-corrected visual acuity ≥6/18) of eyes operated in the last 5 years before the survey.

CONCLUSIONS

The cataract surgical coverage for women is less than that for men. The increased life expectancy in Cambodia and the fact that women constitute 60.6% of the population (aged ≥50 years) at Takeo Province could have had an impact on cataract workload and high prevalence of blindness. A repeated survey using the same methodology after 8-12 years might be helpful in proving genuine change over time.

The first rapid assessment of avoidable blindness (RAAB) in Thailand

BACKGROUND

The majority of vision loss is preventable or treatable. Population surveys are crucial for planning, implementation, and monitoring policies and interventions to eliminate avoidable blindness and visual impairments. This is the first rapid assessment of avoidable blindness (RAAB) study in Thailand.

METHODS

A cross-sectional study of a population in Thailand age 50 years old or over aimed to assess the prevalence and causes of blindness and visual impairments. Using the Thailand National Census 2010 as the sampling frame, a stratified four-stage cluster sampling based on a probability proportional to size was conducted in 176 enumeration areas from 11 provinces. Participants received comprehensive eye examination by ophthalmologists.

RESULTS

The age and sex adjusted prevalence of blindness (presenting visual acuity (VA) <20/400), severe visual impairment (VA <20/200 but ≥20/400), and moderate visual impairment (VA <20/70 but ≥20/200) were 0.6% (95% CI: 0.5-0.8), 1.3% (95% CI: 1.0-1.6), 12.6% (95% CI: 10.8-14.5). There was no significant difference among the four regions of Thailand. Cataract was the main cause of vision loss accounted for 69.7% of blindness. Cataract surgical coverage in persons was 95.1% for cut off VA of 20/400. Refractive errors, diabetic retinopathy, glaucoma, and corneal opacities were responsible for 6.0%, 5.1%, 4.0%, and 2.0% of blindness respectively.

CONCLUSION

Thailand is on track to achieve the goal of VISION 2020. However, there is still much room for improvement. Policy refinements and innovative interventions are recommended to alleviate blindness and visual impairments especially regarding the backlog of blinding cataract, management of non-communicative, chronic, age-related eye diseases such as glaucoma, age-related macular degeneration, and diabetic retinopathy, prevention of childhood blindness, and establishment of a robust eye health information system.

Ocular infections in sub-Saharan Africa in the context of high HIV prevalence

Healthy eyes and good vision are important determinants of populations' health across the globe. Sub-Saharan Africa is affected by simultaneous epidemics of ocular infections and human immunodeficiency virus (HIV). Ocular infection and its complications, along with cataract and ocular trauma, are common conditions in this region with great impact on daily life. In this review, we discuss the epidemiology, clinical manifestations and microbial aetiology of the most important infectious ocular conditions in sub-Saharan Africa: conjunctivitis, keratitis and uveitis. We focus specifically on the potential association of these infections with HIV infection, including immune recovery uveitis. Finally, challenges and opportunities for clinical management are discussed, and recommendations made to improve care in this neglected but very important clinical field.

Blindness and cataract surgical services in Atsinanana region, Madagascar

Purpose:

To assess the prevalence and causes of avoidable blindness in Atsinanana Region, Madagascar, with the Rapid Assessment of Avoidable Blindness (RAAB) survey. We analyzed the hospital records to supplement the findings for public health care planning.

Materials and Methods:

Only villages within a two-hour walk from a road, about half of the population of Atsinanana was included. Seventy-two villages were selected by population-proportional-to-size sampling. In each village, compact segment sampling was used to select 50 people over age 50 for eye examination using standard RAAB methods. Records at the two hospitals providing cataract surgery in the region were analyzed for information on patients who underwent cataract surgery in 2010. Cataract incidence rate and target cataract surgery rate (CSR) was modeled from age-specific prevalence of cataract.

Results:

The participation rate was 87% and the sample prevalence of blindness was 1.96%. Cataract was responsible for 64% and 85.7% of blindness and severe visual impairment, respectively. Visual impairment was due to cataract (69.4%) and refractive error (14.1%). There was a strong positive correlation between cataract surgical rate by district and the proportion of people living within 2 hours of a road. There were marked differences in the profiles of the cataract patients at the two facilities. The estimated incidence of cataract at the 6/18 level was 2.4 eyes per 100 people over age 50 per year.

Conclusions:

Although the survey included only people with reasonable access, the main cause of visual impairment was still cataract. The incidence of cataract is such that it ought to be possible to eliminate it as a cause of visual impairment, but changes in service delivery at hospitals and strategies to improve access will be necessary for this change.

Change-readiness of the blind: a hospital based study in a coastal town of South India

Purpose:

Blindness is a devastating condition with psychosocial and economic effects. The shortcomings result in a burden to the blind person, the family and society. Rehabilitation of the blind can transform their lives. The aim of this study was to assess the “change-readiness” of the blind to undergo a “change-management”.

Materials and Methods:

The study was a semi-structured pre-tested questionnaire-based study of 50 blind subjects in a medical college hospital. The blind participants were assessed for depression using the Beck Depression Inventory II, for the perceived effect of blindness on family, social life and occupation. The participants were counseled to undergo psychiatric management, vocational training, use blind aids and learn Braille. The willingness of the participants with reasons was assessed using a verbal analogue scale. Pearson Chi-square test, ANOVA and the t-test were used for statistical analysis.

Results:

Over two-thirds of the subjects were depressed. Family life, social life and occupation were perceived to be affected by 44%, 66% and 74%, respectively. Change-readiness scores were low for low vision and blind aids, vocational training, psychiatric management, change of job and learning Braille. The low score was due to the associated taboo, dependence, lack of skills, embarrassment, etc., The most valuable feature was the family cohesiveness.

Conclusion:

The results suggest that there is a need to modify health policy to include blind rehabilitation, to improve visibility of blind rehabilitation centers, to include family members and co-professionals while managing the blind so that we treat the “blind person” and not a “pair of blind eyes”.

Posterior segment eye disease in sub-Saharan Africa: review of recent population-based studies

Objective

To assess the burden of posterior segment eye diseases (PSEDs) in sub-Saharan Africa (SSA).

Methods

We reviewed published population-based data from SSA and other relevant populations on the leading PSED, specifically glaucoma, diabetic retinopathy and age-related macular degeneration, as causes of blindness and visual impairment in adults. Data were extracted from population-based studies conducted in SSA and elsewhere where relevant.

Results

PSEDs, when grouped or as individual diseases, are a major contributor to blindness and visual impairment in SSA. PSED, grouped together, was usually the second leading cause of blindness after cataract, ranging as a proportion of blindness from 13 to 37%.

Conclusions

PSEDs are likely to grow in importance as causes of visual impairment and blindness in SSA in the coming years as populations grow, age and become more urban in lifestyle. African-based cohort studies are required to help estimate present and future needs and plan services to prevent avoidable blindness.

Cataract incidence in sub-Saharan Africa: what does mathematical modeling tell us about geographic variations and surgical needs?

PURPOSE

To apply a previously described mathematical model, designed to estimate cataract incidence from age-specific prevalence, to Rapid Assess of Avoidable Blindness survey data from Sub-Saharan Africa in order to estimate the incidence of cataract and therefore surgical needs.

METHODS

All Rapid Assessment of Avoidable Blindness surveys from Sub-Saharan Africa were identified. A previously developed mathematical model, designed to estimate the incidence of operable cataract was applied to those (27/32) meeting the inclusion criteria.

RESULTS

Incidence varied significantly across the continent with the result that cataract surgery rate targets required to eliminate cataract vary too. When variation in age structure is also taken into account, the cataract surgery rate needed to eliminate cataract visual impairment at the level of 6/18 ranges from 1200-4500 surgeries per year per million population.

CONCLUSIONS

This is important evidence of significant variation in the incidence of cataract within Sub-Saharan Africa. The variation may be related to genetic or cultural variations on the continent and has important implications for planning services.

An increase in phosphorylation and truncation of crystallin with the progression of cataracts

Background

Cataracts are the leading cause of blindness worldwide; however, there is no evidence regarding the direct formation of cataracts. At present, there is no treatment method other than surgery to prevent the formation or progression of cataracts.

Objective

Understanding the protein changes during various stages of cataracts might help realize the mechanism of the formation and progression of cataracts.

Methods

Lens materials were collected from cataract surgery. Cataracts were classified according to lens opacity using the gradation of the Lens Opacities Classification System. Lens proteins were separated by 2-dimensional polyacrylamide gel electrophoresis. Protein spots were visualized by Coomassie blue staining, and expression patterns were analyzed. Protein spots of interest were excised from 2-dimensional polyacrylamide gel electrophoresis gels, digested in situ with trypsin, and analyzed by mass spectrometry and liquid chromatographic tandem mass spectrometry.

Results

Crystallin was the major protein in the cataract lens, and αA, βB1, αB, and βA4 were the dominant types. Crystallin αB and βA4 increased with the formation of lens opacity. Moreover, phosphorylation and truncation of these proteins increased with the progression of cataracts.

Conclusion

Crystallin αB and βA4 and phosphorylation and truncation of crystallin in the lens might contribute to the formation of cataracts. In contrast, acetylation was not dominant in the progression of cataracts and did not play major role in the formation of cataracts.

Rapid assessment of avoidable blindness in Bhutan

AIM

To conduct a rapid assessment of avoidable blindness survey in Bhutan to obtain estimates of blindness, visual impairment, and cataract surgical coverage, outcomes and barriers among persons ≥50 years old.

METHODS

A total of 82 clusters of 50 people ≥50 years were selected using probability proportionate to size sampling. Eligible participants were selected from households using compact segment sampling, and underwent ophthalmic examination for visual acuity, followed by penlight and direct ophthalmoscopy. Participants with cataract were interviewed regarding surgical outcomes and barriers to surgery.

RESULTS

Overall, 4046 of 4100 persons enumerated (98.7%) underwent ophthalmic examination. Adjusting for age and sex, the prevalence of bilaterally blind persons with available correction was 1.5% (95% confidence interval 1.09-1.89). Most blindness (67.1%) and severe visual impairment (74.1%) resulted from cataract, but 22.1% resulted from posterior segment pathology. Cataract surgical coverage for bilaterally blind persons was 72.7%. Almost 90% of patients reported moderate or good satisfaction, despite poor surgical outcomes in 23.6%.

CONCLUSIONS

The prevalence of blindness in people aged ≥50 years in Bhutan was relatively low when compared with neighboring countries and World Health Organization sub-region estimates. Areas for improvement include community outreach, surgical outcomes, and posterior segment diseases.

Blindness and visual impairment due to age-related cataract in sub-Saharan Africa: a systematic review of recent population-based studies

AIM

We aimed to evaluate age-related cataract as a contributor to blindness and visual impairment (VI) in sub-Saharan Africa (SSA).

METHODS

A systematic review of population-based studies published between 2000 and October 2012. Prevalence and proportions of blindness and VI due to cataract, cataract surgical coverage (CSC), per cent intraocular lens (IOL) implantation and visual outcomes of surgery in accordance with WHO criteria were ascertained.

RESULTS

Data from 17 surveys (subjects mostly aged ≥ 50-years-old) from 15 different countries in SSA were included, comprising 96 402 people. Prevalence of blindness (presenting visual acuity <3/60 in better eye) ranged from 0.1% in Uganda to 9.0% in Eritrea, and the proportion of total blindness due to cataract ranged between 21% and 67%. Cataract was the principal cause of blindness and VI in 15 and 14 studies, respectively. There was a strong positive correlation between good visual outcomes and IOL use (R=0.69, p=0.027). Considerable inter-study heterogeneity was evident in CSC and visual outcomes following surgery, and between 40% and 100% of operations had used IOL.

CONCLUSIONS

Cataract represents the principal cause of blindness and VI and should remain a priority objective for eye care in SSA. However, the prevalence of blindness and VI due to cataract was variable and may reflect differences in the availability of cataract surgical programmes and cataract incidence.

Prevalence and risk factors for eye diseases, blindness, and low vision in Lhasa, Tibet

AIM

To determine the prevalence and risk factors for eye diseases, blindness, and low vision in Tibet, and to assist the development of eye disease prevention and treatment schemes.

METHODS

We carried out a survey of eye diseases among a population living at high altitude. A total of 1 115 Tibetan permanent residents aged 40 years or older from the towns and villages of Qushui County, Lhasa Prefecture, Tibet Autonomous Region, participated in this study. All participants completed a detailed questionnaire, and underwent presenting and pinhole visual acuity tests, and a comprehensive ophthalmic examination.

RESULTS

There were 187 blind eyes (8.43%), 231 eyes with low vision (10.41%). The leading cause of visual impairment was cataract of 55.0% (101/187) blindness and of 50.2% (116/231) low vision, followed by fundus lesions of 22.9% blindness and 23.8% low vision, while only a low prevalence of glaucoma of 9.6% blindness and 1.7% low vision was observed. The analysis of 2 219 eyes showed that the most common external eye disease was pterygium (27.2%) in Tibet.

CONCLUSION

The high prevalence of blindness and low vision in the Tibetan population at high altitude is a serious public health issue. There is a need to establish and maintain an appropriate effective eye care program in Tibet.

Rapid assessment methods in eye care: an overview

Reliable information is required for the planning and management of eye care services. While classical research methods provide reliable estimates, they are prohibitively expensive and resource intensive. Rapid assessment (RA) methods are indispensable tools in situations where data are needed quickly and where time- or cost-related factors prohibit the use of classical epidemiological surveys. These methods have been developed and field tested, and can be applied across almost the entire gamut of health care. The 1990s witnessed the emergence of RA methods in eye care for cataract, onchocerciasis, and trachoma and, more recently, the main causes of avoidable blindness and visual impairment. The important features of RA methods include the use of local resources, simplified sampling methodology, and a simple examination protocol/data collection method that can be performed by locally available personnel. The analysis is quick and easy to interpret. The entire process is inexpensive, so the survey may be repeated once every 5–10 years to assess the changing trends in disease burden. RA survey methods are typically linked with an intervention. This article provides an overview of the RA methods commonly used in eye care, and emphasizes the selection of appropriate methods based on the local need and context.

Assessment of avoidable blindness using the rapid assessment of avoidable blindness methodology

Background:

More than 90% of visual impairment can either be treated or avoided. Rapid Assessment of Avoidable Blindness methodology provides valid estimates in short time to assess magnitude and causes of blindness.

Aims:

To estimate the prevalence and causes of blindness in persons above 50 years in Kolar, South India, using the above methodology.

Materials and Methods:

Sixty one clusters of 50 people aged above 50 years were selected by probability-proportionate to size sampling. Participants were evaluated using a standardized survey form. Persons with vision <20/60 were dilated and examined by an ophthalmologist.

Results:

Of the 3050 people listed 2907 were examined (95.3%). Prevalence of bilateral blindness in persons was 3.9%; severe visual impairment 3.5%, and visual impairment 10.4%. Untreated cataract was the leading cause of blindness (74.6%) and severe visual impairment (73.3%). Avoidable causes of blindness accounted for 91.2% of all blindness and 95.0% of severe visual impairment. ‘Waiting for maturity’ and ‘No one to accompany’ were the most common barriers to uptake of cataract surgery.

Conclusion:

Untreated cataract continues to be the leading cause of avoidable blindness. Modified strategies need to be implemented to tackle the burden of cataract blindness.

Rapid assessment of avoidable blindness in two northern provinces of Burundi without eye services

PURPOSE

To determine the prevalence and causes of blindness, severe visual impairment and visual impairment as well as cataract surgical coverage in two northern provinces of Burundi for the purpose of planning eye services.

METHODS

The population-based Rapid Assessment of Avoidable Blindness survey methodology was used.

RESULTS

Of 3800 people enrolled, 3684 (97%) were examined. The sample prevalences of blindness, severe visual impairment, and visual impairment were 1.1% (95% confidence interval, CI 0.8-1.4), 0.6% (95% CI 0.4-0.9), and 1.7% (95% CI 1.3-2.1), respectively. The leading causes of blindness were cataract (55%) and posterior segment causes (37%). Severe visual impairment was mainly due to cataract (43%) and refractive error (39%), and visual impairment was mainly due to refractive error (67%) and cataract (18%). Cataract surgical coverage by person at the level of <6/60 was 15%.

CONCLUSIONS

The low prevalence of vision loss in this area with no eye services and a low cataract surgical coverage rate is surprising and possibly due to the effects of the previous years of conflict in which those with decreased vision may have been most likely to perish. If this explanation is correct, then Burundi needs to plan to deal with a markedly increasing prevalence of cataract in future.

Future trends in global blindness

The objective of this review is to discuss the available data on the prevalence and causes of global blindness, and some of the associated trends and limitations seen. A literature search was conducted using the terms "global AND blindness" and "global AND vision AND impairment", resulting in seven appropriate articles for this review. Since 1990 the estimate of global prevalence of blindness has gradually decreased when considering the best corrected visual acuity definition: 0.71% in 1990, 0.59% in 2002, and 0.55% in 2010, corresponding to a 0.73% reduction per year over the 2002-2010 period. Significant limitations were found in the comparability between the global estimates in prevalence or causes of blindness or visual impairment. These limitations arise from various factors such as uncertainties about the true cause of the impairment, the use of different definitions and methods, and the absence of data from a number of geographical areas, leading to various extrapolation methods, which in turn seriously limit comparability. Seminal to this discussion on limitations in the comparability of studies and data, is that blindness has historically been defined using best corrected visual acuity.

The Nakuru posterior segment eye disease study: methods and prevalence of blindness and visual impairment in Nakuru, Kenya

OBJECTIVES

To estimate the prevalence of blindness and visual impairment (VI) in adults aged ≥50 years in the Nakuru district of Kenya and to identify sociodemographic risk factors for these conditions. We also sought to validate the Rapid Assessment of Avoidable Blindness (RAAB) methodology.

PARTICIPANTS

There were 5010 subjects enumerated for this study. Of these, 4414 participants underwent examination, for a response rate of 88.1%.

DESIGN

Cross-sectional, population-based survey.

METHODS

Cluster random samplings with probability proportionate to size procedures were used to select a representative cross-sectional sample of adults aged ≥50 years. Each participant was interviewed, had distance visual acuity (VA) measured with reduced logarithm of the minimal angle of resolution tumbling-E chart, underwent autorefraction, and thereby had measurements of presenting, uncorrected, and best-corrected VA. All participants, regardless of vision, underwent detailed ophthalmic examinations including slit-lamp assessment and dilated retinal photographs.

MAIN OUTCOME MEASURES

Visual acuity of <6/12.

RESULTS

A representative sample of 4414 adults were enumerated (response rate, 88.1%). The prevalence of blindness (VA < 3/60 in better eye) was 1.6% (95% confidence interval [CI], 1.2-2.1%) and of VI, 0.4% (95% CI, 0.3-0.7%); 8.1% (95% CI, 7.2-9.2%); and 5.1% (95% CI, 4.3-6.1%) were severely (<6/60-3/60), moderately (<6/18-6/60), or mildly (<6/12-6/18) visually impaired, respectively. Being male, having less education, having Kalenjin tribal origin, and being ≥80 years old were associated with increased blindness prevalence. Prevalence estimates were comparable to a RAAB performed in the same area 2 years earlier.

CONCLUSIONS

This survey provides reliable estimates of blindness and VI prevalence in Nakuru. Older age and tribal origin were identified as predictors of these conditions. This survey validates the use of RAAB as a method of estimating blindness and VI prevalence.

Serum autoantibody biomarkers for age-related macular degeneration and possible regulators of neovascularization

Age-related macular degeneration (AMD) is the leading cause of irreversible blindness in industrial counties. Its pathogenesis is at least partially mediated by immunological factors, including a possible autoimmune response. To date, only a few antibodies have been identified in sera from patients with AMD. In order to reveal an autoantibody profile for AMD and identify biomarkers for progression of this disease, we have performed an antigen microarray analysis of serum samples from patients with AMD and healthy controls. Sera from the AMD groups contained high levels of IgG and IgM autoantibodies to some systemic antigens when compared to the normal group. Targeted antigens included cyclic nucleotide phosphodiesterase, phosphatidylserine (PS) and proliferating cell nuclear antigen. The IgG/IgM ratio for antibodies to PS was notably elevated in the AMD group compared to the normal group, and this ratio correlated best with the stage of AMD patients with an anti-PS ratio greater than the cut-off value had a 44-fold risk for advanced AMD with choroidal neovascularization. PS immunoreactivity was also elevated in AMD retina. Moreover, IgG autoantibodies purified from sera of AMD patients induced more tube formation on choroidal-retinal endothelial cells compared to those of healthy donors. Hence, sera from patients with AMD contain specific autoantibodies which may be used as biomarkers for AMD, and the IgG/M ratio for autoantibodies to PS might allow better monitoring of AMD progression.

Rapid assessment of visual impairment (RAVI) in marine fishing communities in South India--study protocol and main findings

Background

Reliable data are a pre-requisite for planning eye care services. Though conventional cross sectional studies provide reliable information, they are resource intensive. A novel rapid assessment method was used to investigate the prevalence and causes of visual impairment and presbyopia in subjects aged 40 years and older. This paper describes the detailed methodology and study procedures of Rapid Assessment of Visual Impairment (RAVI) project.

Methods

A population-based cross-sectional study was conducted using cluster random sampling in the coastal region of Prakasam district of Andhra Pradesh in India, predominantly inhabited by fishing communities. Unaided, aided and pinhole visual acuity (VA) was assessed using a Snellen chart at a distance of 6 meters. The VA was re-assessed using a pinhole, if VA was < 6/12 in either eye. Near vision was assessed using N notation chart binocularly. Visual impairment was defined as presenting VA < 6/18 in the better eye. Presbyopia is defined as binocular near vision worse than N8 in subjects with binocular distance VA of 6/18 or better.

Results

The data collection was completed in <12 weeks using two teams each consisting of one paramedical ophthalmic personnel and two community eye health workers. The prevalence of visual impairment was 30% (95% CI, 27.6-32.2). This included 111 (7.1%; 95% CI, 5.8-8.4) individuals with blindness. Cataract was the leading cause of visual impairment followed by uncorrected refractive errors. The prevalence of blindness according to WHO definition (presenting VA < 3/60 in the better eye) was 2.7% (95% CI, 1.9-3.5).

Conclusion

There is a high prevalence of visual impairment in marine fishing communities in Prakasam district in India. The data from this rapid assessment survey can now be used as a baseline to start eye care services in this region. The rapid assessment methodology (RAVI) reported in this paper is robust, quick and has the potential to be replicated in other areas.