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.

Current Management of Retinopathy of Prematurity

Purpose of Review
This review aims to provide an update on the recent major advances in the management of retinopathy of prematurity (ROP).

Recent Findings
There have been a number of major advances in our understanding and management of ROP over the last decade: (1) The advent of improved imaging techniques and technological infrastructure has led to the increased use of telemedicine and potential use of artificial intelligence to enhance access to care for children at risk of developing ROP; (2) the International Classification of Retinopathy of Prematurity (ICROP) 3rd edition has provided updates in classification of ROP and response of ROP to treatment; and (3) the treatment paradigm has shifted from laser therapy exclusively to now having the option of anti-vascular endothelial growth factor (VEGF) therapy. This has led to greater interest in trying to better understand the possible adverse events related to systemic and local VEGF suppression.

Summary
There is a greater understanding in the diagnosis and treatment of ROP and its response to treatment. The advent of anti-VEGF therapy has provided ROP providers with a treatment modality that may lead to improved visual outcomes without the need for peripheral retinal ablation. However, there remain questions regarding systemic and local adverse events. Laser photocoagulation continues to be an effective primary therapy and may also be needed after or in conjunction with anti-VEGF treatment.

Early treatment of corneal abrasions and ulcers–estimating clinical and economic outcomes

Background
In low-and-middle income countries, corneal abrasions and ulcers are common and not always well managed. Previous studies showed better clinical outcomes with early presentation and treatment of minor abrasions, however, there have been no formal studies estimating the financial impact of early treatment of abrasions and ulcers compared to delayed treatment.

Methods
We used the LV Prasad Eye Institute’s (LVPEI’s) electronic health record system (eyeSmart) to estimate the impact of early presentation on clinical outcomes associated with abrasions and ulcers. 861 patients with corneal abrasion and 1821 patients with corneal ulcers were studied retrospectively, and 134 patients with corneal abrasion prospectively. A health economic model was constructed based on LVPEI cost data for a range of patient scenarios (from early presentation with abrasion to late presentation with ulcer).

Findings
Our findings suggest that delayed presentation of corneal abrasion results in poor clinical and economic outcomes due to increased risk of ulceration requiring more extensive surgical management, increasing associated costs to patients and the healthcare system. However, excellent results at low cost can be achieved by treatment of patients with early presentation of abrasions at village level health care centres.

Interpretation
Treatment of early minor corneal abrasions, particularly using local delivery of treatment, is effective clinically and economically. Future investment in making patients aware of the need to react promptly to corneal abrasions by accessing local healthcare resources (coupled with a campaign to prevent ulcerations occurring) will continue to improve clinical outcomes for patients at low cost and avoid complex and more expensive treatment to preserve sight.

Funding
This research was funded by the Medical Research Council, grant MR/S004688/1.

Evaluation of an Artificial Intelligence System for Retinopathy of Prematurity Screening in Nepal and Mongolia

Objective
The purpose of this study is to evaluate the performance of a deep learning algorithm for retinopathy of prematurity (ROP) screening in Nepal and Mongolia.

Design
This was a retrospective analysis of prospectively collected clinical data.

Subjects
Clinical information and fundus images were obtained from infants in two ROP screening programs in Nepal and Mongolia.

Methods
Fundus images were obtained using the Forus 3nethra neo in Nepal and RetCam® Portable in Mongolia. The overall severity of ROP was determined from the medical record using the International Classification of ROP (ICROP). The presence of plus disease was independently determined in each image using a reference standard diagnosis. The Imaging and Informatics for ROP (i-ROP) deep learning (DL) algorithm, which was trained on images from the RetCam® was used to classify plus disease, as well as assign a vascular severity score (VSS) from 1-9.

Main outcome measures
The main outcome measures were area under the receiver operating characteristic (AUC-ROC) and area under the precision recall curve (AUC-PR) for the presence of plus disease or type 1 ROP, and association between VSS and ICROP disease category.

Results
The prevalence of type 1 ROP was found to be higher in Mongolia (14.0%) than in Nepal (2.2%, p < 0.001) in these data sets. In Mongolia (Retcam images), the AUC-ROC for exam-level plus disease detection was 0.968 and AUC-PR was 0.823. In Nepal (Forus images), the AUC-ROC for exam-level plus disease detection was 0.999 and AUC-PR was 0.993. The ROP vascular severity score was associated with ICROP classification in both datasets (p < 0.001). At the population level, the median [interquartile range] VSS was found to be higher in Mongolia (2.7 [1.3–5.4]) as compared to Nepal (1.9 [1.2–3.4], p < 0.001). Conclusions These data provide preliminary evidence of the effectiveness of the i-ROP DL algorithm for ROP screening in neonatal populations in Nepal and Mongolia, using multiple camera systems, and provide useful data for consideration in future clinical implementation of AI-based ROP screening in low- and middle-income countries.

Vision impairment and self-reported anxiety and depression in older adults in Nigeria: evidence from a cross-sectional survey in Kogi State

Background
More than 2 billion people are thought to be living with some form of vision impairment worldwide. Yet relatively little is known about the wider impacts of vision loss on individual health and well-being, particularly in low- and middle-income countries (LMICs). This study estimated the associations between all-cause vision impairment and self-reported symptoms of anxiety and depression among older adults in Kogi State, Nigeria.

Methods
Individual eyes were examined according to the standard Rapid Assessment of Avoidable Blindness methodology, and anxiety and depression were assessed using the Washington Group Short Set on Functioning–Enhanced. The associations were estimated using multivariable logistic regression models, adding two- and three-way interaction terms to test whether these differed for gender subgroups and with age.

Results
Overall, symptoms of either anxiety or depression, or both, were worse among people with severe visual impairment or blindness compared with those with no impairment (OR=2.72, 95% CI 1.86 to 3.99). Higher levels of anxiety and/or depression were observed among men with severe visual impairment and blindness compared with women, and this gender gap appeared to widen as people got older.

Conclusions
These findings suggest a substantial mental health burden among people with vision impairment in LMICs, particularly older men, underscoring the importance of targeted policies and programmes addressing the preventable causes of vision impairment and blindness.

Piloting targeted glaucoma screening: experiences of eye care services in Ganjam district, Odisha state, India

Background
The number of patients with visual impairment and blindness from glaucoma is rapidly increasing with wide-ranging impacts for individuals and societies. However, the disease often goes undiagnosed for a long time, especially in low- and middle-income countries where healthcare services are limited. This paper presents the results of a pilot programme, which integrated targeted glaucoma screenings of people aged ≥40 y in community-based eye care services in the Ganjam district of Odisha state, India.

Methods
Using routine programme data, descriptive statistics were produced for the characteristics of patients participating in the screening programme and the rate and uptake of glaucoma referrals. Bivariate analysis was used to examine associations between patient characteristics, clinical risk factors and glaucoma diagnosis.

Results
Out of 23 356 individuals aged ≥40 y screened for glaucoma over a period of 18 mo, 2219 (9.5%) were referred and 2031 presented for further examination. Among them, almost half (n=968, 48%) were diagnosed with glaucoma, representing a screening to diagnosis conversion rate of 4.14% (95% CI 3.9 to 4.4%). A positive diagnosis of glaucoma among suspects was associated with female sex, age >60 y, visual impairment, vertical cap-to-disc ratio ≥0.6:1, intraocular pressure ≥30 mmHg and shallow anterior chamber (p<0.001).

Conclusions
The importance of targeted screening for glaucoma using simple referral criteria to identify patients at high risk of vision loss who can benefit from treatment is critical to slow the progression of the disease and the prevention of blindness. Further studies assessing costs of the targeted screening, the role of technology in improving programme effectiveness and efficiency and the longer term compliance with treatment are needed to support glaucoma policy frameworks, guidelines and clinical practice.

Real-world visual outcomes of cataract surgery based on population-based studies: a systematic review

Background/aims Quantity of cataract surgery has long been an important public health indicator to assess health accessibility, however the quality of care has been less investigated. We aimed to summarise the up-to-date evidences to assess the real-world visual outcomes after cataract surgery in different settings.

Methods A systematic review was undertaken in October 2021. Population-based cross-sectional and longitudinal studies reporting vision-related outcomes after cataract surgery published from 2006 onward were included. A meta-analysis was not planned.

Results Twenty-six cross-sectional studies from low-income and middle-income countries (LMICs) and five cross-sectional studies from high-income countries (HICs) were included. The proportions of participants with postoperative presenting visual acuity (VA) ≥0.32 (20/60) were all over 70% in all HICS studies, but mostly below 70% in LMICS studies, ranging from 29.9% to 80.5%. Significant difference in postoperative VA was also observed within countries. The leading causes for postoperative visual impairment (defined mostly as presenting VA <20/60) mainly included refractive error, ocular comorbidities and surgical complications including posterior capsule opacification, except for one study in Nigeria wherein the leading cause was aphakia. Only four population-based cohort studies were included with 5–20 years of follow-up time, generally demonstrating no significant changes in postoperative visual outcomes during the follow-up.

Conclusions We observed large inequality in the visual outcomes and principal causes of visual impairment after cataract surgery among different countries and regions. Structured quality control and enhancement programmes are needed to improve the outcomes of cataract surgery and reduce inequality.

Advancing eye health within universal health coverage: the role of programmatic data and implementation research

In the past 3 y, considerable attention has been paid to the importance of eye health as a global development priority, first by the World Report on Vision launched by the World Health Organization (WHO) in October 2019,1 then by the Lancet Global Health Commission on Global Eye Health, published in February 20212 and most recently by the Vision for Everyone Resolution adopted by the United Nations (UN) General Assembly in July 2021.3 All three documents provide compelling evidence on the magnitude, impact and costs of poor vision and call for coordinated global efforts to improve access to and the quality and equity of eye care services worldwide. The documents argue that the progress towards the Sustainable Development Goals (SDGs)4 will not be sufficient without integrating eye health within universal health coverage (UHC)5 and highlight the role of quality evidence and research in achieving this ambitious global agenda. The Lancet Global Health Commission gives particular attention to contextually relevant solution-focused implementation research and to translating research findings into policy and practice.2

International non-governmental organisations (iNGOs) have been at the forefront of the global efforts to eliminate avoidable vision impairment and improve access to eye care services in low- and middle-income countries (LMICs) for several decades. Their role in mobilising resources, service delivery, building local capacity and advocacy has been well recognised. In recent years, a number of iNGOs have made considerable investments in generating high-quality evidence and have become important players in eye health implementation research.

There are a number of critical strengths that iNGOs bring to international research. First, iNGOs have a good understanding of service delivery realities and frontline knowledge gaps and can help identify research questions that fit local priorities and meet the needs of local governments, healthcare providers and communities. Second, integrating implementation research into ongoing programmatic activities is both practical and cost-effective. Third, iNGOs are closely engaged with national and local decision-making processes and are well positioned to facilitate the uptake and use of research findings.

This special issue clearly illustrates how iNGOs can contribute to generating crucial evidence to answer operational questions they face and to advance global knowledge on eye health. We are delighted to introduce a collection of articles that present evidence from secondary data analysis and implementation research integrated into eye health programmes supported by the iNGO Sightsavers in sub-Saharan Africa and Asia. This is the first of three supplements to be led by Sightsavers in 2022 and 2023. The two later supplements will focus specifically on evidence from our neglected tropical diseases (NTDs) programmes. In this supplement, we present research findings on a range of eye conditions, including cataracts, unaddressed refractive error (URE), glaucoma, trachoma and onchocerciasis. The articles draw on evidence from 12 countries and address a number of topics pertinent to eye health policies and services in LMICs. We are particularly pleased that several articles are based on a secondary analysis of our programmatic data and have been authored by the technical experts and managers supporting our programmes in the field.

The supplement opens with a guest editorial by Keel and Cieza of the WHO, who present the recent UN developments in support of eye health and highlight global priorities for action to facilitate the journey of member states towards universal eye health. The key messages of the guest editorial are echoed in the commentary by Jones, who discusses the state of eye health funding in LMICs and calls for a step change in delivering more and better financing for eye health within UHC.

The substantial impact of vision on other global health priorities is highlighted in the article by Gascoyne et al., who included disability metrics in a visual impairment survey in Kogi State in Nigeria and present new evidence on the intersection of vision impairment and mental health.

In recognition of the multiple health priorities facing populations in LMICs and the finite resources to address them, a number of articles explore questions on how to make the right policy choices and maximise the effectiveness and efficiency of eye care delivery. Hamill et al. report on the results of a pilot study assessing the feasibility and affordability of mapping areas with medium to low transmission of onchocerciasis in Ghana and Nigeria. They argue that as more and more countries approach onchocerciasis elimination thresholds, questions regarding the cost-effectiveness of treatment in hypo-endemic areas become more and more pressing and the role of implementation research generating such evidence should not be underestimated.

Another article in the series addresses questions of efficiency and equity of services in the context of trachoma elimination. Ul Hassan et al. use programmatic data from seven trachoma-endemic countries (Ethiopia, Kenya, Mozambique, Zambia, Tanzania, Uganda and Nigeria) and compare the effectiveness of different community mobilisation and case-finding approaches with a specific focus on gender. The article stresses the importance of routine multicountry service data in developing recommendations and guidance relevant to a variety of settings.

In India, Buttan et al. also analysed programmatic data from a pilot study that integrated targeted glaucoma screening into existing eye care services and assessed the feasibility and benefits of this approach. Glaucoma is a rapidly emerging global eye health priority that is very challenging for resource-poor settings and operational data on how to address it in a pragmatic and cost-effective way are lacking. Integrating implementation research into ongoing eye care programmes provides an excellent opportunity to build the evidence base so urgently needed by the sector.

Another global priority addressed in this supplement is developing an eye health workforce that is able to meet the growing needs for eye care globally. Two articles focus on task shifting, a strategy frequently used in eye health to address the constant shortages of eye care specialists in LMICs. In a commentary on primary eye care, Yasmin and Schmidt review lessons learned from eye care programmes in Tanzania, Sierra Leone and Pakistan. They argue that while the integration of certain eye care tasks into the roles of primary health and community workers is feasible, a system thinking approach is critical to ensure it is done in a coherent and sustainable way. Further, in a study in Liberia, Tobi et al. show that teachers can be trained to conduct vision screening of schoolchildren to an acceptable level of accuracy. However, based on the data generated by the programme, the authors warn that careful considerations should be given to teachers’ supervision and quality assurance systems.

Two further articles focus on patient-centred care, the theme that features centrally in the World Report on Vision1 and the new eye health agenda. Shrestha et al. explore characteristics and perspectives of patients with postoperative trichiasis in the Hadiya Zone of Ethiopia, while Bechange et al. report results of a multicountry qualitative study considering patients’ perspectives on cataract surgery in rural areas of Kenya, Zambia and Uganda. Both articles argue that patients’ perceptions of quality of care are important determinants of their health-seeking behaviour and need to be better understood to maximise the effectiveness and efficiency of surgical outreach.

Two remaining articles address the role of evidence and innovations in eye health. A commentary by Bartlett et al. describes Sighsavers’ experience of working with the Federal Ministry of Health of Nigeria on strengthening national electronic medical records systems and specifically the adaptation of the electronic data collection tool known as the Trachomatis Trichiasis (TT) Tracker commonly used in trachoma programmes to the needs of paediatric cataract services. Finally, Jolley et al. use the evidence gap map approach and present the current state of evidence from cataract-related systematic reviews relevant to LMICs. The authors point to the shortage of evidence on cataract-related health systems, equity and impact—the gaps also highlighted by the World Report on Vision and the Lancet Commission.

We would like to thank all the authors for the time they spent preparing the manuscripts and for sharing their valuable experiences and findings in an open and transparent way. Many thanks to our reviewers for their time and constructive comments and advice.

We are preparing this supplement at the time of the unfolding coronavirus disease 2019 pandemic. While the scale and impact of this unprecedented global crisis is yet to be fully understood, the increasing importance of evidence in decision-making is indisputable and the role of implementation research is becoming more prominent than ever before. We hope you enjoy reading these articles and find them useful in your own programmatic decisions and policy choices.

Assessing the prevalence of refractive errors and accuracy of vision screening by schoolteachers in Liberia

Background
Evidence indicates that school-based vision screening by trained teachers is an effective way of identifying and addressing potential vision problems in schoolchildren. However, inconsistencies have been reported in both the testing methods and accuracy of the screeners. This study assessed the prevalence of refractive errors and accuracy of screening by teachers in Grand Kru County, Liberia.

Methods
We conducted a retrospective analysis of data from four schools where, in February 2019, children were screened for refractive errors by trained teachers and then re-examined by ophthalmic technicians. One row of five optotypes of the Snellen 6/9 (0.2 logMar) scale (tumbling E chart) was used at a distance of 3 m. The prevalence of visual impairment and associations with sex, age and school were explored. Sensitivity, specificity and predictive values were calculated.

Results
Data were available for 823 of 1095 eligible children with a mean age of 13.7 y (range 5–18) and male:female ratio of 1:0.8. Poor vision was identified in 24 (2.9%) children with no differences by either sex or age but small differences by school. Screening by teachers had a sensitivity of 0.25 (95% confidence interval [CI] 0.077 to 0.423) and a specificity of 0.996 (95% CI 0.992 to 1.000). Positive and negative predictive values were 0.667 (95% CI 0.359 to 0.975) and 0.978 (95% CI 0.968 to 0.988), respectively. The results were influenced by a high number of misclassifications in one of the four schools.

Conclusions
Teachers can be trained to conduct vision screening tests on schoolchildren to an acceptable level of accuracy, but strong monitoring and quality assurance systems should be built into screening programmes from the onset. In settings like Liberia, where many children do not attend school regularly, screening programmes should extend to community platforms to reach children out of school.

Evidence on cataract in low- and middle-income countries: an updated review of reviews using the evidence gap maps approach

In 2014, Sightsavers developed the first evidence gap map (EGM) to assess the extent and quality of review-level evidence on cataract relevant to low-and middle-income countries. The EGM identified 52 studies across five broad themes. This paper reports the update of the EGM conducted in 2021 and changes to the extent and quality of the evidence base. We updated the EGM using the exact process conducted to develop the original. Searches were run to 14 September 2021, and two independent reviewers selected eligible studies, critically appraised them and extracted data using the Supporting the Use of Research Evidence checklist. A summary quality assessment was shared with the authors for comments. Forty-six new reviews were identified, and the EGM now includes 98 reviews. The new reviews predominantly focus on treatment and risk factors. The overall methodological quality was found to be improved, with 13/46 reporting high confidence in findings. EGMs remain a useful tool for policy-makers to make informed decisions and periodic updates are important to assess changes and to refine the focus for future research. The EGM highlights significant disparity in the topics addressed by reviews, with health system interventions particularly neglected.