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

Prevalence and causes of blindness and visual impairment in Kogi state, Nigeria-Findings from a Rapid assessment of avoidable blindness survey

PURPOSE

To determine the prevalence and causes of blindness and visual impairment among adults in Kogi, Nigeria.

METHODS

A Rapid assessment of avoidable blindness (RAAB) protocol was used with additional tools measuring disability and household wealth to measure the prevalence of blindness and visual impairment (VI) and associations with sex, disability, wealth, cataract surgical coverage and its effectiveness.

RESULTS

Age- and sex-adjusted all-cause prevalence of bilateral blindness was 3.6% (95%CI 3.0-4.2%), prevalence of blindness among people living with additional, non-visual disabilities was 38.3% (95% CI 29.0-48.6%) compared to 1.6% (95%CI 1.2-2.1%; [Formula: see text] = 771.9, p<0.001) among people without additional disabilities. Cataract was the principal cause of bilateral blindness (55.3%). Cataract surgical coverage (CSC) at visual acuity (VA) 3/60 was 48.0%, higher among men than women (53.7% vs 40.3%); 12.0% among people with non-visual disabilities; 66.9% among people without non-visual disabilities, being higher among people in the wealthiest two quintiles (41.1%) compared to the lowest three (24.3%). Effective Cataract Surgical Coverage at Visual Acuity 6/60 was 31.0%, higher among males (34.9%) than females (25.5%), low among people with additional, non-visual disabilities (1.9%) compared to people with no additional disabilities (46.2%). Effective CDC was higher among people in the wealthiest two quintiles (411%) compared to the poorest three (24.3%). Good surgical outcome (VA>6/18) was seen in 61 eyes (52.6%) increasing to 71 (61.2%) eyes with best correction. Cost was identified as the main barrier to surgery.

CONCLUSION

Findings suggest there exists inequalities in eye care with women, poorer people and people with disabilities having a lower Cataract Surgical Coverage, thereby, underscoring the importance of eye care programs to address these inequalities.

Travel time to cataract surgical services in Kenya, Malawi and Rwanda: demonstrating a standardised indicator of physical access to cataract surgery

BACKGROUND

Travel time can be used to assess health services accessibility by reflecting the proximity of services to the people they serve. We aimed to demonstrate an indicator of physical access to cataract surgery and identify subnational locations where people were more at risk of not accessing cataract surgery.

METHODS

We used an open-access inventory of public health facilities plus key informants in Kenya, Malawi and Rwanda to compile a geocoded inventory of cataract facilities. For each country, gridded estimates of the population aged ≥ 50 years and a travel-time friction surface were combined and a least-cost-path algorithm applied to estimate the shortest travel time between each grid and the nearest cataract facility. We categorised continuous travel time by 1-, 2- and 3 h thresholds and calculated the proportion of the population in each category.

RESULTS

At the national level, the proportion of the population aged ≥ 50 years within 2 h travel time to permanent cataract surgical services was 97.2% in Rwanda (n = 10 facilities), 93.5% in Kenya (n = 74 facilities) and 92.0% in Malawi (n = 6 facilities); this reduced to 77.5%, 84.1% and 52.4% within 1 h, respectively. The least densely populated subnational regions had the poorest access to cataract facilities in Malawi (0.0%) and Kenya (1.9%).

CONCLUSION

We demonstrated an indicator of access that reflects the distribution of the population at risk of age-related cataract and identifies regions that could benefit from more accessible services. This indicator provides additional demand-side context for eye health planning and supports WHO's goal of advancing integrated people-centred eye care.

Sociodemographic disparities in ophthalmological clinical trials

Introduction

In ophthalmology, clinical trials (CTs) guide the treatment of diseases such as diabetic retinopathy, myopia, age-related macular degeneration, glaucoma and keratoconus with distinct presentations, pathological characteristics and responses to treatment in minority populations.

Reporting gender and race and ethnicity in healthcare studies is currently recommended by National Institutes of Health (NIH) and Food and Drug Administration (FDA) guidelines to ensure representativeness and generalisability; however, CT results that include this information have been limited in the past 30 years.

The objective of this review is to analyse the sociodemographic disparities in ophthalmological phases III and IV CT based on publicly available data.

Methods

This study included phases III and IV complete ophthalmological CT available from clinicaltrials.org, and describes the country distribution, race and ethnicity description and gender, and funding characteristics.

Results

After a screening process, we included 654 CTs, with findings that corroborate the previous CT reviews’ findings that most ophthalmological participants are white and from high-income countries. A description of race and ethnicity is reported in 37.1% of studies but less frequently included within the most studied ophthalmological specialty area (cornea, retina, glaucoma and cataracts). The incidence of race and ethnicity reporting has improved during the past 7 years.

Discussion

Although NIH and FDA promote guidelines to improve generalisability in healthcare studies, the inclusion of race and ethnicity in publications and diverse participants in ophthalmological CT is still limited. Actions from the research community and related stakeholders are necessary to increase representativeness and guarantee generalisability in ophthalmological research results to optimise care and reduce related healthcare disparities.

Cataract services for all: Strategies for equitable access from a global modified Delphi process

Vision loss from cataract is unequally distributed, and there is very little evidence on how to overcome this inequity. This project aimed to engage multiple stakeholder groups to identify and prioritise (1) delivery strategies that improve access to cataract services for under-served groups and (2) population groups to target with these strategies across world regions. We recruited panellists knowledgeable about cataract services from eight world regions to complete a two-round online modified Delphi process. In Round 1, panellists answered open-ended questions about strategies to improve access to screening and surgery for cataract, and which population groups to target with these strategies. In Round 2, panellists ranked the strategies and groups to arrive at the final lists regionally and globally. 183 people completed both rounds (46% women). In total, 22 distinct population groups were identified. At the global level the priority groups for improving access to cataract services were people in rural/remote areas, with low socioeconomic status and low social support. South Asia and Sub-Saharan Africa were the only regions in which panellists ranked women in the top 5 priority groups. Panellists identified 16 and 19 discreet strategies to improve access to screening and surgical services, respectively. These mostly addressed health system/supply side factors, including policy, human resources, financing and service delivery. We believe these results can serve eye health decision-makers, researchers and funders as a starting point for coordinated action to improve access to cataract services, particularly among population groups who have historically been left behind.

Association of vision impairment and blindness with socioeconomic status in adults 50 years and older from Alto Amazonas, Peru

OBJECTIVE

To determine the relationship between socioeconomic status (SES) and visual impairment (VI) or blindness in the rural Peruvian Amazon, hypothesizing that higher SES would have a protective effect on the odds of VI or blindness.

METHODS

In this cross-sectional study of 16 rural communities in the Peruvian Amazon, consenting adults aged ≥ 50 years were recruited from ~30 randomly selected households per village. Each household was administered a questionnaire and had a SES score constructed using principal components analysis. Blindness and VI were determined using a ministry of health 3-meter visual acuity card.

RESULTS

Overall, 207 adults aged ≥ 50 were eligible; 146 (70.5%) completed visual acuity screening and answered the questionnaire. Of those 146 participants who completed presenting visual acuity screening, 57 (39.0%, 95% CI 30.2-47.1) were classified as visually impaired and 6 (4.1%, 95% CI 0.9-7.3) as blind. Belonging to the highest SES tercile had a protective effect on VI or blindness (OR 0.29, 95% CI 0.09 to 0.91, p = 0.034), with a linear trend across decreasing levels of SES (p = 0.019). This observed effect remained significant regardless of how SES groups were assigned.

CONCLUSION

Belonging to a higher SES group resulted in a lower odds of VI or blindness compared to those in the lowest SES group. The observation of a dose response provides confidence in the observed association, but causality remains unclear. Blindness prevention programs could maximize impact by designing activities that specifically target people with lower SES.

Strategies for cataract and uncorrected refractive error case finding in India: Costs and cost-effectiveness at scale

Background

India has the largest number of individuals suffering from visual impairment and blindness in the world. Recent surveys indicate that demand-based factors prevent more than 80% of people from seeking appropriate eye services, suggesting the need to scale up cost-effective case finding strategies. We assessed total costs and cost-effectiveness of multiple strategies to identify and encourage people to initiate corrective eye services.

Methods

Using administrative and financial data from six Indian eye health providers, we conduct a retrospective micro-costing analysis of five case finding interventions that covered 1·4 million people served at primary eye care facilities (vision centers), 330,000 children screened at school, 310,000 people screened at eye camps and 290,000 people screened via door-to-door campaigns over one year. For four interventions, we estimate total provider costs, provider costs attributable to case finding and treatment initiation for uncorrected refractive error (URE) and cataracts, and the societal cost per DALY averted. We also estimate provider costs of deploying teleophthalmology capability within vision centers. Point estimates were calculated from provided data with confidence intervals determined by varying parameters probabilistically across 10,000 Monte Carlo simulations.

Findings

Case finding and treatment initiation costs are lowest for eye camps (URE: $8·0 per case, 95% CI: 3·4-14·4; cataracts: $13·7 per case, 95% CI: 5·6-27·0) and vision centers (URE: $10·8 per case, 95% CI: 8·0-14·4; cataracts: $11·9 per case, 95% CI: 8·8-15·9). Door-to-door screening is as cost-effective for identifying and encouraging surgery for cataracts albeit with large uncertainty ($11·3 per case, 95% CI: 2·2 to 56·2), and more costly for initiating spectacles for URE ($25·8 per case, 95% CI: 24·1 to 30·7). School screening has the highest case finding and treatment initiation costs for URE ($29·3 per case, 95% CI: 15·5 to 49·6) due to the lower prevalence of eye problems in school aged children. The annualized cost of operating a vision center, excluding procurement of spectacles, is estimated at $11,707 (95% CI: 8,722-15,492). Adding teleophthalmology capability increases annualized costs by $1,271 per facility (95% CI: 181 to 3,340). Compared to baseline care, eye camps have an incremental cost-effectiveness ratio (ICER) of $143 per DALY (95% CI: 93-251). Vision centers have an ICER of $262 per DALY (95% CI: 175-431) and were able to reach substantially more patients than any other strategy.

Interpretation

Policy makers are expected to consider cost-effective case finding strategies when budgeting for eye health in India. Screening camps and vision centers are the most cost-effective strategies for identifying and encouraging individuals to undertake corrective eye services, with vision centers likely to be most cost-effective at greater scale. Investment in eye health continues to be very cost-effective in India.

Funding

The study was funded by the Seva Foundation.

Association of objective and subjective far vision impairment with perceived stress among older adults in six low- and middle-income countries

OBJECTIVES

To assess the association between far vision impairment (objective and subjective) and perceived stress among older adults from six low- and middle-income countries (LMICs, i.e., China, Ghana, India, Mexico, Russia, and South Africa).

METHODS

Data from the WHO Study on global AGEing and adult health were analyzed. Objective visual acuity was measured using the tumbling E LogMAR chart and was used as a four-category variable (no, mild, moderate, and severe visual impairment). Subjective visual impairment referred to difficulty in seeing and recognizing an object or a person across the road. Using two questions from the Perceived Stress Scale, a perceived stress variable was computed, and ranged from 0 (lowest stress) to 100 (highest stress). Multivariable linear regression with perceived stress as the outcome was conducted.

RESULTS

Data on 14,585 adults aged ≥65 years [mean (SD) age 72.6 (11.5) years; 55.0% females] were analyzed. Only severe objective visual impairment (versus no visual impairment) was significantly associated with higher levels of stress (b = 6.91; 95% CI = 0.94-12.89). In terms of subjective visual impairment, compared with no visual impairment, mild (b = 2.67; 95% CI = 0.56-4.78), moderate (b = 8.18; 95% CI = 5.84-10.52), and severe (b = 11.86; 95% CI = 9.11-14.61) visual impairment were associated with significantly higher levels of perceived stress.

CONCLUSIONS

This large study showed that far vision impairment was associated with increased perceived stress levels among older adults in LMICs. Increased availability of eye care services may reduce stress among those with visual impairment in LMICs, while more research is needed to better characterize the directionality of the far vision impairment-perceived stress relationship.

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.

Diabetic retinopathy service delivery and integration into the health system in Pakistan-Findings from a multicentre qualitative study

This paper is based on qualitative research carried out in a diabetic retinopathy (DR) programme in three districts of Pakistan. It analyses the organisation and delivery of DR services and the extent to which the interventions resulted in a fully functioning integrated approach to DR care and treatment. Between January and April 2019, we conducted 14 focus group discussions and 37 in-depth interviews with 144 purposively selected participants: patients, lady health workers (LHWs) and health professionals. Findings suggest that integration of services was helpful in the prevention and management of DR. Through the efforts of LHWs and general practitioners, diabetic patients in the community became aware of the eye health issues related to uncontrolled diabetes. However, a number of systemic pressure points in the continuum of care seem to have limited the impact of the integration. Some components of the intervention, such as a patient tracking system and reinforced interdepartmental links, show great promise and need to be sustained. The results of this study point to the need for action to ensure inclusion of DR on the list of local health departments’ priority conditions, greater provision of closer-to-community services, such as mobile clinics. Future interventions will need to consider the complexity of adding diabetic retinopathy to an already heavy workload for the LHWs.

Interventions to promote access to eyecare for non-dominant ethnic groups in high-income countries: a scoping review

PURPOSE

People who are distinct from the dominant ethnic group within a country can experience a variety of barriers to accessing eyecare services. We conducted a scoping review to map published interventions aimed at improving access to eyecare for non-Indigenous, non-dominant ethnic groups residing in high-income countries.

METHODS

We searched MEDLINE, Embase and Global Health for studies that described an intervention to promote access to eyecare for the target population. Two authors independently screened titles and abstracts followed by review of the full text of potentially relevant sources. For included studies, data extraction was carried out independently by two authors. Findings were summarised using a combination of descriptive statistics and thematic analysis.

RESULTS

We screened 5220 titles/abstracts, of which 82 reports describing 67 studies met the inclusion criteria. Most studies were conducted in the USA (90%), attempted to improve access for Black (48%) or Latinx (28%) communities at-risk for diabetic retinopathy (42%) and glaucoma (18%). Only 30% included the target population in the design of the intervention; those that did tended to be larger, collaborative initiatives, which addressed both patient and provider components of access. Forty-eight studies (72%) evaluated whether an intervention changed an outcome measure. Among these, attendance at a follow-up eye examination after screening was the most common (n=20/48, 42%), and directly supporting patients to overcome barriers to attendance was reported as the most effective approach. Building relationships between patients and providers, running coordinated, longitudinal initiatives and supporting reduction of root causes for inequity (education and economic) were key themes highlighted for success.

CONCLUSION

Although research evaluating interventions for non-dominant, non-Indigenous ethnic groups exist, key gaps remain. In particular, the paucity of relevant studies outside the USA needs to be addressed, and target communities need to be involved in the design and implementation of interventions more frequently.

Complex interventions to implement a diabetic retinopathy care pathway in the public health system in Kerala: the Nayanamritham study protocol

INTRODUCTION

Using a type 2 hybrid effectiveness-implementation design, we aim to pilot a diabetic retinopathy (DR) care pathway in the public health system in Kerala to understand how it can be scaled up to and sustained in the whole state.

METHODS AND ANALYSIS

Currently, there is no systematic DR screening programme in Kerala. Our intervention is a teleophthalmology pathway for people with diabetes in the non-communicable disease registers in 16 family health centres. The planned implementation strategy of the pathway will be developed based on the discrete Expert Recommendations for Implementing Change taxonomy. We will use both quantitative data from a cross-sectional study and qualitative data obtained from structured interviews, surveys and group discussions with stakeholders to report the effectiveness of the DR care pathway and evaluation of the implementation strategy.We will use logistic regression models to assess crude associations DR and sight-threatening diabetic retinopathy and fractional polynomials to account for the form of continuous covariates to predict uptake of DR screening. The primary effectiveness outcome is the proportion of patients in the non-communicable disease register with diabetes screened for DR over 12 months. Other outcomes include cost-effectiveness, safety, efficiency, patient satisfaction, timeliness and equity. The outcomes of evaluation of the implementation strategies include acceptability, feasibility, adoption, appropriateness, fidelity, penetration, costs and sustainability. Addition of more family health centres during the staggered initial phase of the programme will be considered as a sign of acceptability and feasibility. In the long term, the state-wide adoption of the DR care pathway will be considered as a successful outcome of the Nayanamritham study.

ETHICS AND DISSEMINATION

The study was approved by Indian Medical Research Council (2018-0551) dated 13 March 2019. Study findings will be disseminated through scientific publications and the report will inform adoption of the DR care pathway by Kerala state in future.

TRIAL REGISTRATION NUMBER

ISRCTN28942696.

Factors associated with the uptake of cataract surgery and interventions to improve uptake in low- and middle-income countries: A systematic review

Despite significant evidence around barriers hindering timely access to cataract surgery in low- and middle-income countries (LMICs), little is known about the strategies necessary to overcome them and the factors associated with improved access. Despite significant evidence that certain groups, women for example, experience disproportionate difficulties in access, little is known about how to improve the situation for them. Two reviews were conducted recently: Ramke et al., 2018 reported experimental and quasi-experimental evaluations of interventions to improve access of cataract surgical services, and Mercer et al., 2019 investigated interventions to improve gender equity. The aim of this systematic review was to collate, appraise and synthesise evidence from studies on factors associated with uptake of cataract surgery and strategies to improve the uptake in LMICs. We performed a literature search of five electronic databases, google scholar and a detailed reference review. The review identified several strategies that have been suggested to improve uptake of cataract surgery including surgical awareness campaigns; use of successfully operated persons as champions; removal of patient direct and indirect costs; regular community outreach; and ensuring high quality surgeries. Our findings provide the basis for the development of a targeted combination of interventions to improve access and ensure interventions which address barriers are included in planning cataract surgical services. Future research should seek to examine the effectiveness of these strategies and identify other relevant factors associated with intervention effects.

Retinopathy of prematurity: Addressing the emerging burden in developing countries

Retinopathy of prematurity has emerged and continues to be one of the leading causes of avoidable childhood blindness in low- and middle-income countries over the past few years. A major reason is the lack of adoption of effective and efficient screening for retinopathy of prematurity in various neonatal or newborn units across the countries. At the same time, there is an improvement in the survival rate of high-risk newborn babies which causes a further rise in retinopathy of prematurity. Most of the associated risk factors for retinopathy of prematurity are avoidable, therefore, various preventive strategies can be developed at various levels of healthcare facilities ranging from primary to tertiary level. The integration of appropriate retinopathy of prematurity intervention programs between healthcare departments and partnerships with other non-governmental eye care institutions would be an important as well as critical step to prevent blindness and visual impairment due to retinopathy of prematurity in India and other developing nations.

Horizontal inequity in the utilization of cataract surgery in Iran: Shahroud Eye Cohort Study, 2009-2014

Background: Since there was no evidence about economic inequity in utilization of cataract surgery in developing countries, such as Iran, this study was designed to measure horizontal inequity in the utilization of cataract surgery and its changes in an Iranian middleaged population in 2009 and 2014. Methods: Using data from the first and second phases of Shahroud Eye Cohort Study (2009-2014), the economic inequity in the utilization of cataract surgery in an Iranian middle-aged population aged 40-64 years in 2009 and 2014 was evaluated. The horizontal inequity index (HI) was determined using the indirect standardization method based on a nonlinear (probit) model and the concentration index (C) was decomposed into the contribution of each factor. The analyses were performed using STATA software version 12/SE, and significance level was set at less than 0.05. Results: The HI in the utilization of cataract surgery increased from 0.080 (95% CI: 0.011-0.098) in 2009 to 0.166 (95% CI: 0.0821- 0.228) in 2014. Decomposition of changes in the concentration index showed that among need and non-need variables, older age and economic status (being among the wealthiest 20%) were the greatest contributors, with shares of 67.5% and 57.5%%, respectively, which led to pro-rich inequity during the study periods. Conclusion: The present study demonstrated that utilization of cataract surgery did not have an equal distribution among economic quintiles, despite considering equal needs based on cataract severity. Results demonstrated that older age and economic status were the greatest contributors to HI increase in 2009 and 2014.

Reverse order method for teaching cataract surgery to residents

Objective

To implement a method to train residents in the performance of phacoemulsification surgery, with the steps completed in reverse chronological order and with the easiest step being undertaken first.

Methods and analysis

We created a method for training ophthalmology residents in which we taught phacoemulsification surgery in a series of steps learnt in reverse order. Each resident advanced through the teaching modules only after being approved in the final step and then progressed to the complete performance of surgeries. We analysed the rates of complications in the 2 years after introducing the new method.

Results

The new method allowed for a standardised approach that enabled replicated teaching of phacoemulsification regardless of instructor or student. After implementing the new method, residents performed 1817 phacoemulsification surgeries in the first year and 1860 in the second year, with posterior capsule rupture rates of 8.42% and 7.9%, respectively.

Conclusions

Teaching residents to perform the steps of phacoemulsification in a standardised reverse order resulted in low rates of complications.

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.

Developing and Optimising the Use of Logic Models in Systematic Reviews: Exploring Practice and Good Practice in the Use of Programme Theory in Reviews

BACKGROUND

Logic models are becoming an increasingly common feature of systematic reviews, as is the use of programme theory more generally in systematic reviewing. Logic models offer a framework to help reviewers to 'think' conceptually at various points during the review, and can be a useful tool in defining study inclusion and exclusion criteria, guiding the search strategy, identifying relevant outcomes, identifying mediating and moderating factors, and communicating review findings.

METHODS AND FINDINGS

In this paper we critique the use of logic models in systematic reviews and protocols drawn from two databases representing reviews of health interventions and international development interventions. Programme theory featured only in a minority of the reviews and protocols included. Despite drawing from different disciplinary traditions, reviews and protocols from both sources shared several limitations in their use of logic models and theories of change, and these were used almost unanimously to solely depict pictorially the way in which the intervention worked. Logic models and theories of change were consequently rarely used to communicate the findings of the review.

CONCLUSIONS

Logic models have the potential to be an aid integral throughout the systematic reviewing process. The absence of good practice around their use and development may be one reason for the apparent limited utility of logic models in many existing systematic reviews. These concerns are addressed in the second half of this paper, where we offer a set of principles in the use of logic models and an example of how we constructed a logic model for a review of school-based asthma interventions.