A systematic literature search was conducted following the Centre for Reviews and Dissemination (CRD) guidance and reported following the PRISMA statement. The search targeted studies on the nature and effectiveness of eye health promotion interventions. Electronic databases were searched: PubMed, Web of Science, and Medline, CINAHL and Academic Search Complete hosted on EBSCOHost. Searches were conducted from the inception of the Vision 2020 Campaign (1999) to November 2024. The search strategy included a combination of Medical Subject Headings (MeSH) and free-text terms related to “eye health promotion,” “vision care,” “health interventions,” “public health campaigns,” and “visual impairment prevention.” Supplementary searches involved hand-searching in relevant journals, reviewing reference lists of identified studies. (refer to underlying data: S1 Table). ²²

Studies were included if they met the following criteria: (1) peer-reviewed primary research studies (randomized controlled trials, quasi-experimental studies, observational studies, and qualitative studies); (2) focused on eye health promotion interventions aligned with the Ottawa Charter for Health Promotion action areas; (3) reported on outcomes such as improved access to eye care, behaviour change, visual acuity, prevention of blindness, or policy changes. Studies were excluded if they (1) did not address eye health promotion, (2) were systematic reviews or meta-analyses, (3) were published only as abstracts with insufficient information, or (4) were non-English publications.

The selection process followed PRISMA 2020 guidelines. All records retrieved from the searches were imported into EndNote X9 for reference management, and duplicates were removed. Two reviewers (HCM and SJN) independently screened the titles and abstracts against the inclusion criteria. Full-text articles of potentially relevant studies were retrieved and assessed independently by the same reviewers. Discrepancies were resolved through discussion or consultation with a third reviewer.

Data extraction followed the Template for Intervention Description and Replication (TIDieR) checklist to ensure detailed reporting of interventions. A standardized data extraction tool was created as a link on forms and piloted on three studies to ensure accuracy and consistency. Thereafter, it was finalised for use in the study.

Extracted data included study characteristics (authors, year, setting, design), participant demographics, intervention details (type, duration, delivery method), and outcomes. Quantitative data were extracted using a double entry approach where two independent reviewers entered it onto a previously piloted tool.

The methodological quality of all included studies was assessed using the Mixed Methods Appraisal Tool (MMAT) 2018 due to the included studies using differing or multiple methodologies. Two reviewers (HCM and SJN) independently appraised the quality each empirical studies across five criteria. Any disagreements were resolved through discussion with a third researcher. The checklist’s first two questions, which are the same for all study designs, evaluate whether the research questions are clearly stated and whether the data gathered allows them to be addressed. Based on the relevant study design, reviewers answer five distinct questions for each type of study. The possible answers are “Yes,” “No,” and “can’t tell.” A study’s score on the quality assessment tool is not an indicator in determining whether or not a study is included in the review. (refer to underlying data: S2 Table). ²²

Collation of the findings from this systematic review was guided by an eye health promotion intervention, and whether the articles assessed the nature or effectiveness of that intervention. Results were summarized using descriptive numerical descriptions of the data. A summary of findings was tabled, highlighting key outcomes, study characteristics, and quality assessments. The Ottawa Charter Framework was used as a framework to categorize and interpret the findings. Due to high heterogeneity in intervention types, populations, and outcome measures, meta-analysis was not feasible; therefore, a descriptive synthesis was conducted.

The initial search resulted in 15 554 citations after removing 14 672 duplicates ( Figure 1). ²² During title and abstract screening, 15 132 citations that did not meet the inclusion criteria, and were excluded yielding 332 citations eligible for full-text screening. After close examination during full-text screening, 133 citations were excluded as they were reporting on interventions conducted by non-eye health professionals and 139 citations reported on interventions that were not related to health promotion. Ultimately, 80 citations met the inclusion/exclusion criteria and were included in the systematic review synthesis.

The summary of the included studies and their characteristics such as study title, study aim, sample size, type of intervention, tools of measurement and other pertinent information is shown in S3 Table- refer to underlying data. ²² Studies included in this systematic review consist of different research designs, reflecting a diverse approach to answering the research question. Concerning study designs, a total of 21 cross-sectional, ^{25– 45} 18 cohort, ^{46– 63} and nine randomised control trials ^{64– 72} were included for analysis. Nine studies employed quantitative telemedicine and vision screening, ^{73– 81} while four studies utilised a quantitative clinical study.

The application of interventional approaches was noted in six studies. ^{82– 87} Additionally, three studies were experimental. ^{88– 90} Included were also two quantitative feasibility studies ^{91, 92} and four descriptive studies. ^{93– 96} Furthermore, three studies were community-based research, ^{97– 99} and two were conducted as nationwide or national surveys. ^{100, 101} Two studies which utilised a qualitative approach ^{102, 103} and one as a pilot study approach ¹⁰⁴ were included. The sample sizes ranged from 21 to 289 for qualitative studies and 53 to 1.4 million for quantitative studies.

Among the 80 studies that were assessed for quality using the MMAT 2018, 59 were assessed as quantitative, 12 as quantitative randomized controlled trial, seven as quantitative non-randomized studies and two as qualitative. The quality appraisal of the included studies using the MMAT 2018 tool revealed several consistent strengths and a few common limitations across the evaluated studies. All studies had well-defined research questions and collected data that was appropriate for answering them. The samples were representative of their respective target populations, and the sampling techniques used were relevant for every study. Additionally, a strong approach to data collecting and construct validity was demonstrated by the measurements employed to evaluate results, which were consistently adequate and suitable for qualitative research as well as descriptive, controlled trials. This demonstrates strong methodological alignment with the research aims and supports the external validity of the studies.

One significant limitation emerged concerning the risk of non-response bias. In majority of studies, it was characterized as “can’t tell,” meaning that non-response rates were either not recorded or were not sufficiently addressed. This omission raises concerns about the potential influence of selection bias and its impact on the generalizability of findings. All the studies used statistical analyses that were generally appropriate, and each study utilized methods aligned with its research questions and data type. This supports the internal validity of the findings and the credibility of reported associations or distributions. Despite the studies demonstrated methodological soundness in sampling, measurement, and analysis, the common absence of detailed reporting on nonresponse bias represents an area for improvement in future research reporting.

Among the included studies, 10 eye health promotion interventions were categorized as: health education, health counselling, vision screening, eye screening and training, health prevention, health promotion, health policy, ophthalmic intervention, comprehensive eye examination and screening for diabetic retinopathy. The detailed findings from included studies can be found in Table 1. ²² The eye health promotion intervention components were frequently underpinned by the WHO vision and eye screening implementation handbook and evidence-based guidelines. ^{105– 108}

The health education interventions in this review were from nine studies and focused on improving spectacle compliance, parental awareness of paediatric eye conditions, and patient education. Two studies used schools, ^{64, 89} three used hospitals ^{30, 67, 90} and four used community-based approaches for health promotion intervention. ^{63, 87, 95, 102} The interventions were delivered by optometrists, opticians and the majority being ophthalmologists ^{30, 67, 90, 102} emphasizing the role of eye care professionals in promoting vision health. The sample sizes varied, with some studies involving large populations (e.g., 15,404 participants, ⁶⁴ while others had smaller groups (e.g., 21 participants), ¹⁰² and a combined population sample of 24 892. ^{30, 63, 64, 67, 87, 89, 90, 95, 102} Health-related issues addressed primarily focused on education related to spectacle use and compliance, parental awareness of paediatric eye conditions, and online patient education. All the studies were population-centred, preventative, empowering, supportive and community-engaging. Only one study utilised online education suggesting a need for innovation and technology in health education. ¹⁰² There were no differences in interventions from studies conducted in high-income countries (HICs), ^{30, 63, 67, 87, 95, 102} upper-middle-income countries (UMICs) ⁶⁴ and (LMICs). ⁸⁹

Notably, one study found that online patient education significantly improved knowledge of eye health, highlighting the impactful potential of digital learning tools. ¹⁰² However, one study identified a gap in parental knowledge regarding paediatric vision care, suggesting the need for more targeted awareness campaigns. ⁹⁵ The study that tested educational interventions promoting spectacle use found no significant difference in purchase rates, ⁶⁴ while another demonstrated a significant improvement in spectacle compliance following a structured educational intervention. ⁸⁹ A significant improvement in follow-up compliance after educational intervention was observed. ^{30, 63, 87, 89, 90} Overall, the effectiveness of these interventions varied, with most studies demonstrating clear improvements in eye health awareness and behavioural change, while a few showed limited impact, emphasizing the need for continuous evaluation and adaptation of health education strategies. All studies were limited in their interventions, with a lack of structured monitoring and evaluation, which is crucial for assessing the long-term impact of health education initiatives.

The health counselling intervention in one included study aimed to address protective eyewear use, patient education, and behavioural counselling in monocular patients. One study from a HIC investigated counselling practices related to protective eyewear for monocular patients. ³² A study with a sample of 60 participants highlighted gaps in health counselling practices, and the need for structured and consistent patient education strategies in primary care settings. Ophthalmologists were the eye healthcare professionals involved in this intervention. ³² The findings showed that 56.7% of patients did not recall receiving counselling, while 35% had received advice, and 8.3% remained unsure of any counselling provided. ³²

Despite the potential benefits of health counselling, lack of continuous monitoring and follow-up were flagged as key limitations of these interventions. The intervention in this study had behavioural change strategies, evidence-based approaches, and preventive counselling integrated however community and family participation, technological innovation, and emotional support were lacking. ³² Additionally, ethical and confidential practices were not addressed.

A total of 25 studies had vision screening interventions, mostly aimed at identifying various ocular conditions across diverse populations. The vision screenings were conducted in schools, ^{31, 35, 38, 41, 45, 46, 51, 53, 58, 62, 77, 81, 93} within communities, ^{25, 26, 55, 57, 66, 71, 72, 91, 94, 104} and hospital settings, ^{49, 80, 101} and were aimed at improving early detection and timely intervention. The interventions involved optometrists, ophthalmologists, orthoptists, and opticians, demonstrating a multidisciplinary approach to vision screening. Sample sizes ranged from 113 participants ⁹¹ in a study evaluating tele-ophthalmology for remote screening, to 1.4 million, ⁸⁴ in a study assessing national vision screening coverage.

These studies highlight the importance of large-scale screening efforts in detecting and managing vision problems early. The key health issues addressed by vision screening were possible refractive errors and ocular conditions in children. In conducting the vision screening, visual acuity was assessed in all studies, while refractive error screening was evaluated in 19 studies ^{26, 35, 38, 41, 46, 49, 51, 53, 55, 57, 58, 66, 71, 72, 77, 91, 93, 94, 104} and binocular alignment assessed in 11 studies. ^{26, 35, 38, 41, 45, 46, 55, 57, 58, 77, 94} Other studies also screened for colour vision, ^{38, 46, 58, 81} intraocular pressure, ^{25, 38, 49, 57, 66, 71, 91, 93, 104} intraocular health, ^{25, 35, 41, 46, 49, 55, 57, 66, 71, 77, 80, 91, 93, 94, 101, 104} contrast sensitivity ^{71, 93} and visual fields. ^{25, 71, 80, 81, 91} Most of the vision screening interventions were conducted in high-income countries (HICs), a few in UMICs ^{35, 41, 51, 93} and only two ^{31, 62} in LMICs.

One study assessed the spectacles cut-offs for providing spectacle in a school-based vision screening suggesting that children with ≥-0.75D myopia, >+1.00D hyperopia, and >+0.75D astigmatism had significantly greater improvements in vision than those with lower refractive errors. ⁵¹ However, during follow-up, there were only 31% of children wearing their spectacles. Similarly, an assessment of the Self-Assisted Vision Examination (SAVE) method found that 66% of the children were referred for refraction, and 81.3% of those who received glasses were wearing them at follow-up, indicating high compliance. ⁶² Another study reported that 53% of referred children from the vision screening had visual impairment eligible for spectacle correction. ⁴⁵ These findings suggest that while school-based screening improves detection, spectacle compliance remains a challenge. ^{45, 51, 62} Community-based screening programs were effective in increasing early detection of ocular diseases; however, challenges related to follow-ups and referrals were noted. Two USA-based studies identified inefficiencies in traditional vision screening programs, associated with over-referrals and poor follow-ups. ^{53, 104} Another found that 83% of individuals attended their optometric exams following a community screening, with 70.5% being referred to ophthalmology for further evaluation. ⁶⁶ These studies emphasized the importance of integrating structured referral pathways and follow-up mechanisms into community-based vision screening interventions. ^{53, 66, 104}

Remote vision screening using teleophthalmology has been identified as feasible and effective for detecting retinopathy and other eye diseases in rural areas. ^{49, 91} Approximately 74.7% of neonates underwent vision screening, emphasizing broad national-level coverage. ¹⁰¹ A study assessing preschool vision screening found that 65% of referred children attended follow-up eye exams, with 74% of those examined prescribed spectacles. ³⁸ Meanwhile, the Vision First Check Program increased preschool participation in vision care, reinforcing the need for integrated screening programs at early childhood levels. ^{38, 94, 101}

A study on mobile ophthalmic unit screenings reported that 88.5% of diagnoses from mobile screenings matched tertiary hospital evaluations, validating their accuracy and effectiveness. ⁵⁷ Nearly 100% of school screening coverage, with 9-15% of screened children requiring referrals, demonstrated high screening reach coupled with referral inefficiencies. ^{25, 57, 58} Screening for vision impairment among elderly populations revealed high prevalence rates but limited post-screening interventions. ^{25, 80} A 38% prevalence of visual impairment reported in nursing home residents underscores high unmet needs in elderly eye care. ⁷² The vision screening in frail older adults reported no significant improvement in visual acuity after 12 months, suggesting the need for comprehensive management beyond screening alone. ^{71, 72, 80}

Only one ⁸⁵ was included in the systematic review which aimed to assess the scaling up of screening training to improve the detection, management, and referral of common eye conditions. The intervention included all the training program criteria and was conducted in school settings by optometrists and ophthalmologists. This intervention involved 355 individuals who were teachers and school directors, trained in vision programs. The overall health issues addressed in this intervention aimed to equip healthcare providers, teachers, and community health workers with the necessary skills and knowledge to increase the uptake of eye health services, particularly in underserved regions in Peru. The effectiveness of the intervention was based on the successful training of 355 teachers and school directors, from 315 schools across 24 districts, and led to the expansion of vision screening services in two of the eight provinces. Training of non-eye-care professionals can significantly improve access to vision screenings in remote areas, thereby enhancing early detection and referral for comprehensive eye examinations.

The overall aim of the four included studies was to address lifestyle modification for diabetic retinopathy management, treatment for age-related macular degeneration, uptake for paediatric rheumatology screening, and compliance with spectacle wear. ^{34, 36, 82, 83} Three of the studies were conducted by ophthalmologists, ^{34, 82, 83} and one was conducted by ophthalmic assistants. ³⁶ The health prevention interventions were conducted in schools, ³⁶ primary care centres, ⁸² and hospitals, ^{34, 83} and were aimed at enhancing adherence to spectacles wear and promote early detection and management of ocular conditions. Three of the studies were conducted in HICs ^{34, 82, 83} and one in a LMIC. ³⁶ The cumulative sample size across the studies in health prevention was 2,000 participants. The intervention reviewed integrated multiple strategies to enhance compliance, foster behavioural change, and ensure uptake of vision care services. Four studies ensured population-centred and inclusive approaches, preventative and proactive, evidence-based approaches, empowerment and capacity-building, behavioural change and skills development, supportive environments, and community engagement. ^{34, 36, 82, 83} Two studies involved multi-sectoral collaboration ^{36, 83} ; one study included innovation and technology, ⁸³ whereas none of the studies explicitly included a structured monitoring and evaluation plan.

The effectiveness of the health prevention intervention was analysed based on compliance, patient behaviour change, and adherence to eye care practices. Studies assessing the impact of lifestyle interventions on the development of diabetic retinopathy in participants with impaired glucose tolerance found that microaneurysms were significantly lower in the intervention group (24%) as compared to the control group (38%) (p = 0.029), indicating that lifestyle changes had long-term metabolic benefits. ⁸² Micronutrient supplement usage as a preventative measure for advanced age-related macular degeneration was found to be 93% among participants, with 61% using the correct dosage as per Age-Related Eye Disease Studies recommendations. ³⁴ The effectiveness of quality improvement interventions in improving compliance with eye screening guidelines among paediatric rheumatology patients receiving hydroxychloroquine (HCQ) was 65% of baseline compliance, which increased to 85% after the implementation of quality improvement interventions and sustained over 10 months. ⁸³ Investigated spectacle compliance among students, provided with spectacles during a school screening programme, showed low compliance, with only 29.8% wearing their spectacles. ³⁶ Additionally, 35% of students had lost their spectacles during the follow-up session. ³⁶

The overall aim of the six included studies was to assess health promotion interventions aimed at improving eye health literacy, change behaviours related to vision care, prevention of myopia, and increasing access to eye services in different populations. ^{44, 54, 84, 86, 88, 103} Four of the studies were conducted by ophthalmologists, ^{54, 84, 86, 88} one by optometrists, ¹⁰³ and the last one was conducted by a collaboration of ophthalmologists and optometrists. ⁴⁴ The health promotion interventions were conducted in schools ^{44, 86, 88} and community-based settings ^{54, 84, 103} to address eye health literacy, prevention and awareness of eye conditions, and behavioural change towards eye health knowledge and attitudes. Three of the studies were conducted in HICs, ^{54, 86, 103} one in an UMI ⁸⁸ and two in a LMICs. ^{44, 84} The cumulative sample size across the studies in health promotion was 3 741 participants. Six studies ensured population-centred and inclusive approaches, preventative and proactive, evidence-based approaches, empowerment and capacity-building, supportive environments, innovation and technology, and community engagement. ^{44, 54, 84, 86, 88, 103} Three studies involved multi-sectoral collaboration ^{54, 84, 103} ; five studies involved behavioural change and skills development, ^{54, 84, 86, 88, 103} and two had a monitoring and evaluation plan. ^{84, 88}

Awareness, behavioural change, disease prevention, and eye care service accessibility were at the centre of the health promotion intervention analysis in this studies. The effectiveness of a school-based eye health promotion intervention on health literacy, attitudes, and behaviours among children revealed a 10-20% increase in good knowledge, with significant improvements in awareness of common eye diseases (p < 0.001). ⁴⁴ Similarly, another study reported that 100% of primary school learners in the intervention group consistently wore their spectacles post-intervention contrasting the 53.3% in the control group (p<0.05). This further highlighting a significant impact on eye health behaviours and awareness. ⁸⁸ The impact of community-based improvements in water and sanitation facilities on reducing active trachoma prevalence showed a decrease from 13.3% to 1.4% over two years after the implementation of the SAFE strategy (Surgery, Antibiotics, Facial Cleanliness, and Environmental Improvements). ⁸⁴ Two studies investigated the relationship between outdoor activity and myopia control. ^{54, 86} One study found that for each additional hour of outdoor activity per day, the risk of developing myopia was reduced by 10% (OR = 0.90, 95% CI: 0.84–0.96, p = 0.004). ⁵⁴ Meanwhile, another study reported that children who participated in outdoor recess had significantly lower myopia onset rates (8.41%) compared to the control group (17.65%, p < 0.001). ⁸⁶ In exploring the barriers affecting access to eye care services in at-risk populations, a study found many participants considered eye health with vision loss and spectacle needs, neglecting the preventative aspects of eye care. ¹⁰³

The health policy intervention evaluated access to and adequacy of eye care services, and only one study addressed the health policy. ³³ The study under review included 500 participants represented through a community-based approach. The intervention addressed limited access to eye care services and was conducted in an UMIC. Optometrists and ophthalmologists were at the centre of the service delivery. ³³ The study took a population-centred approach and emphasized preventive, proactive, and evidence-based strategies while considering multi-sectoral collaboration, empowerment, and community engagement as integral components of effective policy interventions. ³³ The intervention lacked innovative technology and monitoring and evaluation. Severely inadequate access to eye care services was identified, with only 38.6% of Jamaicans receiving an eye exam within the recommended three-year interval, while 43.4% had never had an eye exam. The eye care provider-to-population ratio was only 2.04 per 100,000, significantly lower than population requires, highlighting critical workforce shortages. ³³

Ophthalmic intervention programs involved 11 studies. ^{27, 40, 48, 50, 56, 60, 65, 68, 73, 92, 96} The studies aimed to address key health issues such as access to routine eye care, quality of life for visually impaired individuals, disease-specific interventions, and the role of technology and mobile-based programs in improving eye care utilization. Four of the studies were conducted by ophthalmologists, ^{27, 40, 50, 60} five by both ophthalmologists and optometrists, ^{48, 56, 65, 73, 96} one by opticians, ⁹² and another one by ophthalmologists and ophthalmic technicians. ⁶⁸ The ophthalmic intervention programs were conducted in retirement homes, ^{56, 65, 96} hospitals, ^{48, 50, 60, 73} community centres, ^{27, 68} primary care centres, ⁹² and workplace settings, ⁴⁰ and sought to address the major ophthalmic health issues. Nine of the studies were conducted in HICs, ^{27, 40, 48, 50, 56, 65, 73, 92, 96} one in a MIC, ⁶⁸ and one in a LMIC. ⁶⁰ The overall sample size across the 11 studies was 10,593, with individual study sample sizes ranging from 53 to 2,530 participants. All the studies ensured population-centred and inclusive approaches, preventative and proactive, evidence-based approaches, and supportive environments. Ten studies included innovation and technology, ^{27, 40, 48, 50, 60, 65, 68, 73, 92, 96} and nine studies included both empowerment and community engagement. ^{27, 40, 48, 50, 56, 60, 65, 68, 96} Four studies involved multi-sectoral collaboration, ^{40, 48, 73, 96} two involved behavioural change ^{27, 40} and development, and one had a monitoring and evaluation plan. ⁵⁰

In a Canadian optometrists-led program, participants in long-term care facilities and retirement homes had at least one eye condition with about 28.6% of the participants in need of specialised eye care. ⁹⁶ A culturally specific diabetic eye screening program for African Americans detected 10% of patients in need of urgent ophthalmologic care. ²⁷ Furthermore, 22% needed follow-up in 3 months, and 67% required regular eye care. ²⁷ A positive predictive value of 18% has been found in a tele ophthalmology-based glaucoma screening, highlighting a high agreement between the quality of ophthalmic intervention programs conducted by optometrists and hospital technicians. ⁷³ A glaucoma screening and early detection study showed 88% participation, leading to 2% glaucoma diagnosis and 3% with ocular hypertension. ⁹²

A nursing home-based low-vision rehabilitation program identified 198 individuals with low vision, of whom 91 (68.9%) participated in interventions and cognitive and physical limitations were identified as barriers to the effectiveness of the rehabilitation. ⁶⁵ Evaluated national telemedicine-based retinopathy of prematurity (ROP) screening program successfully screened 2,188 infants across 20 neonatal intensive care units (NICUs) with plans to expand to 31 NICUs. ⁴⁸ Among them, 26% (n=566) were diagnosed with ROP. One study identified a 21% prevalence of ROP among preterm infants, reinforcing the need for enhanced neonatal eye screening in low-resource settings. ⁶⁰ Another study demonstrated that the progression of ROP can be reduced by a targeted oxygen therapy protocol with only 23% of cases advancing beyond Stage 2 compared to the 44% found prior to protocol implementation. ⁵⁰

The prevalence of dry eye diseases among visual display terminal workers revealed that 60% of participants are diagnosed with the diseases, and the study identified prolonged screen exposure as a risk factor. ⁴⁰ Vision-enhancing interventions such as cataract surgery, and refractive error correction have been found to have no significant improvement in physical function and cognitive status among nursing home residents. ⁵⁶ In one study, community-based and mobile health interventions reported higher effectiveness in eye care utilization over conventional screening methods. ⁶⁸ Furthermore, patients referred via mHealth were 1.7 times more likely to utilize eye care services as opposed to conventional screening referrals (OR: 1.7, 95% CI: 1.2–2.4). ⁶⁸

Comprehensive vision examinations were conducted in six studies. ^{37, 59, 69, 70, 98, 100} The studies aimed to address key health issues such as refractive errors in adult and child myopia prevention, and compliance with spectacles wear. Four of the studies were conducted by optometrists, ^{59, 70, 98, 100} one by refractionists ⁶⁹ and one by both ophthalmologists and optometrists. ³⁷ These comprehensive vision examinations were conducted in schools, ^{37, 59, 69, 100} retirement homes ⁷⁰ and community-based settings. ⁹⁸ Three of the studies were conducted in HICs ^{70, 98, 100} and the other three in UMICs. ^{37, 59, 69} The included studies had a cumulative sample size of 10,496 participants. All the studies included visual acuity in their examination. ^{37, 59, 69, 70, 98, 100} Five studies included refraction, ^{37, 59, 69, 98, 100} two studies ^{37, 100} binocular and eye coordination testing and only one study included patient history. ¹⁰⁰ Eye health was included in two studies ^{37, 100} similar to follow-up and referral. ^{59, 69} Only one study included both colour vision and patient education in their examinations. ¹⁰⁰ Notably, no studies included intraocular pressure evaluation, pupil examination and dry eye assessment as part of the vision examination.

Comprehensive vision screening programs in school settings were effective in identifying refractive errors, amblyopia, and other eye conditions. One study conducted a mandatory eye examination study among children entering the public school system, revealing that 740 children had spectacles prescribed, 181 were diagnosed with amblyopia, and 123 were diagnosed with strabismus. ¹⁰⁰ Similarly, in two studies investigating the outcomes of free spectacle provision, one study showed a low compliance rate of 13.4%, despite the provision of free spectacles ⁵⁹ and a randomised control study show no evidence that receiving free eyeglasses worsened uncorrected visual acuity among middle school students. ⁶⁹

Studies evaluating outdoor activity as a preventative measure for myopia consistently found a significant effect. Analysing the association between outdoor time and myopia onset in children aged 3-9 years found that greater time spent outdoors during these ages reduced the risk of developing myopia in later childhood. ⁹⁸ The most protective effect was observed at age nine, with a hazard ratio (HR) of 0.86 (95% CI: 0.78–0.93, p = 0.001) per standard deviation increase in outdoor time per day. ⁹⁸ One study which examined the impact of outdoor activity and other factors on myopia progression among primary school students found that longer axial length and myopia progression were a result of less outdoor activity, more indoor studying, maternal myopia, and urban residence. ³⁷

Fourteen studies were included in the screening for diabetic retinopathy intervention. Overall the studies sought to establish the efficacy of diabetic retinopathy screening interventions in improving early detection, improving patient uptake, and integrating screening within broader diabetes management systems. ^{28, 29, 39, 42, 43, 47, 52, 61, 74– 76, 78, 97, 99} Eleven studies involved ophthalmologists, ^{28, 29, 42, 47, 52, 74– 76, 78, 97, 99} four involved optometrists ^{43, 61, 76, 97} and three involved orthoptists. ^{29, 52, 78} Additionally, two studies involved ophthalmic assistants ^{39, 99} and one involved ophthalmic nurses. ⁷⁵ Five studies were conducted in primary care centres, ^{29, 47, 61, 78, 99} five in community-based settings ^{28, 39, 43, 52, 76} and four in hospitals. ^{42, 74, 75, 97} Ten of the studies were conducted in HICs, ^{28, 29, 42, 47, 52, 61, 74, 75, 78, 97} three in LMICs ^{39, 43, 99} and one was from UMIC. ⁷⁶ Across the 14 selected studies reviewed, individual study sample sizes ranged from 95 to 782,799 participants, demonstrating a wide range of implementation scales. All the studies targeted diabetic patients to ensure early detection for the prevention of progressive diabetic retinopathy. All the studies reported using non-invasive screening methods and only 13 studies detected early signs of diabetic retinopathy. ^{28, 29, 39, 42, 47, 52, 61, 74– 76, 78, 97, 99} Risk assessment for progression was included in 12 studies ^{28, 29, 39, 43, 47, 52, 61, 75, 76, 78, 97, 99} ; nine adhered to screening guidelines, ^{28, 29, 42, 74– 76, 78, 97, 99} and five included patient education and counselling in their screening. ^{29, 52, 75, 78, 99} Seven studies followed a structured follow-up system ^{29, 43, 47, 52, 75, 97, 99} and ten considered cost-effective and accessible screening, ^{39, 42, 43, 47, 52, 61, 75, 78, 97, 99} with 13 integrating the screening for diabetic retinopathy with broader diabetes care. ^{28, 39, 42, 43, 47, 52, 61, 74– 76, 78, 97, 99}

Studies showed that intervention from early detection significantly enhanced diabetic retinopathy (DR) identification rates with 39% of screened diabetic patients having DR, 9.8% having sight-threatening DR, and 5.5% having visual impairment. ⁷⁶ Similarly, another study reported that 33.1% of screened patients had suspected DR, while 65.3% showed no signs of disease. ⁴² Two studies reporting on telemedicine demonstrated web-based screening in primary care effective at 89.6% of retinal images gradable and 22.7% prevalence of DR detected through teleophthalmology screening. ^{47, 76} Another study found that digital fundus photography had 90% sensitivity in detecting severe DR. ⁷⁴

Two studies reporting on mobile screening programs for DR reported effectiveness particularly in rural and underserved areas where 70.25% of patients reported not having seen an ophthalmologist in over two years whilst 33% had received eye care annually. ^{29, 52} Of the studies that focused on community-based programs, significant progress was observed in detecting DR however, only 32% of eligible participants in one study participating in the screening for DR due to lack of awareness. ^{39, 43} In one study, the effectiveness of nurse-led DR screening clinics achieved a 92% success rate with ophthalmologists. ⁷⁵

This review has identified a number of gaps that may be considered in future studies. This review was conducted in English which may result in language bias potentially excluding relevant research published in other languages. Many interventions, especially vision screening programs lacked long-term follow-up making it difficult to assess sustained outcomes. Most studies were conducted in high-income countries, with limited research from low-and middle-income settings affecting the generalizability of findings. The integration of monitoring and evaluation into the design of intervention will strengthen evidence and increase understanding of future programme effectiveness. However, this review provides an important contribution as the first to explore the nature and effectiveness of eye health promotion interventions globally. It employed a rigorous methodological approach to critique the quality of the included studies and systematically evaluated the interventions through the lens of the Ottawa Charter for Health Promotion.