How have outreach eye health services been delivered globally? Protocol for a scoping review

Abstract

Introduction

In all countries, some population groups experience barriers to accessing eye health services, contributing to health inequities. Outreach is a common strategy used to deliver healthcare services to populations experiencing inequities. This scoping review aims to summarise the nature and extent of the existing literature describing outreach as a service delivery model to improve access to eye health services, particularly among populations experiencing inequities.

Methods and analysis

An information specialist will search academic databases (Medline, Embase and Global Health) without language restrictions to find peer-reviewed articles describing outreach eye health services, published in any country between 1 January 2010 and the search date. Grey literature sources will also be searched. In Covidence, two reviewers will independently screen titles and abstracts and subsequently relevant full texts against the inclusion criteria. Data extraction will also be performed independently by two reviewers in Covidence. This scoping review will summarise the characteristics of the included outreach eye health services, including the type of eye health service delivered, personnel involved, mode of transport, source of funding and whether the service targeted any specific PROGRESS-Plus group (Place of residence, Race/ethnicity/culture/language, Occupation, Gender/sex, Religion, Education, Socioeconomic status, Social capital, Plus). We will present our findings quantitatively using diagrams, tables and graphs.

Ethics and dissemination

Ethics approval was not sought, as this scoping review will use only publicly available reports. The results of this review will be disseminated through publication in a peer-reviewed journal and will be presented at eye health conferences. It will offer valuable insights for eye health providers, health and social service providers and policymakers who are interested in improving access to eye health services for populations experiencing inequities. This scoping review will inform a project in New Zealand which aims to develop outreach eye health services to populations experiencing inequities, such as unhoused people and refugees.

Registration

This protocol was registered on the Open Science Framework on 11 November 2025 (https://osf.io/vyz32).

STRENGTHS AND LIMITATIONS OF THIS STUDY.

• A comprehensive search, including grey literature, will be conducted with support from an experienced information specialist to identify the range of outreach models used globally.

• Title and abstract screening, study selection and data extraction will be performed independently by two reviewers with a third reviewer consulted when necessary.

• A potential limitation is that studies of outreach services may not provide comprehensive information on the service delivery model implemented.

Introduction

Rationale

Vision plays a crucial role in every aspect of our lives, including education, employment, social inclusion, independence and overall well-being. Globally, more than 1 billion people experience vision impairment, mostly due to uncorrected refractive error (including presbyopia) or cataract.^{1 2} Some population groups are disproportionately affected by vision loss, including Indigenous peoples,³ people experiencing financial hardship,⁴ people living in remote locations,⁴ those who are unhoused⁵ or incarcerated⁶ and disabled people.⁷ These eye health inequities occur because these population groups (referred hereafter as ‘populations experiencing inequities’⁸) face barriers to accessing eye health services, particularly those that are delivered in fixed, ‘conventional’ clinical settings such as private optometry practices and eye hospitals.^{1 9}

One strategy to improve access for population groups experiencing inequities is outreach services, where clinicians travel from their primary practice locations (eg, a private optometry practice) to provide temporary health services within community or institutional settings.10,12 For example, in eastern Taiwan, a ‘Mobile Vision Van Unit’ travels to hospitals and community centres in remote regions to provide comprehensive eye examinations,¹³ and in Nepal, there is a long history of outreach screening services to identify people needing cataract surgery.¹⁴ Expanding the network of outreach services can help to address health inequities by reaching individuals who face barriers to accessing healthcare services such as geographical isolation, financial hardship, language barriers or social stigma.¹⁵ Additionally, outreach services foster collaboration between health professionals and deliver services in familiar environments that enhance patient comfort and trust.¹⁶ Outreach services can integrate into communities and use locally available resources to provide cost-effective and impactful healthcare that caters to the needs of the population groups served.¹⁷

The inaugural World Report on Vision and the Lancet Commission on Global Eye Health both included calls for enhanced efforts to achieve Universal Health Coverage for eye health.^{1 2} Outreach services are an integral part of these efforts which could be scaled up in many parts of the world. We are currently developing models of outreach eye health services in Aotearoa New Zealand for populations experiencing inequities, and this scoping review will identify local and global models that can inform our approach. The existing evidence synthesised in this review can inform service providers and policymakers who are looking to strengthen and expand outreach eye health services.

Objective

The objective of this scoping review is to summarise how outreach eye health services have been delivered globally and whether they targeted any populations experiencing inequities. To achieve our objective, we will explore the following questions:

1. What are the key features and delivery models of the outreach eye health services?

2. Which populations experiencing inequities are targeted with outreach eye health services?

Methods and analysis

Protocol and registration

This scoping review protocol has been reported in accordance with the relevant components of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Extension for Scoping Reviews guidelines (online supplemental annex 1).¹⁸ We have also employed the methods described in the Joanna Briggs Institute Manual for Evidence Synthesis.^{19 20} This protocol was registered on the Open Science Framework on 11 November 2025 (https://osf.io/vyz32). This review is planned to take place from June 2026 to December 2026. Any post-registration protocol amendments will be reported in the final manuscript.

Eligibility criteria

We will include peer-reviewed and grey literature published after 1 January 2010 which describes an outreach eye health service for adults that has been implemented. For a service to be included in this review as outreach, the study must describe at least one characteristic of the outreach service (as listed in the data items below). We will exclude systematic reviews; however, their reference lists will be reviewed to identify additional relevant studies. We will exclude studies where the full text is not available, as well as conference abstracts and editorials. There will be no restrictions on publication language. We will translate any studies not published in English using Google Translate (available at https://translate.google.com) and aim to verify with native speakers (if any of the translation was unclear or ambiguous).

Population

Only outreach eye health services that provide care to adults aged 18 years of age and over will be included. If a service provides care to both adults and children, it will be included. We will exclude services which only target children under 18 years of age (eg, school vision screening).

Concept

We will include outreach eye health services where a clinician travels away from their regular practice location to provide temporary health services in a community-based or institutional setting.^{10 11} This includes mobile clinics (eg, a bus or a van) and fly-in fly-out services.²¹ We will adopt an inclusive approach in borderline cases where the classification of a service as outreach might be ambiguous.

We will include studies reporting any type of eye health service, including screening services (eg, for diabetic retinopathy or glaucoma), comprehensive examinations or surgery (eg, cataract surgery camps). Studies which incorporate other health services in addition to eye health (eg, diabetes checks and foot assessments) will also be included.

Services delivered exclusively via telehealth (defined as care provided remotely using technology such as video calls²²) will be excluded from this review, because the clinician is not physically travelling away from their primary practice location. Outreach services that involve a clinician travelling and interacting in person with the patient, alongside some elements of telehealth, will be included.

We will exclude studies whose primary objective was to conduct a cross-sectional survey using sampling methods to select individuals from a defined population, as the focus of this review is on services that people voluntarily attend.²³ Studies that only provide health education (eg, glaucoma awareness campaigns) without delivering any health service will be excluded.

Context

We will include outreach eye health services implemented in all countries, delivered in any level of the health system and in any health sector (public, private, not-for-profit).

Search strategy

An experienced information specialist (IG) designed the search strategy and conducted searches on the Medline, Embase and Global Health databases on 16 October 2025 using search terms related to outreach services and eye health (the full search strategy is provided in online supplemental annex 2).

The studies will be exported into Covidence systematic review software for screening (Veritas Health Innovation, Melbourne, Australia. Available at www.covidence.org). The reference lists of all included studies will be reviewed to identify additional relevant studies. We will also review the reference lists of systematic reviews, despite their exclusion from our scoping review.

A grey literature search will also be conducted to identify additional relevant reports. We will use the following search terms: [“Outreach” or “Mobile”] AND [“Eye Care” or “Eye Clinic” or “Eye Screening” or “Vision Screening”]. We will search the following organisational websites: WHO, International Agency for the Prevention of Blindness, World Council of Optometry, International Council of Ophthalmology, The Fred Hollows Foundation, Sightsavers and Orbis International. The first 20 results from each search will be screened for inclusion. If new reports describing outreach eye health services continue to be identified, we will extend the grey literature screening in increments of 10 results, up to a maximum of 50 results, until conceptual saturation is reached. This approach balances the breadth of the search with methodological practicality.¹⁹

One reviewer (EL) will conduct the search and identify relevant grey literature, which will be verified by a second reviewer to ensure accuracy and consistency. All relevant literature will then be added into Covidence for screening.

Study selection

Covidence will be used for study selection. Two reviewers will independently screen all titles and abstracts identified in the literature search to identify potentially relevant studies. Any disagreements will be resolved through discussion with a third reviewer. Each full-text article of selected studies will then be independently assessed by two reviewers to determine its eligibility for inclusion. If a study is excluded, the reason for its exclusion will be documented. Any discrepancies will again be resolved by discussion with a third reviewer. The entire study selection process will be outlined in a Preferred Reporting Items for Systematic Reviews and Meta-Analyses flow diagram.

Data charting process

A custom data extraction form will be created in Covidence. The data extraction form will be piloted on three studies by two reviewers, and amendments will be made as required. Data extraction will be carried out independently on each included study by two reviewers. Discrepancies will be resolved through discussion, and a third reviewer will be involved if required. If any information in an included study is unclear, we will make two attempts to contact the study’s authors via email to seek clarification.

Data items

We will extract the following information from each included study.

Publication characteristics

• Title.

• Author(s).

• Year of publication.

• Location of study (city/country).

• The number of participants who accessed the outreach service.

• The year(s) when the outreach service took place.

• The aim(s) of the study.

Characteristics of the outreach eye health services

• Structure of the service

  • Health sector (public/private/non-governmental organisation/not reported) and level of the health system (primary/secondary/tertiary/not reported) of the (i) personnel undertaking the outreach service and (ii) facility where the outreach service takes place.

  • Location, that is, where the eye health service was delivered (eg, inside a mobile vehicle/at a dedicated health facility/temporary clinic set up in a community location).

  • How often the outreach location was visited (one-off/recurring/not reported).

• Mode of transport (eg, plane, boat, truck, bus/van, motorbike, car, other, not reported).

• Type of eye health service provided (eg, comprehensive eye examinations/ screening/ocular surgery/unclear/not specified).

  • Whether any specific eye conditions were targeted (eg, refractive error/cataract/glaucoma/diabetic retinopathy/other/none—‘general eye care’).

• Personnel deployed to the outreach location.

  • Cadre (eg, ophthalmologist/optometrist/technician/nurse/other).

  • Qualification (eg, registered/in training/not reported).

  • Remuneration (eg, paid/volunteer/other incentive/not reported).

• Mobility of the ophthalmic equipment (permanently at outreach location/brought with the clinician/mixed/unclear/not reported).

• Source of funding (eg, government/private (including philanthropy)/educational institutions/other/not reported).

• Cost to the patient (no out-of-pocket payment/fully out-of-pocket payment/co-payment/not reported).

Targeted population groups

• Whether the outreach service explicitly targeted one or more population groups (including across any PROGRESS-Plus axis: Place of residence, Race/ethnicity/culture/language, Occupation, Gender/sex, Religion, Education, Socioeconomic status, Social capital, Plus).^{24 25}

• Any excluded population groups.

Synthesis of results

We will use figures (eg, bar charts) to quantify the number of studies targeting each PROGRESS-Plus group, service type and eye condition. If a study targets multiple PROGRESS-Plus groups (eg, race and gender), each group will be counted separately in our figures. We will create a global map to visualise the geographic distribution of the outreach services, and the number of studies reporting each data item will be summarised. Graphs and figures will be constructed using Excel and RStudio. Written summaries will be included with all figures to explain how the findings relate to our research objectives.

Patient and public involvement

This scoping review does not involve patient and public involvement, as it only draws on published and publicly available literature.

Ethics and dissemination

Since our scoping review will only include publicly available literature, ethics approval will not be sought. With an increasing global focus on reducing health inequities, there is an increasing demand for accessible service delivery models (such as outreach health services) which cater to the needs of populations experiencing inequities. To the best of our knowledge, there has been no scoping review to date which examines the delivery of outreach eye health services, particularly in addressing the needs of populations experiencing inequities. The findings from this scoping review will be disseminated through publication in an open-access, peer-reviewed journal and presented at eye health conferences. We anticipate that the findings from this scoping review will provide valuable insight for the development and implementation of outreach eye health services across New Zealand and elsewhere. This information will be useful for eye care providers, health and social service providers and policymakers who are interested in supporting outreach eye health services (particularly to populations experiencing inequities). It will also inform eye health researchers of existing evidence gaps and highlight priority areas for further investigation.