Challenges and barriers to early detection of primary open-angle glaucoma at the primary health care level: A scoping review

Search strategy for the identification of studies addressing the review question

Primary studies addressing the main review questions were found by a subject specialist. The first author collaborated to create a thorough search strategy, scoping and repeatable searches of reliable bibliographic databases, indexing services, and platforms, followed by other supplementary information sources. Before it was tested on a selection of records from the PubMed database, the draft search strategy was reviewed by all the authors to ensure that the indexing terminology and Medical Subject Headings (MeSH) descriptors were used correctly.

These studies were screened to determine whether they qualified for inclusion in this review or not. PN carried out all of the primary electronic searches, and TSS did the supplementary systematic searches with the help of expert librarians from the University of KwaZulu-Natal, utilising a predetermined search strategy as indicated in Table 2 below.

Electronic searches

The first author conducted a manual search by looking through the “Related articles” to find more studies. A variety of databases, including PubMed, Web of Science, Science Direct, Scopus, and EBSCOhost, were systematically searched for peer-reviewed articles published in English from the date of inception and May 2024. Under the EBSCOhost platform, the following databases were explored: Academic Search Complete, Health Source: Consumer Edition, Health Source: Nursing/Academic Edition, and Open Dissertation. To find relevant articles, the searches employed both free-text and controlled vocabulary phrases (like MeSH). Systematic reviews and other forms of published literature review papers, whether or not they were peer-reviewed, were not included; only primary research studies were. To locate more primary studies, however, the reference lists of relevant reviews, preprints, conference abstract papers, and full-text articles were combed. All of the citations discovered once the search was finished were added to EndNote version 21. The second author conducted an independent search to ensure no resources were overlooked during the process.

Two independent reviewers conducted a multi-step study selection process in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analysis extension for scoping reviews (PRISMA-ScR) to minimise bias and errors. The study selection process consisted of three screening stages:

After completing the full-text screening, the two reviewers conducted a secondary search of the reference lists of all included studies to identify any relevant articles that may have been overlooked during the initial database search. All studies that reported the prevalence, screening, and diagnosis of POAG at any level of health care were included for data extraction, while studies focusing on other types of glaucoma were excluded.

After conducting a full-text screening of the articles, two independent reviewers, PN and ZM, extracted data from all the included resources using a data extraction tool designed with Google Forms (Supplementary document S3).²⁵ This data extraction tool can be found in Supplementary Document S3, in the Zenodo repository at this link: https://doi.org/10.5281/zenodo.17097386 Mapping evidence on the screening/diagnosis of primary open angle glaucoma.

The authors extracted data, which was subsequently verified by the third author. All discrepancies were resolved through discussion, with the third author available for additional input where necessary. The two reviewers worked independently to collate data, including the study aim, sample size, was the screening or diagnosis was done, where the screening was conducted, theoretical approach, and the methods used for data collection and analysis. This process was carried out in duplicate to minimise data entry errors and bias.

The data from the scoping review were further analysed for the purpose of identifying emerging themes. By reading the included articles over a few times, themes were identified and categorised, adapting the approach outlined by Braun & Clarke for analysis.²⁶ Steps undertaken to identify themes and sub-themes included: Familiarization, Generating initial codes, Searching for themes, Reviewing themes, Defining and Naming themes, and finally Writing up. Familiarization refers to reading the included articles repeatedly to ensure a deep understanding of the data in its entirety and context. Generating Initial Codes pertains to systematically identifying data by reading to describe features of interest. Searching for themes is where one assembles information from all the articles to identify relevance into potential themes. Reviewing themes involves refining themes to ensure the accuracy of the information. Defining and Naming Themes refers to distinctly defining what each theme is about and giving it a relevant name. Writing up, which is the final step and refers to combining the analysis into a logical narrative linking back to the research question.

Ethical consideration

Although ethical clearance may not have been strictly necessary for this scoping review since it utilizes publicly available resources, it was still a requirement to obtain ethical approval. This review is part of a larger research project that investigates the barriers and challenges related to the prevalence of glaucoma, particularly in detecting Primary Open Angle Glaucoma at the primary healthcare level. The ethical clearance was obtained from the Biomedical Research Ethical Committee at the University of KwaZulu-Natal (BREC/00007182/2024).

Characteristics of the included studies

A total of 21 resources were included in this review study, as outlined in Table 3 below. Among these, nine studies involved participants from Africa; one from Morocco, and eight specifically from Sub-Saharan Africa. While most studies were assumed to be screening studies, a review of the methodologies revealed that only seven actually met the criteria for screening, as the remaining studies focused on diagnosis (n=14). Additionally, the majority of the studies were conducted at the secondary healthcare level (n=12), while a minority were conducted at the tertiary healthcare level (n=3). In most cases, ophthalmologists were responsible for performing the screenings or diagnoses (n=12). In two studies, optometrists were involved, while the remaining studies (n=7) had screenings or diagnoses conducted by nurses, technicians, general practitioners, or other medical personnel. The equipment used for screening and diagnosis varied among the studies, however, visual acuity, intraocular pressure, and visual field assessments were conducted in all studies.

Limited resources

Various studies have documented significant resources constraints affecting screening and diagnosing of POAG within their respective health settings.^3,13,31,32 Scarce resources encompassed insufficiently trained staff, inadequate equipment, and deficient funding mechanisms.^3,16,33 In comparable contexts, characterised by equipment shortages and underfunded healthcare infrastructure, countries such as Nigeria, Ghana, Tanzania and Kenya implemented social health insurance schemes that facilitated resource allocation to healthcare facilities enhancing patient accessibility to essential services.³⁴ Ensuring robust institutional frameworks and governance structures to ensure availability of basic resources in POAG management would enhance screening efficacy and mitigate visual impairment resulting from ocular disease-related complications.³⁴

Characteristically, patients in some studies presented with chief complaints indicative of pre-existing POAG manifestation.^13,31,32,35 However, two additional studies used structured questionnaires comprising appropriately selected items as foundational screening instruments for POAG.^3,27 These screening tools incorporated clearly delineated family and medical history inquiries, which were administered during the patient evaluation process.^32,33 Consistent with existing evidence demonstrating an association between POAG and individuals with a positive family history of glaucoma or specific glaucoma-related comorbidities, the present findings corroborate the established data. Such patients warrant enhanced surveillance, given their elevated risk for disease development.^6,34

Notwithstanding the markedly elevated prevalence of glaucoma-related blindness in low-income countries, particularly throughout Sub-Saharan Africa (SSA),^13,17 this review identified only a single study specifically addressing glaucoma screening practices within the SSA region.³⁵ Conversely, seven studies reported on the diagnostic evaluation of the condition.^{12,16,29,35–38}

Globally, the ratio of patients to ophthalmologists is concerningly low.^{12,27,36–39} As ophthalmologists are highly trained medical surgeons, It is concerning that most screenings and diagnoses, in these studies, were performed by this specialist cadre.¹² This situation is exacerbated by the fact that these eye specialists are often located at secondary or tertiary healthcare levels, where they deal with managed of advanced disease. The lack of screening at a primary health level compromises their time and skill, deviating their attention from serious disease management and undermining the early detection of glaucoma.³⁷ It has been reported that most patients diagnosed at these levels had already lost some degree of peripheral vision.³⁷ To improve early detection, it is crucial to conduct screenings at the primary healthcare level, with basic management and treatment being administered by optometrists as primary eye health practitioners. This approach would reduce the workload on ophthalmologists, allowing them to focus more on surgical procedures. This review further indicated that few optometrists are involved in the screening of POAG, as only two studies reported optometrists performing screenings.^33,38 Apart from being primary gatekeepers of eye care, optometrists are more accessible and better distributed to patients for early detection and diagnosis compared to eye specialists.³⁸ Overall, the scarcity and distribution of human resources in eye care was identified as a significant barrier to the early detection of POAG.^16,27,33

Access to care

Accessibility challenges, particularly related to transportation and reaching rural areas, also pose significant obstacles.^28,31,40 Infrastural deficiencies, Inadequate equipment and poor healthcare facility conditions play a huge role in inhibiting healthcare at primary healthcare level.⁴⁰ Socio-cultural factors such as limited health literacy, preferences for traditional medicine and gender-based barriers contribute to the underutilization of primary healthcare (PHC) services. Furthermore geographical obstacles, inadequate referral system and ineffective policy implementation impede the effectiveness of PHC. Overcoming these challenges necessitates a comprehensive, multi-faceted strategy.⁴⁰ Abolaji Kehinde and Okunlola argued that expanding health insurance schemes and providing government subsidies for vulnerable populations can enhance financial access which can be part of the solution for healthcare lack of accessibility.⁴⁰

Disease awareness

A lack of public awareness regarding the seriousness of POAG and the importance of early detection has been identified as a barrier.^6,13,39,41 The world Health Organization (WHO) package of Essential noncommunicable Disease Interventions (WHO PEN) was developed to support the prevention, early and treatment of noncommunicable diseases.⁴² These interventions are cost effective and action oriented strategies, already implemented in high income countries which has had a huge impact in lowering disease and increasing level of health care,unfortunately this is yet to be executed in in low income countries hence the high prevalence of diseases.⁴² Also community engagement, health education and effective policy enforcement are essential for addressing socio-cultural and governance related challenges that contribute to lack of disease awareness by population in low income countries. Additionally in agreement with the study, Tesema A suggested improving accessibility through mobile health services, telemedicine and intergration of primary healthcare with secondary healthcare can strengthen service delivery and disease awareness.⁴²

Screening guidelines

The absence of a standardized global screening protocol, defining required equipment and guidelines for glaucoma screening, was noted as a limitation in this study.^32,39,41 The use of different equipment by different health professionals in each study reveals inconsistencies and a lack of uniformity in diagnosing primary open-angle glaucoma. There is no standardised framework dictating how screenings and diagnoses should be conducted, leading to a high prevalence of cases. Additionally, many studies demonstrated varying limitations in diagnostic techniques and equipment related to glaucoma screening at the primary healthcare level.³⁷

Moreover, the increasing demand for eye care personnel has contributed to delays in the early detection of POAG, with many patients having to wait over six months to see a specialist.^27,28 Follow-up care has also been identified as a challenge; due to long waiting times, patients often do not return to the hospital until they have lost their vision significantly, resulting in poor prognosis and ineffective treatment outcomes.⁴³

The current scoping review highlights the lack of screening for primary open-angle glaucoma at the primary healthcare levelThe research underscores the critical importance of glaucoma screening at the primary healthcare level to prevent irreversible damage from glaucoma, which has reached alarmingly high levels particularly in sub-Saharan Africa. Implementing screening programs is necessary and valuable tool for reducing the incidence of glaucoma. Subsequent benefits include the reduction in the prevalence of avoidable blindness caused by POAG; beneficial for public health and overall state welfare, especially in African countries. It is also cost-effective, as it would minimise governments’ financial assistance to grant beneficiaries whilst alleviating the workload on already limited human resources for eye care.