Methodological quality of the review: Low confidence

Author: Sharma A, Congdon N, Patel M, Gilbert C.

Region: Mexico, Tanzania, China, United Stated of America (USA), Sweden, United Kingdom (UK) and India

Sector: Refractive error

Sub-sector: Children, education, school, prevalence

Equity focus: Children aged up to 15 years

Review type: Effectiveness review

Quantitative synthesis method: Narrative analysis

Qualitative synthesis methods: Not applicable

Background

Globally, refractive errors have been identified as the leading cause of blindness among all age groups after cataract and the leading cause of visual impairment. The World Health Organization (WHO) estimated that around 13 million children aged five to 15 years worldwide are visually impaired from uncorrected refractive error. Despite this, there seems to be limited provision of spectacles or optical corrections among most of the adults and children with refractive error around the world. School vision screening programmes can identify and treat or refer children with refractive error.

Research objectives

To provide the evidence base for programme planners and managers seeking the best strategies for providing sustainable services for children, acknowledging that priorities, available resources, and the context vary from location to location.

Main findings

The authors included 44 articles in the review; the review stated that randomized trials were included, however the authors also mentioned reviewing original and review articles to answer the research question. Therefore, it was not clear which study designs were included in the review.

Included studies reported findings of various screening studies and attempted to identify key factors in the success and sustainability of such programmes.

The authors reported the following results:

‘Inadequately corrected refractive error is an important global cause of visual impairment in childhood. School-based vision screening carried out by teachers and other ancillary personnel may be an effective means of detecting affected children and improving their visual function with spectacles. The need for services and potential impact of school-based programmes varies widely between areas, depending on prevalence of refractive error and competing conditions and rates of school attendance. Barriers to acceptance of services include the cost and quality of available refractive care and mistaken beliefs that glasses will harm children’s eyes. Further research is needed in areas such as the cost-effectiveness of different screening approaches and impact of education to promote acceptance of spectacle-wear. School vision programmes should be integrated into comprehensive efforts to promote healthy children and their families.’

Methodology

The authors included randomized trials and excluded studies that enrolled fewer than 50 subjects, as well as studies concerned primarily with technologies for refractive screening, but without significant programmatic information. Although the authors reported including all randomized trials, it is not clear what other study designs were included in the review.

A search of Pubmed, Medline, OVID, Google Scholar, and Oxford University Electronic Resources Databases was conducted independently by two authors between April and May 2010 using the following key words and MeSH terms: refractive error, visual acuity, spectacles, refraction, mydriatic, quality, screening, programme evaluations, barrier, costs, child, school, teacher, nurse, assistant, and optometrist. The searches were limited to English and human studies, covering the years 1990 to 2010. In-depth analysis of 230 articles and 12 reviews was conducted by two reviewers, and 44 articles were selected for use in this review. Additional studies were obtained from literature referenced in the original set of articles.

All included articles  were assessed by identifying and extracting the following data: purpose of the study, study design, setting, participants characteristics, outcomes (accuracy of screening, quality of refractive services, acceptance of services, barriers to uptake, improvement of quality of life, and cost and cost-effectiveness of programmes.

The authors conducted a narrative synthesis of the included studies, which was appropriate for the purpose of this review.

Applicability/external validity

The authors did not generalize the results as the outcomes reported differed between countries.

Geographic focus

The authors did not report the setting for all included studies. Countries included Mexico, Tanzania, China, the USA, Sweden, UK and India. The authors reported that prevalence of refractive error varied between countries, and for example in India and China, varied between rural and urban populations. Nevertheless, in all the studies, the prevalence of hypermetropia declined with age; astigmatism was fairly constant across the age range, whereas myopia increased with age. Other outcomes measured, including the effectiveness of using screening charts and rates of utilization of spectacles, varied significantly between countries.

Quality assessment

Overall, there is low confidence in the conclusions about the effects of this review. Although the authors did not draw strong conclusions from findings, the literature search was not comprehensive enough that we can be confident that relevant studies were not omitted in the review. Additionally, risk of bias was not avoided on the methods used to select studies and extract data of included studies; and the authors did not report assessing the quality and risk of bias of included studies. Therefore, we cannot be confident that findings were not reliably reported impacting on the overall validity of the review.