Methodological quality of the review: Medium confidence
Author: Powell C, Wedner S, Hatt SR.
Region: Details not provided
Sector: Visual acuity
Sub-sector: Screening, visual acuity deficits
Equity focus: School-age children and adolescents
Review type: Effectiveness review
Quantitative synthesis method: Narrative analysis
Qualitative synthesis methods: Not applicable
Reduced vision resulting from refractive error is likely to cause children to screw their eyes and experience headaches. Uncorrected refractive error is also known to be the leading cause of visual impairment among children. This problem may have effect on academic performance and substantially influence socio-economic life. The need to correct refractive error is determined by its effects on vision. Normal vision is most likely to be restored by wearing corrective glasses or contact lenses, but may cause error to persist. Recently, vision screening is widely used. The detection and correction of refractive errors has been made one of the priorities of the WHO initiative Vision 2020. However, the disability caused by a vision deficit has not been quantified and the optimum age and number of occasions for screening have not been explored.
To assess the effectiveness of vision screening programmes among school-age children in schools to reduce the prevalence of undetected, correctable visual acuity deficits due to refractive error.
The authors identified a total of 901 reports of studies. Full text copies were obtained for three papers where no abstract was provided; all three papers were excluded as they were not trials. An additional 528 reports were identified in the first update of this study; none of these were eligible for inclusions and, therefore, till this update no trials evaluating the effectiveness of screening for visual acuity in school-age children had been found.
Authors concluded that there were no robust trials available that allow the benefits of school vision screening to be measured. The disadvantage of attending school with a visual acuity deficit also needed to be quantified. The impact of a screening programme would depend on the geographical and socio-economic setting in which it is conducted. There was, therefore, clearly a need for well-planned randomized controlled trials (RCTs) to be undertaken in various settings so that the potential benefits and harms of vision screening can be measured.
The authors planned to include RCTs or cluster RCTs that screen participants in a school screening programme; screening was carried out by visual acuity (VA) assessment using any age-appropriate vision test; measuring monocular VA or binocular VA or both, distance VA, near and distance VA.
The authors conducted a search in databases including Cochrane Central Register of Controlled Trials (CENTRAL), which contains the Cochrane Eyes and Vision Trials Register, in the Cochrane Library, Medline and Embase from inception until 2006. No restrictions to a specific language or date were applied on the searches.
One author selected all the searched results that met the search criteria; making reference to refractive error, myopia and vision screening. The titles and abstract of the studies were screened by two authors to establish if they meet the inclusion criteria. The authors did not perform any manual searches, however, they suggested that manual searching on conference proceedings would be done in future updates of the review. Again, the authors suggested that in future updates of the article, two authors would independently extract data using Cochrane Eye and Vision group data collection form. No trials met the inclusion criteria and therefore no quality assessment was performed. Authors therefore used narrative synthesis to explain current practice.
This article was not considered applicable as no studies were eligible for inclusion.
The authors did not restrict the search to specific income settings. However, findings may have potentially served the purpose of providing access to health care in low- and middle- income settings due to the scarce of evidence/research in this field.
There is medium confidence in the conclusions about the effects of this study. As the authors did not identify studies meeting the inclusion criteria, a small selection of observational, cross-sectional and cohort studies, which were identified in reference lists, were described in an attempt to explain current practice. The limitation identified, acknowledged by the authors, it was not possible for reviewers to contact researchers in the field for further relevant studies and did not conduct manual searches. Nevertheless, the authors did not draw a strong policy conclusions about the effects of studies included.