Methodological quality of the review: Medium confidence
Author: Chou R, Dana T, Bougastos C.
Region: Details not provided
Sector: Visual impairment
Equity focus: Children of age one to five years
Review type: Effectiveness review
Quantitative synthesis method: Narrative analysis
Qualitative synthesis method: Not applicable
The effect of visual impairment in young children is manifold. Visual impairment can reduce quality of life and school performance. Visual impairment among preschool-aged children in the USA is commonly linked to amblyopia, strabismus and refractive errors. Amblyopia-related visual impairment is not corrected immediately with refractive lenses. Similarly, strabismus can hinder development of normal binocular vision and result in psycho-social consequences. Vision screening among preschool-aged children that includes a measurement of visual acuity is likely to help identify children who might benefit from early interventions.
To determine the effectiveness of screening preschool-aged children for impaired visual acuity on health outcomes.
The authors included 65 studies that met the inclusion criteria and answered the six key research questions proposed for the study. However, no study was found that explained the accuracy/reliability of risk factor assessment. Out of these, one randomized control trial (RCT), one prospective cohort study and three retrospective cohort studies evaluated screening outcomes; one RCT and one retrospective cohort study evaluated variation in age groups; 31 diagnostic accuracy studies evaluated accuracy of screening tests; four studies addressed variation in age, one cohort study and seven false positive studies evaluated harms of screening; eight RCTs assessed the effectiveness of treatment; five RCTs focusing on non-amblyopic eye visual and acuity evaluated harms of treatment.
The authors included studies that focused on screening, diagnosis and treatment of visual impairment in children one to five years of age; randomized trials and controlled observational studies on preschool.
The authors conducted a search in databases including Ovid Medline, Cochrane Central Register of Controlled Trails and the Cochrane Database of Systematic Review from inception to 2009. The search included a number of terms associated with screening, diagnosis and treatment of visual impairment. The electronic searches were also supplemented by reviews of reference list and by consulting experts. The review was limited to available English language studies.
Two authors abstracted and evaluated each study for inclusion. The methodological quality was assessed using the USPSTF criteria taking into consideration the internal validity and graded each study as good, fail or poor. Any discrepancies were resolved by discussion and consensus.
The authors conducted a sensitivity, specificity and likelihood ratio test for diagnostic accuracy studies using diagti procedure in Stata 10. Due to differences in populations, screening cutoffs applied and between study heterogeneity in results, the review did not pool test for diagnostic accuracy studies. Also, the trials of treatment in the study were too few to perform meta-analysis.
The study evaluated the applicability of findings to population likely to be encountered in the primary care screening settings on the basis of recruitment from a primary care setting. However, studies that evaluated diagnostic accuracy of screening in a community setting could limit their applicability to the primary care settings.
The authors did not restrict the search to specific income settings. Studies included originated from the UK, Canada, USA, Sweden, Israel, Germany, Australia, New Zealand and China which was not specified by the authors. However, findings may serve the purpose of providing access to eye health care in low- and middle-income settings due to the scarce of evidence/research findings in this field.
Overall, there is medium confidence in the conclusions about the effects of this study. The search strategy was based on relevant databases, reference lists of included studies and contacting experts/authors for potentially relevant studies. However, reviewers did not avoid language bias and restricted the search to published trials. Additionally, although two authors conducted study selection, it is not clear if this was conducted independently. Nevertheless, authors acknowledged study limitations and did not draw strong policy conclusions.