Vision screening for correctable visual acuity deficits in school-age children and adolescents.

Evans JR, Morjaria P, Powell C.
Cochrane Database Syst Rev. 2018 Feb 15;2:CD005023.

BACKGROUND: Although the benefits of vision screening seem intuitive, the value
of such programmes in junior and senior schools has been questioned. In addition 
there exists a lack of clarity regarding the optimum age for screening and
frequency at which to carry out screening.
OBJECTIVES: To evaluate the effectiveness of vision screening programmes carried 
out in schools to reduce the prevalence of correctable visual acuity deficits due
to refractive error in school-age children.
SEARCH METHODS: We searched the Cochrane Central Register of Controlled Trials
(CENTRAL) (which contains the Cochrane Eyes and Vision Trials Register) (2017,
Issue 4); Ovid MEDLINE; Ovid Embase; the ISRCTN registry; ClinicalTrials.gov and 
the ICTRP. The date of the search was 3 May 2017.
SELECTION CRITERIA: We included randomised controlled trials (RCTs), including
cluster-randomised trials, that compared vision screening with no vision
screening, or compared interventions to improve uptake of spectacles or
efficiency of vision screening.
DATA COLLECTION AND ANALYSIS: Two review authors independently screened search
results and extracted data. Our pre-specified primary outcome was uncorrected, or
suboptimally corrected, visual acuity deficit due to refractive error six months 
after screening. Pre-specified secondary outcomes included visual acuity deficit 
due to refractive error more than six months after screening, visual acuity
deficit due to causes other than refractive error, spectacle wearing, quality of 
life, costs, and adverse effects. We graded the certainty of the evidence using
MAIN RESULTS: We identified seven relevant studies. Five of these studies were
conducted in China with one study in India and one in Tanzania. A total of 9858
children aged between 10 and 18 years were randomised in these studies, 8240 of
whom (84%) were followed up between one and eight months after screening. Overall
we judged the studies to be at low risk of bias. None of these studies compared
vision screening for correctable visual acuity deficits with not screening.Two
studies compared vision screening with the provision of free spectacles versus
vision screening with no provision of free spectacles (prescription only). These 
studies provide high-certainty evidence that vision screening with provision of
free spectacles results in a higher proportion of children wearing spectacles
than if vision screening is accompanied by provision of a prescription only (risk
ratio (RR) 1.60, 95% confidence interval (CI) 1.34 to 1.90; 1092 participants).
The studies suggest that if approximately 250 per 1000 children given vision
screening plus prescription only are wearing spectacles at follow-up (three to
six months) then 400 per 1000 (335 to 475) children would be wearing spectacles
after vision screening and provision of free spectacles. Low-certainty evidence
suggested better educational attainment in children in the free spectacles group 
(adjusted difference 0.11 in standardised mathematics score, 95% CI 0.01 to 0.21,
1 study, 2289 participants). Costs were reported in one study in Tanzania in 2008
and indicated a relatively low cost of screening and spectacle provision
(low-certainty evidence). There was no evidence of any important effect of
provision of free spectacles on uncorrected visual acuity (mean difference -0.02 
logMAR (95% CI adjusted for clustering -0.04 to 0.01) between the groups at
follow-up (moderate-certainty evidence). Other pre-specified outcomes of this
review were not reported.Two studies explored the effect of an educational
intervention in addition to vision screening on spectacle wear. There was
moderate-certainty evidence of little apparent effect of the education
interventions investigated in these studies in addition to vision screening,
compared to vision screening alone for spectacle wearing (RR 1.11, 95% CI 0.95 to
1.31, 1 study, 3177 participants) or related outcome spectacle purchase (odds
ratio (OR) 0.84, 95% CI 0.55 to 1.31, 1 study, 4448 participants). Other
pre-specified outcomes of this review were not reported.Three studies compared
vision screening with ready-made spectacles versus vision screening with
custom-made spectacles. These studies provide moderate-certainty evidence of no
clinically meaningful differences between the two types of spectacles. In one
study, mean logMAR acuity in better and worse eye was similar between groups:
mean difference (MD) better eye 0.03 logMAR, 95% CI 0.01 to 0.05; 414
participants; MD worse eye 0.06 logMAR, 95% CI 0.04 to 0.08; 414 participants).
There was high-certainty evidence of no important difference in spectacle wearing
(RR 0.98, 95% CI 0.91 to 1.05; 1203 participants) between the two groups and
moderate-certainty evidence of no important difference in quality of life between
the two groups (the mean quality-of-life score measured using the National Eye
Institute Refractive Error Quality of Life scale 42 was 1.42 better (1.04 worse
to 3.90 better) in children with ready-made spectacles (1 study of 188
participants). Although none of the studies reported on costs directly,
ready-made spectacles are cheaper and may represent considerable cost-savings for
vision screening programmes in lower income settings. There was low-certainty
evidence of no important difference in adverse effects between the two groups.
Adverse effects were reported in one study and were similar between groups. These
included blurred vision, distorted vision, headache, disorientation, dizziness,
eyestrain and nausea.
AUTHORS' CONCLUSIONS: Vision screening plus provision of free spectacles improves
the number of children who have and wear the spectacles they need compared with
providing a prescription only. This may lead to better educational outcomes.
Health education interventions, as currently devised and tested, do not appear to
improve spectacle wearing in children. In lower-income settings, ready-made
spectacles may provide a useful alternative to expensive custom-made spectacles.