Comment: The quality of evidence is downgraded by imprecision.
A Cochrane review [Abstract] 1 included 10 trials of multi-component assessment with a total of 10,608 participants. Length of follow-up ranged from one to five years.
Seven trials compared vision screening as part of a multi-component screening versus no screening. Six of these studies used self-reported vision as both screening tool and outcome measure, but did not directly measure vision. One study used a combination of self-reported vision and visual acuity measurement: participants reporting vision problems at screening were treated by the attending doctor, referred to an eye care specialist or given information about resources that were available to assist with poor vision. There was a similar risk of "not seeing well" at follow-up in people screened compared with people not screened in meta-analysis of six studies (RR 1.05, 95%, CI 0.97 to 1.14, n=4522). One trial reported "improvement in vision" and this occurred slightly less frequently in the screened group (RR 0.85, 95% CI 0.52 to 1.40, n=230).
Two trials compared vision screening (visual acuity testing) alone with no vision screening. In one study, distance visual acuity was similar in the two groups at follow-up (MD 0.02 logMAR, 95% CI −0.02 to 0.05, n=532). There was also little difference in near acuity (MD 0.02 logMAR, 95% CI −0.03 to 0.07). The other study could not be included in the data analysis.
One trial compared a detailed health assessment including measurement of visual acuity (intervention) with a brief health assessment including one question about vision (standard care). People given the detailed health assessment had a similar risk of visual impairment (visual acuity worse than 6/18 in either eye) at follow-up compared with people given the brief assessment (RR 1.07, 95% CI 0.84 to 1.36, n=1807).
Comment by reviewer: Results from community surveys in the over 75 age group (Wormand 1992, Klein 1991) suggest that over half the visual impairment in this age group could potentially be reduced with treatment, notably by cataract surgery or refractive correction. In light of this, the lack of improvement seen in these trials is somewhat surprising, although a screening procedure alone would not be expected to lead to improvements in vision. All studies within this review included participants who were independent and living in the community and several studies specifically excluded participants who lived in residential or nursing care. Therefore participants in these studies were likely to be able to independently seek ophthalmic intervention should they see a need to do so. The authors note that individuals who reported visual problems when prompted to do so in a screening programme may not have perceived their previously unreported visual impairment as a 'need' for intervention.
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