While many studies report improvements with coloured lenses , the effect size is generally small and /or similar to the improvement found with a placebo condition .
Consistent with previous review s and advice from several professional bodies , we conclude that the use of coloured lenses or overlays to ameliorate reading difficulties can not be endorsed and that any benefits reported by individuals in clinical setting s are likely to be the result of placebo , practice or Hawthorne effects
PURPOSE There are many anecdotal cl aims and research reports that coloured lenses and overlays improve  reading performance .
Here we present the results of a systematic review of this literature and examine the quality of the evidence .
Randomised controlled trial of the effect of coloured overlays on the rate of reading of people with specific learning difficulties.
A r and omised controlled trial has demonstrated that , for selected children with reading difficulties , individually prescribed coloured filters reduce symptoms of asthenopia . In the present study , we investigate the effect of individually prescribed coloured overlays on the rate of reading .  Subjects were 33 children and adults who : had consulted a specific learning difficulties clinic ; had received treatment to normalise any conventional optometric and orthoptic anomalies ; and subsequently reported symptomatic relief from coloured filters .  These subjects carried out the Wilkins Rate of Reading Test ( which assesses visual rather than linguistic factors ) under two conditions : with their chosen coloured overlay and with a control filter . Steps were taken to ensure that a strong placebo effect was associated with the control overlay and , when asked which they preferred , subjects were not significantly more likely to prefer their coloured overlay than the control filter ( p=0.11 ) . Nonetheless , the rate of reading was significantly faster with the coloured overlay than with the control ( p=0.0019 ) . Further analyses support the conclusion that individually prescribed coloured filters can improve reading performance for reasons that can not be solely attributed to conventional optometric factors or to placebo effects
While many studies report improvements with coloured lenses , the effect size is generally small and /or similar to the improvement found with a placebo condition .
Consistent with previous review s and advice from several professional bodies , we conclude that the use of coloured lenses or overlays to ameliorate reading difficulties can not be endorsed and that any benefits reported by individuals in clinical setting s are likely to be the result of placebo , practice or Hawthorne effects
PURPOSE There are many anecdotal cl aims and research reports that coloured lenses and overlays improve  reading performance .
Here we present the results of a systematic review of this literature and examine the quality of the evidence .