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 .
The Cochrane Collaboration’s tool for assessing risk of bias in randomised trials
Flaws in the design , conduct , analysis , and reporting of r and omised trials can cause the effect of an intervention to be underestimated or overestimated . The Cochrane Collaboration ’s tool for assessing risk of bias aims to make the process clearer and more
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 .