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 .
Double-masked placebo-controlled trial of precision spectral filters in children who use coloured overlays.
We selected 68 children who reported benefit from individually chosen sheets of coloured plastic placed upon the page when reading , and who used these regularly without prompting . These children viewed text illuminated by coloured light in an apparatus that allowed the separate manipulation of hue ( colour ) and saturation ( depth of colour ) , at constant luminance . Many of the children reported improvements in perception when the light had a chromaticity within a limited range , which was different for each individual . A pair of plastic spectacle lenses ( ' experimental ' lenses ) was dyed so as to provide the appropriate chromaticity under conventional white ( F3 ) fluorescent light . An additional pair was prepared having very similar colour but with a chromaticity outside the range in which perception was reported to improve ( ' control ' lenses ) . Each pair was provided for 1 month in r and om order . The children kept diaries ( 36 completed ) recording symptoms of eye-strain and headache . The children and those responsible for their assessment were unable reliably to distinguish ' experimental ' from ' control ' lenses . Nevertheless , symptoms were less frequent on days when the ' experimental ' lenses were worn ( P < 0.003 )
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 .