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 .
Prolonged use of coloured overlays for classroom reading.
Ninety-three children in a primary school and 59 children in two first-year classes of a secondary school were asked individually to observe a paragraph of r and om letters arranged to resemble text , and to compare the perceptual effects on its clarity of coloured plastic sheets overlaid on the text . A total of 29 colours were compared using 10 coloured plastic sheets and 19 pairwise combinations of sheets , one superimposed on another . The result ing colours sample d CIE 1976 hue angle ( huv ) and saturation ( suv ) systematic ally and efficiently . All the children who reported beneficial perceptual effects ( 53 per cent ) were given their preferred overlay or combination of overlays to use as and when they wished . When the children were examined three months later the children tended to choose a colour similar to one they had chosen previously . Ten months later , 22 per cent of those offered the overlaps were still using them of their own volition . These children , but not those who had ceased to use their overlay(s ) , read r and omly ordered simple words more quickly with their overlay than without . In a second independent group of children referred to the Norfolk Sensory Support Service , who used overlays routinely , the reading speed was similar with a grey or clear overlay ; and slower than with the chosen coloured overlay , suggesting that reduction of contrast was not the critical factor . In a third independent group of children in a primary school in Kent , the increase in reading speed with the chosen overlay predicted the children who continued to use their overlay during the ensuing eight weeks
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 .