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 .
Coloured Overlays, Text, and Texture
In four studies children were asked to read aloud a passage of r and omly ordered common words with and without a coloured sheet of plastic ( overlay ) placed upon the page . The  children 's rate of reading increased with the overlay , for some children more than for others . The children were also asked to undertake a test of texture segmentation in which targets consisting of a structured texture had to be distinguished from within a r and om background texture . The texture segmentation was improved when the overlay was used , again for some children more than for others . The improvement in texture segmentation was , in general , correlated with the improvement in rate of reading . Slower readers were generally poorer at texture segmentation . The implication s for reading , for texture segmentation , and for clinical tests of vision are discussed
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 .