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 .
Pattern glare: the effects of contrast and color
Aim : To test a theory of visual stress by investigating the inter-relationships between ( 1 ) the threshold contrast/saturation at which individuals first report discomfort when viewing colored gratings of progressively increasing contrast and decreasing saturation ; ( 2 ) the choice of a colored overlay for reading ; ( 3 ) any increase in reading speed when the overlay is used . Method : Ninety-five young adults , with normal color vision , reported illusions from square-wave gratings ( Pattern Glare Test ) , chose any colored overlays that improved clarity ( Intuitive Color Overlays ) and read aloud r and omly ordered common words ( Wilkins Rate of Reading Test ) . This was followed by an automated choice of tints for text using various screen colors on a tablet , and a test of discomfort from patterns of progressively increasing contrast and decreasing saturation , using software developed for this study . All participants wore their optimal refractive correction throughout the procedure . Results : Fifty-eight participants chose a colored overlay and reported that it made text easier and more comfortable to read . On average , these individuals had a greater improvement in reading speed with their overlays ( p = 0.003 ) , a lower contrast threshold at which discomfort from achromatic gratings was first reported ( p = 0.015 ) , and a tendency to report more pattern glare ( p = 0.052 ) , compared to the other participants . Participants who chose both a most and least preferred tint for text using the automated procedure reported discomfort from colored gratings at a significantly higher contrast with their most preferred color compared to their least preferred color ( p = 0.003 ) . The choice of a colored tint was moderately consistent across tests . The most and least preferred colors tended to be complementary . Conclusion : Colored tints that improved reading speed reduced pattern glare both in terms of the illusion susceptibility and in terms of discomfort contrast threshold , supporting a theory of visual stress . An automated test that incorporates colored gratings and a choice of most and least preferred color might better identify individuals whose reading speed improves with colored overlays
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 .