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 .
Using coloured filters to reduce the symptoms of visual stress in children with reading delay
Abstract Background : Meares Irlen Syndrome ( MIS ) , otherwise known as “ visual stress ” , is one condition that can cause difficulties with reading . Aim : This study aim ed to compare the effect of two coloured-filter systems on the symptoms of visual stress in children with reading delay . Methods : The study design was a pre-test , post-test , r and omized head-to-head comparison of two filter systems on the symptoms of visual stress in school children . A total of 68 UK mainstream schoolchildren with significant impairment in reading ability completed the study . Results : The filter systems appeared to have a large effect on the reported symptoms between pre and post three-month time points ( d = 2.5 , r = 0.78 ) . Both filter types appeared to have large effects ( Harris d = 1.79 , r = 0.69 and DRT d = 3.22 , r = 0.85 ) . Importantly , 35 % of participants ’ reported that their symptoms had resolved completely ; 72 % of the 68 children appeared to gain improvements in three or more visual stress symptoms . Conclusion and significance : The reduction in symptoms , which appeared to be brought about by the use of coloured filters , eased the visual discomfort experienced by these children when reading . This type of intervention therefore has the potential to facilitate occupational engagement
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 .