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 .
The Effectiveness of Irlen Filters for Improving Reading Performance: A Pilot Study
The objectives of this pilot study were to investigate the effectiveness of Irlen filters for improving comfort and reading performance and to determine whether traditional optometric intervention would be effective in relieving the symptoms commonly reported by people seeking help through the use of Irlen filters . Thirty subjects were included in the study : 12 males and 18 females . The ages of the subjects ranged from 9 to 51 ( mean = 23.6 ) . They were r and omly placed in either an Irlen filter treatment group ( n = 11 ) , a vision therapy treatment group ( n = 11 ) , or a control group ( n = 8) . Pre- and posttesting on all subjects included a vision evaluation , reading and intelligence testing , the Irlen scotopic sensitivity screening test , and a symptom question naire . Results revealed that subjects in both treatment groups were more comfortable after treatment , although only the vision therapy group showed improvement in vision functioning . The subjects in the Irlen filter group did not show any significant gains in reading rate , word recognition in context , or comprehension
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 .