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 .
Failure of blue-tinted lenses to change reading scores of dyslexic individuals.
BACKGROUND This study was design ed to address a perceived major flaw in past studies investigating tinted lenses and dyslexia ; i.e. , the lack of a direct , scientifically vali date d means of diagnosing the type and severity of dyslexia . METHODS Sixteen 5th and 8th grade students , found to be dyslexic based on testing via the Dyslexia Determination Test ( DDT ) , were r and omly divided into two groups of eight . One group was tested first with blue filters ( then , 2 to 5 weeks later , no filters ) using the Gates MacGinitie Reading Test for reading comprehension . The other group of eight was tested in the same way , first with no filters , then 2 to 5 weeks later with blue filters . The grade level of the test used for each subject was in accord with the DDT decoding level . RESULTS There was no significant difference in reading comprehension level or reading speed when the blue filter condition was compared to the no filter condition . CONCLUSIONS Using DDT classification , subjects were found to have mostly dysphoneidetic ( mixed pattern ) dyslexia . Among this population of dyslexic students , tinted lenses appeared to provide no beneficial effect . We offer an explanation based on neuro-anatomical relationships between the visual system and reading centers in the brain . The hypothesis states that the transient system defect may be an epiphenomenon , which can coincidentally occur in cases of reading disability
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 .