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-related visual stress, chromaticity, and accommodation.
PURPOSE To investigate the impact of colored overlays on the accommodative response of individuals , with and without pattern-related visual stress ( PRVS ) , a condition in which individuals manifest symptoms of perceptual distortion and discomfort when viewing a 3-cyc/deg square-wave grating . METHODS Under double-masked conditions , 11 individuals who reported PRVS selected an overlay with a color individually chosen to reduce perceptual distortion of text and maximize comfort ( PRVS group ) . Two groups of control subjects individually matched for age , sex , and refractive error were recruited . Control group 1 similarly chose an overlay to maximize comfort . Control group 2 used the same overlays as the paired PRVS participant . The overlay improved reading speed by 10 % ( P < 0.001 ) , but only in the PRVS group . A remote eccentric photorefractor was used to record accommodative lag while participants viewed a cross on a background . The background was uniform or contained a grating and was either gray or had a chromaticity identical with that of the chosen overlay . There were therefore four background s in all . RESULTS Overall , the accommodative lag was 0.44 D greater in the participants with PRVS . When the background had the chosen chromaticity , the accommodative lag was reduced by an average of 0.16 D ( P = 0.03 ) in the PRVS group , but not in the symptom-free groups : in control group 2 the colored background slightly increased the accommodative lag . CONCLUSIONS Accommodative lag was greater in individuals susceptible to pattern-related visual stress and was reduced by a colored background
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 .