Both coloured overlays and coloured lenses can improve reading fluency, but their optimal chromaticities differ. Randomised controlled trial of the effect of coloured overlays on the rate of reading of people with specific learning difficulties. Reading Disabilities and the Effects of Colored Filters Colored overlays for visual perceptual deficits in children with reading disability and attention deficit/hyperactivity disorder: are they differentially effective? The effects of coloured light filter overlays on reading rates in age-related macular degeneration. Rate of Reading Test: its reliability, and its validity in the assessment of the effects of coloured overlays. Benefit of coloured lenses for age-related macular degeneration. Double-masked placebo-controlled trial of precision spectral filters in children who use coloured overlays. Pattern-related visual stress, chromaticity, and accommodation. Effect of variable tinted spectacle lenses on visual performance in control subjects. Parents' and Children's Expectations about Irlen (Tinted) Lenses Effects of wearing yellow spectacles on visual skills, reading speed, and visual symptoms in children with reading difficulties Prolonged use of coloured overlays for classroom reading. Application of ChromaGen haploscopic lenses to patients with dyslexia: a double-masked, placebo-controlled trial. Coloured Overlays, Text, and Texture A comparison of two-coloured filter systems for treating visual reading difficulties Failure of blue-tinted lenses to change reading scores of dyslexic individuals.
Some individuals read more fluently when the text is coloured : i.e. , when coloured sheets of plastic ( overlays ) are placed upon the page , or when coloured lenses are worn . Overlays provide a surface colour whereas lenses mimic a change in the colour of a light source . The neural mechanisms that underlie colour constancy ensure that the chromaticity of overlays and lenses is processed differently by the visual system . We investigated ( 1 ) the relationship between the optimal colours of overlays and lenses , and ( 2 ) how reading rate is affected by a particular colour in overlays and lenses .  In 100 patients we noted ( 1 ) the overlay(s ) chosen from among the 29 combinations of the 10 IOO Intuitive Overlays which sample chromaticity systematic ally and ( 2 ) the chromaticity co-ordinates of the lenses subsequently chosen using the intuitive Colorimeter , a device providing a light source that can be adjusted in hue , saturation and luminance independently . The relationship between the chromaticities of the overlays and the lenses showed considerable variation . In a second study , patients attending the Specific Learning Difficulties clinic at the Institute of Optometry , London , were given overlays to use for two months . Seventeen who derived benefit were examined using the  Intuitive Colorimeter .  Patients were asked to read aloud r and omly ordered common words ( Wilkins Rate of Reading Test ) : ( 1 ) with no colour , ( 2 ) with the chosen overlay , ( 3 ) with lenses matching the chosen overlay and ( 4 ) with lenses matching the Colorimeter setting . The aids increased reading rate significantly only in conditions ( 2 ) and ( 4 ) . There was no significant improvement when lenses matching the overlay colour were used , and under this condition the reading rate was significantly poorer than in conditions ( 2 ) and ( 4 ) . The colour of a lens will improve reading only if it is selected under conditions that mimic a change in the colour of a light source : coloured overlays give no clinical ly reliable guide to optimal lens colour A r and omised controlled trial has demonstrated that , for selected children with reading difficulties , individually prescribed coloured filters reduce symptoms of asthenopia . In the present study , we investigate the effect of individually prescribed coloured overlays on the rate of reading .  Subjects were 33 children and adults who : had consulted a specific learning difficulties clinic ; had received treatment to normalise any conventional optometric and orthoptic anomalies ; and subsequently reported symptomatic relief from coloured filters .  These subjects carried out the Wilkins Rate of Reading Test ( which assesses visual rather than linguistic factors ) under two conditions : with their chosen coloured overlay and with a control filter . Steps were taken to ensure that a strong placebo effect was associated with the control overlay and , when asked which they preferred , subjects were not significantly more likely to prefer their coloured overlay than the control filter ( p=0.11 ) . Nonetheless , the rate of reading was significantly faster with the coloured overlay than with the control ( p=0.0019 ) . Further analyses support the conclusion that individually prescribed coloured filters can improve reading performance for reasons that can not be solely attributed to conventional optometric factors or to placebo effects The efficacy of a controversial treatment , using colored filters to remediate reading disabilities , was measured empirically , with colored overlays placed over reading material on white paper . Irlen 's ( 1983 ) method is to prescribe specific tinted filters as lenses that she cl aims filter specific light frequencies and remove a range of perceptual disorders that adversely affect reading and related learning performance . Irlen calls this condition " scotopic sensitivity " and cl aims it is a significant factor in a high percentage of people with learning disabilities . Ninety-two children with significant reading disabilities were classified as either scotopic or nonscotopic using the Irlen Differential Perceptual Schedule , and were r and omly assigned to one of six treatment groups using colored or clear overlays .  Reading performance ( rate , accuracy , and comprehension ) as measured by the Neale Analysis of Reading Ability ( Neale , 1987 ) and the Formal Reading Inventory ( Wiederholt , 1986 ) improved significantly when the scotopic children read with the preferred colored overlay filter compared to clear or different-colored overlay filters . Nonscotopic children showed no change The Transient Channel Deficit ( TCD ) model of reading disability was evaluated by examining the effects of color overlays on the reading ability of four groups of children ( n = 15 each ) with reading disability and comorbid conditions involving math and ADHD . These 60 children were evaluated for reading accuracy and rate on measures of word decoding and reading comprehension under three color transparency conditions ( blue , red , no overlay ) . Results indicated that color overlays did not differentially affect the reading performance of individuals with and without reading disabilities . However , blue transparencies significantly improved reading comprehension in all groups , and reduced reading rate . These findings indicate that the TCD model may need to be reexamined . An alternative hypothesis for the observed effects , involving facilitation of attention processes , was posted PURPOSE To determine the effect of coloured light filter overlays on reading rates for people with age-related macular degeneration ( AMD ) . METHOD Using a prospect i ve clinical trial design , we examined the null hypothesis that coloured light filter overlays do not improve reading rates in AMD when compared to a clear filter .  Reading rates for 12 subjects with non-exudative AMD , associated with a relative scotoma and central fixation ( mean age 81 years , SD 5.07 years ) were determined using the Rate of Reading Test ( printed , nonsense , lower case sans serif , stationary text ) with 10 different , coloured light filter overlays ( Intuitive Overlays ) ; figures in brackets are percentage transmission values ) ; rose ( 78 % ) , pink ( 78 % ) , purple ( 67 % ) , aqua ( 81 % ) , blue ( 74 % ) , lime-green ( 86 % ) , mint-green ( 85 % ) , yellow ( 93 % ) , orange ( 83 % ) and grey ( 71 % ) . A clear overlay ( Roscolene # 00 ) ( 360 cdm-2 ) with 100 % transmittance was used as a control . RESULTS Anova indicated that there was no statistically significant difference in reading rates with the coloured light filter overlays compared to the clear filter . Furthermore , chi-squared analysis indicated that the rose , purple and blue filters had a significantly poorer overall ranking in terms of reading rates compared to the other coloured and clear light filters . CONCLUSION Coloured light filter overlays are unlikely to provide a clinical ly significant improvement in reading rates for people with non-exudative AMD associated with a relative scotoma and central fixation A simple reading test that can be undertaken by disabled readers is described . The test is suitable for use in the optometric clinic , taking less than 2 minutes to administer per passage . Test-retest scores are acceptably reliable . The test reveals increases in the speed of reading when coloured overlays are used both ( 1 ) in children who have made long-term use of coloured overlays for reading , and ( 2 ) in children who will subsequently do so PURPOSE To evaluate and compare the functional and perceived benefits of wearing coloured lenses by patients with age-related macular degeneration ( ARMD ) . METHOD Ten subjects with early ARMD and five elderly controls wore a selection of NoIR wrap-around coloured lenses ( yellow 29.7 % light transmission , orange 22.9 % , red 16.8 % and grey 10.3 % ) , each for a duration of 7 days . Contrast sensitivity , colour vision , visual acuity , the effect of glare and peripheral sensitivity were measured for each lens and compared with a control ( no lens ) condition . Subjective ratings of visual performance were also scored . RESULTS Compared with the no filter condition , red and grey lenses reduced contrast sensitivity whereas yellow and orange lenses increased contrast sensitivity . These objective changes were supported by subjective ratings in subjects with ARMD . Grey lenses reduced the loss of contrast sensitivity usually suffered in the presence of glare , whereas visual acuity and peripheral sensitivity decreased with red lenses . Colour vision became distorted with red lenses in control subjects , but was relatively unaffected by the use of coloured lenses in subjects with ARMD . CONCLUSIONS The subjective benefit of coloured lenses appears to be due to a minor enhancement of contrast sensitivity We selected 68 children who reported benefit from individually chosen sheets of coloured plastic placed upon the page when reading , and who used these regularly without prompting . These children viewed text illuminated by coloured light in an apparatus that allowed the separate manipulation of hue ( colour ) and saturation ( depth of colour ) , at constant luminance . Many of the children reported improvements in perception when the light had a chromaticity within a limited range , which was different for each individual . A pair of plastic spectacle lenses ( ' experimental ' lenses ) was dyed so as to provide the appropriate chromaticity under conventional white ( F3 ) fluorescent light . An additional pair was prepared having very similar colour but with a chromaticity outside the range in which perception was reported to improve ( ' control ' lenses ) . Each pair was provided for 1 month in r and om order . The children kept diaries ( 36 completed ) recording symptoms of eye-strain and headache . The children and those responsible for their assessment were unable reliably to distinguish ' experimental ' from ' control ' lenses . Nevertheless , symptoms were less frequent on days when the ' experimental ' lenses were worn ( P < 0.003 ) 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 PURPOSE To evaluate quantitatively the effects of tinted spectacle lenses on visual performance in individuals without visual pathology . METHODS Twenty-five subjects were assessed by measuring contrast sensitivity with and without glare . Gray , brown , yellow , green , purple , and blue lens tints were evaluated . Measurements were repeated with each lens tint and with a clear lens , and the order was counterbalanced within and between subjects . Glare was induced with a modified brightness acuity tester . RESULTS All subjects demonstrated an increase in contrast thresholds under glare conditions for all lens tints . However , purple and blue lens tints result ed in the least amount of contrast threshold increase ; the yellow lens tint result ed in the largest contrast threshold increase . CONCLUSIONS Purple and blue lens tints may improve contrast sensitivity in control subjects under glare conditions Additional unpublished data are presented from a study by Cotton and Evans in 1990 on the use of Irlen ( tinted ) lenses as an intervention for 22 children with a reading disability . These data reinforce rhe earlier conclusion that the r and om facilitatory effects of the lenses are very likely attributional and motivational in nature Background Possible beneficial effects of yellow-tinted spectacle lenses on binocular vision , accommodation , oculomotor scanning , reading speed and visual symptoms were assessed in children with reading difficulties . Methods A longitudinal prospect i ve study was performed in 82 non-dyslexic children with reading difficulties in grade s 3–6 ( aged 9–11 years ) from 11 elementary schools in Madrid ( Spain ) . The children were r and omly assigned to two groups : a treatment ( n = 46 ) and a without-treatment group ( n = 36 ) . Children in the treatment group wore yellow spectacle lenses with best correction if necessary over 3 months ( in school and at home ) . The tests were first undertaken without the yellow filter . With best spectacle correction in each subject , measurements were made of : distance and near horizontal heterophoria , distance and near horizontal fusional vergence ranges , the accommodative convergence/accommodation ( AC/A ) ratio , near point of convergence ( NPC ) , stereoacuity , negative relative accommodation ( NRA ) and positive relative accommodation ( PRA ) , monocular accommodative amplitude ( MAA ) , binocular accommodative facility ( BAF ) , oculomotor scanning , and reading speed ( words per minute ) . The Convergence Insufficiency Symptom Survey ( CISS ) question naire was completed by all children . After the 3-month period , measurements were repeated with the yellow lenses ( treatment group ) or without the yellow lenses ( without-treatment group ) but with refractive correction if needed . Results Over the 3 months , the two groups showed similar mean changes in the variables used to assess binocular vision , accommodation , oculomotor scanning , and reading speed . However , mean relative changes in convergence insufficiency symptoms differed significantly between the groups ( p = 0.01 ) . Conclusion No effects of wearing yellow spectacles emerged on binocular vision , accommodation , oculomotor scanning , and reading speed in children with reading difficulties . The yellow filter had no effect even in children with low MAA and BAF . The reduction in visual symptoms observed in children with reading difficulties using the yellow filters was clinical ly insignificant Ninety-three children in a primary school and 59 children in two first-year classes of a secondary school were asked individually to observe a paragraph of r and om letters arranged to resemble text , and to compare the perceptual effects on its clarity of coloured plastic sheets overlaid on the text . A total of 29 colours were compared using 10 coloured plastic sheets and 19 pairwise combinations of sheets , one superimposed on another . The result ing colours sample d CIE 1976 hue angle ( huv ) and saturation ( suv ) systematic ally and efficiently . All the children who reported beneficial perceptual effects ( 53 per cent ) were given their preferred overlay or combination of overlays to use as and when they wished . When the children were examined three months later the children tended to choose a colour similar to one they had chosen previously . Ten months later , 22 per cent of those offered the overlaps were still using them of their own volition . These children , but not those who had ceased to use their overlay(s ) , read r and omly ordered simple words more quickly with their overlay than without . In a second independent group of children referred to the Norfolk Sensory Support Service , who used overlays routinely , the reading speed was similar with a grey or clear overlay ; and slower than with the chosen coloured overlay , suggesting that reduction of contrast was not the critical factor . In a third independent group of children in a primary school in Kent , the increase in reading speed with the chosen overlay predicted the children who continued to use their overlay during the ensuing eight weeks BACKGROUND Many patients with dyslexia report distortion to text when they are reading . After a successful pilot trial of an improvement in reading rate using ChromaGen haploscopic filters in comparison with the Intuitive Colorimeter , a full-scale , r and omized , cross-over , double-masked , placebo-based trial was undertaken . METHOD The Wilkins rate of reading test was used to produce a baseline score , against which scores with ChromaGen lenses , placebo lenses , and a control were compared .  Exclusion criteria included no formal dyslexia diagnosis , contraindications to contact lens wear , and uncorrected visual causes for reading difficulty . RESULTS Forty-seven individuals successfully completed the trial , of which 41 reported distortion to the text ( e.g. , words appeared to move , were blurred , or patterns or spaces seemed to form in the text ) when the patients were reading , and nine were color deficient . A comparison trial of ChromaGen lenses with placebo lenses demonstrated a significant improvement in the reading rate with ChromaGen lenses in individuals who reported distortion to text ( p = 0.05 ) and a highly significant improvement in non-color-deficient individuals who reported distortion ( p = 0.006 ) . T-tests of the repeated measures showed that ChromaGen lenses produced a highly significant improvement in the rate of reading -- over and above the placebo -- in non-color-deficient individuals who reported distortion ( p < 0.0001 ) . CONCLUSION The significant increase in the reading rate amongst those who reported distortion suggests that by decreasing the distortion to text , a substantial proportion of dyslexic patients --in combination with their normal reading programs -- would benefit from this aid In four studies children were asked to read aloud a passage of r and omly ordered common words with and without a coloured sheet of plastic ( overlay ) placed upon the page . The  children 's rate of reading increased with the overlay , for some children more than for others . The children were also asked to undertake a test of texture segmentation in which targets consisting of a structured texture had to be distinguished from within a r and om background texture . The texture segmentation was improved when the overlay was used , again for some children more than for others . The improvement in texture segmentation was , in general , correlated with the improvement in rate of reading . Slower readers were generally poorer at texture segmentation . The implication s for reading , for texture segmentation , and for clinical tests of vision are discussed Abstract Purpose : Visual disturbances that make it difficult to read text are often termed “ visual stress ” . Coloured filters in spectacles may help some children overcome reading problems that are often caused by visual stress . It has been suggested that for optimal effect each child requires an individually prescribed colour for each eye , as determined in systems such as the “ Harris Foundation ” coloured filters . Alternatively , it has been argued that only blue or yellow filters , as used in the “ Dyslexia Research Trust ” ( DRT ) filter system , are necessary to affect the underlying physiology . Method : A r and omised , double blind trial with 73 delayed readers , was undertaken to compare changes in reading and spelling as well as irregular and non-word reading skills after 3 months of wearing either the Harris or the DRT filters . Results : Reading improved significantly after wearing either type of filter ( t = −8.4 , p < 0.01 ) , with 40 % of the children improving their reading age by 6 months or more during the 3 month trial . However , spelling ability ( t = 2.1 , p = 0.05 ) and non-word reading ( f = 4.7 , p < 0.05 ) improved significantly more with the DRT than with the Harris filters . Conclusion : Education and rehabilitation professionals should therefore , consider coloured filters as an effective intervention for delayed readers experiencing visual stress . Implication s for Rehabilitation Any disability that impacts on a child ’s capacity to read has serious implication s for academic development as well as the ability to participate independently in activities of daily living . One reading disability , generally termed “ visual stress ” , is related to visual disturbances that make it difficult to read text . This research demonstrates the beneficial use of coloured filters for promoting visual reading capacity for children with visual stress . Professionals who are involved in the needs of children with reading delay , may like to consider the benefits that coloured filters can afford children with visual reading problems 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 .