title: Parents' and Children's Expectations about Irlen (Tinted) Lenses The Method Quality of Cross-Over Studies Involved in Cochrane Systematic Reviews Likelihood of Null Effects of Large NHLBI Clinical Trials Has Increased over Time Pattern glare: the effects of contrast and color The Cochrane Collaboration’s tool for assessing risk of bias in randomised trials A comparison of two-coloured filter systems for treating visual reading difficulties Pattern-related visual stress, chromaticity, and accommodation. The Hawthorne Effect: a randomised, controlled trial Both coloured overlays and coloured lenses can improve reading fluency, but their optimal chromaticities differ. Rate of Reading Test: its reliability, and its validity in the assessment of the effects of coloured overlays. Prolonged use of coloured overlays for classroom reading. Reading Disabilities and the Effects of Colored Filters Effects of wearing yellow spectacles on visual skills, reading speed, and visual symptoms in children with reading difficulties Double-masked placebo-controlled trial of precision spectral filters in children who use coloured overlays. Failure of blue-tinted lenses to change reading scores of dyslexic individuals. Randomised controlled trial of the effect of coloured overlays on the rate of reading of people with specific learning difficulties. Application of ChromaGen haploscopic lenses to patients with dyslexia: a double-masked, placebo-controlled trial. Scotopic Sensitivity/Irlen Syndrome and the Use of Coloured Filters: A Long-Term Placebo-Controlled Study of Reading Strategies Using Analysis of Miscue Scotopic Sensitivity/Irlen Syndrome and the Use of Coloured Filters: A Long-Term Placebo Controlled and Masked Study of Reading Achievement and Perception of Ability The Effectiveness of Irlen Filters for Improving Reading Performance: A Pilot Study Coloured Overlays, Text, and Texture The Role of Attributional Bias and Visual Stress on the Improvement of Reading Speed Using Colored Filters Computerized screening for visual stress in children with dyslexia. Bias in randomised controlled trials: comparison of crossover group and parallel group designs Colored overlays for visual perceptual deficits in children with reading disability and attention deficit/hyperactivity disorder: are they differentially effective? Using coloured filters to reduce the symptoms of visual stress in children with reading delay
abstract: Additional unpublished data are presented from a study by Cotton and Evans in 1990 on the use of Irlen ( tinted ) lenses as an intervention for 22 children with a reading disability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 It is possible that cross-over studies included in current systematic review s are being inadequately assessed , because the current risk of bias tools do not consider possible biases specific to cross-over design . We performed this study to evaluate whether this was being done in  cross-over studies included in Cochrane  Systematic Review s ( CSRs ) . Methods We search ed the Cochrane Library ( up to 2013 issue 5 ) for CSRs that included at least one cross-over trial . Two authors independently undertook the study selection and data extraction . A r and om sample of the CSRs was selected and we evaluated whether the cross-over trials in these CSRs were assessed according to criteria suggested by the Cochrane h and book . In addition we reassessed the risk of bias of these cross-over trials by a checklist developed form the Cochrane h and book . Results We identified 688 CSRs that included one or more cross-over studies . We chose a r and om sample of 60 CSRs and these included 139 cross-over studies . None of these CSRs undertook a risk of bias assessment specific for cross-over studies . In fact items specific for cross-over studies were seldom considered anywhere in quality assessment of these CSRs . When we reassessed the risk of bias , including the 3 items specific to cross-over trials , of these 139 studies , a low risk of bias was judged for appropriate cross-over design in 110(79 % ) , carry-over effects in 48(34 % ) and for reporting data in all stages of the trial in 114(82 % ) . Assessment of biases in cross-over trials could affect the GRADE assessment of a review ’s findings . Conclusion The current Cochrane risk of bias tool is not adequate to assess cross-over studies . Items specific to cross-over trials leading to potential risk of bias are generally neglected in CSRs . A proposed check list for the evaluation of cross-over trials is provided Background We explore whether the number of null results in large National Heart Lung , and Blood Institute ( NHLBI ) funded trials has increased over time . Methods We identified all large NHLBI supported RCTs between 1970 and 2012 evaluating drugs or dietary supplements for the treatment or prevention of cardiovascular disease . Trials were included if direct costs > $ 500,000/year , participants were adult humans , and the primary outcome was cardiovascular risk , disease or death .  The 55 trials meeting these criteria were coded for whether they were published prior to or after the year 2000 , whether they registered in clinical trials.gov prior to publication , used active or placebo comparator , and whether or not the trial had industry co-sponsorship . We tabulated whether the study reported a positive , negative , or null result on the primary outcome variable and for total mortality . Results 17 of 30 studies ( 57 % ) published prior to 2000 showed a significant benefit of intervention on the primary outcome in comparison to only 2 among the 25 ( 8 % ) trials published after 2000 ( χ2=12.2,df= 1 , p=0.0005 ) . There has been no change in the proportion of trials that compared treatment to placebo versus active comparator . Industry co-sponsorship was unrelated to the probability of reporting a significant benefit . Pre- registration in clinical trials.gov was strongly associated with the trend toward null findings . Conclusions The number NHLBI trials reporting positive results declined after the year 2000 . Prospect i ve declaration of outcomes in RCTs , and the adoption of transparent reporting st and ards , as required by clinical trials.gov , may have contributed to the trend toward null findings Aim : To test a theory of visual stress by investigating the inter-relationships between ( 1 ) the threshold contrast/saturation at which individuals first report discomfort when viewing colored gratings of progressively increasing contrast and decreasing saturation ; ( 2 ) the choice of a colored overlay for reading ; ( 3 ) any increase in reading speed when the overlay is used . Method : Ninety-five young adults , with normal color vision , reported illusions from square-wave gratings ( Pattern Glare Test ) , chose any colored overlays that improved clarity ( Intuitive Color Overlays ) and read aloud r and omly ordered common words ( Wilkins Rate of Reading Test ) . This was followed by an automated choice of tints for text using various screen colors on a tablet , and a test of discomfort from patterns of progressively increasing contrast and decreasing saturation , using software developed for this study . All participants wore their optimal refractive correction throughout the procedure . Results : Fifty-eight participants chose a colored overlay and reported that it made text easier and more comfortable to read . On average , these individuals had a greater improvement in reading speed with their overlays ( p = 0.003 ) , a lower contrast threshold at which discomfort from achromatic gratings was first reported ( p = 0.015 ) , and a tendency to report more pattern glare ( p = 0.052 ) , compared to the other participants . Participants who chose both a most and least preferred tint for text using the automated procedure reported discomfort from colored gratings at a significantly higher contrast with their most preferred color compared to their least preferred color ( p = 0.003 ) . The choice of a colored tint was moderately consistent across tests . The most and least preferred colors tended to be complementary . Conclusion : Colored tints that improved reading speed reduced pattern glare both in terms of the illusion susceptibility and in terms of discomfort contrast threshold , supporting a theory of visual stress . An automated test that incorporates colored gratings and a choice of most and least preferred color might better identify individuals whose reading speed improves with colored overlays Flaws in the design , conduct , analysis , and reporting of r and omised trials can cause the effect of an intervention to be underestimated or overestimated . The Cochrane Collaboration ’s tool for assessing risk of bias aims to make the process clearer and more 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 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 Background The ' Hawthorne Effect ' may be an important factor affecting the generalisability of clinical research to routine practice , but has been little studied . Hawthorne Effects have been reported in previous clinical trials in dementia but to our knowledge , no attempt has been made to quantify them . Our aim was to compare minimal follow-up to intensive follow-up in participants in a placebo controlled trial of Ginkgo biloba for treating mild-moderate dementia . Methods Participants in a dementia trial were r and omised to intensive follow-up ( with comprehensive assessment visits at baseline and two , four and six months post r and omisation ) or minimal follow-up ( with an abbreviated assessment at baseline and a full assessment at six months ) . Our primary outcomes were cognitive functioning ( ADAS-Cog ) and participant and carer-rated quality of life ( QOL-AD ) . Results We recruited 176 participants , mainly through general practice s. The main analysis was based on Intention to treat ( ITT ) , with available data . In the ANCOVA model with baseline score as a co-variate , follow-up group had a significant effect on outcome at six months on the ADAS-Cog score ( n = 140 ; mean difference = -2.018 ; 95%CI -3.914 , -0.121 ; p = 0.037 favouring the intensive follow-up group ) , and on participant-rated quality of life score ( n = 142 ; mean difference = -1.382 ; 95%CI -2.642 , -0.122 ; p = 0.032 favouring minimal follow-up group ) . There was no significant difference on carer quality of life . Conclusion We found that more intensive follow-up of individuals in a placebo-controlled clinical trial of Ginkgo biloba for treating mild-moderate dementia result ed in a better outcome than minimal follow-up , as measured by their cognitive functioning . Trial registration Current controlled trials : IS RCT 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 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 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 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 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 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 ) 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 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 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 This study investigated the long-term effects of using coloured filters on the frequency and type of errors in oral reading . A double-masked , placebo-controlled crossover experimental design was used , with subjects being assessed over a period of 20 months . There were three experimental groups ( Placebo tints , Blue tints , and Diagnosed tints ) involving 113 subjects with reading difficulties , ranging in age from 9.2 yr to 13.1 yr . The 35 controls ( ranging in age from 9.4 yr . to 12.9 yr . ) had reading difficulties but did not require coloured filters . There was a significant improvement for all groups in the accuracy of miscues over the period , although experimental groups over-all did not improve at a significantly different rate than the control group . The failure to find significantly greater improvement for the experimental groups over the control group for the total period , despite subjects ' reports of improved print clarity , may be partly related to the lack of effective letter-sound analysis and synthesis skills and to the use of a word- identification strategy of guessing based on partial visual analysis This study investigated the effects of using coloured filters on reading speed , accuracy , and comprehension as well as on perception of academic ability . A double-masked , placebo-controlled crossover design was used , with subjects being assessed over a period of 20 mo . There were three treatment groups ( Placebo filters , Blue filters , and Optimal filters ) involving 113 subjects with “ reading difficulties ” , ranging in age from 9.2 yr . to 13.1 yr . and with an average discrepancy between chronological age and reading age of 1.8 yr . The 35 controls ( who did not use coloured filters ) ranged in age from 9.4 yr . to 12 9 yr . , with an average discrepancy between chronological age and reading age of 21 yr The treatment groups increased at a significantly greater rate than the control group in reading accuracy and reading comprehension but not for speed of reading . For self-reported perception of academic ability , two of the three treatment groups showed significantly greater increases than the control group . The larger improvements for treatment groups in reading comprehension may be related to a reduction in print and background distortions allowing attention to be directed to the processing of continuous text rather than to the identification of individual words . A reduction in print distortion , however , may not be sufficient to generate improved word- identification skills without additional remedial support , and this may be indicated by the nonsignificant increase in rate of reading 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 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 This study tested the predictions derived from two explanatory theoretical models of the effects of colored filters on reading speed : the theory of attributional bias and the theory of visual stress associated with reading . The experimental group consisted of 27 secondary school students ( 14 boys , 13 girls ) diagnosed with the Meares-Irlen syndrome ; the control group had 27 students paired in age and sex with the experimental group . The mean age of the sample was 12 years , 10 months ( SD = 8.9 mo . ) . The effects of colored filters on reading speed and accuracy were tested using a  word reading test and a visual stress induction text . The presentation method tapped individuals ' visual sensitivity and response criteria . The results support some predictions of the theory of attributional bias , but more research is needed to assess each theory of reading speed Visual stress-a condition in which unpleasant visual symptoms are experienced when reading-has been reported to be more prevalent in dyslexic individuals but at the present time the relationship between dyslexia and visual stress remains controversial . ViSS , a computerized visual stress screener that incorporates reading-like visual search , has recently shown promise in studies with unselected sample s of primary and secondary school children . This study investigated the use of ViSS with dyslexic children . Dyslexic children identified as having high visual stress showed significantly higher per cent increases in reading rate with a coloured overlay and reported significantly higher critical symptoms of visual stress , compared to dyslexic children with low visual stress . The same results were found for reading-age controls , indicating that ViSS can be equally effective with normal readers as well as with children with dyslexia . Compared to reading-age controls , dyslexic children were found to have significantly higher susceptibility to visual stress , significantly larger per cent increases in reading rate with an overlay , and significantly higher critical and non-critical symptoms of visual stress . Extrapolated to unselected population sample s , the data also suggest that visual stress is more likely to be found in people with dyslexia than in people who do not have dyslexia . These results , which point to an important link between the two conditions , are discussed in relation to current theories that attribute visual stress to either a magnocellular dysfunction or cortical hyperexcitability The efficacy and side effects of the synthetic cannabinoid nabilone were compared with those of the weak opioid dihydrocodeine in the treatment of chronic neuropathic pain . A r and omised , double blind , crossover trial study design was used . Participants received a maximum daily dose of 2 mg nabilone or 240 mg dihydrocodeine . The trial lasted for 14 weeks and comprised two treatment periods , each of six weeks ’ duration , separated by a two week washout period . Participants were patients with chronic neuropathic pain aged 23 - 84 years , who were recruited using convenience sampling from outpatient units at three hospitals in the United Kingdom . The sample comprised 96 patients , who were r and omised to nabilone ( n=48 ) and dihydrocodeine ( n=48 ) in the first treatment period.1 The main outcome was pain as measured on a visual analogue scale over the final two weeks of each treatment period . Side effects were measured by a question naire . The research ers reported that dihydrocodeine provided better pain relief than nabilone and had slightly fewer side effects , although no major adverse events occurred for either drug . Which of the following statements , if any , are true ? Statements a , b , c , d , and e are all true . The aim of the trial was to compare the efficacy and side effects of nabilone with dihydrocodeine in the treatment of chronic neuropathic pain . A r and omised double blind crossover trial was conducted . Participants received both treatments in succession , 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 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
target: 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
background: 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 .