Do tinted lenses improve the reading performance of dyslexic children? A cohort study

The Use of Chromagen Lenses in Different Ocular and Non-ocular Conditions: A Prospective Cohort Study

Background

In this study, we aimed to evaluate the efficacy of chromagen lenses and compare the pre- and post-intervention outcomes among individuals with non-ocular conditions such as dyslexia and Irlen syndrome and ocular conditions such as color vision deficiency (CVD) and cone-rod dystrophy (CRD).

Methodology

This prospective cohort study was conducted from 2016 to 2021 among cases (seven years or older) who were diagnosed with dyslexia, Irlen syndrome, CVD, or CRD. Participants were given a short questionnaire to read, followed by asking direct questions regarding medical health history, ocular history, eyeglasses prescription, and a full orthoptics evaluation. The main outcomes were the improvement in reading speed, reading accuracy, and visual stress.

Results

A total of 156 patients were included in this study; 110 patients with dyslexia, 19 with Irlen syndrome, 16 with CVD, and 11 with CRD. The findings showed that the reading speed and accuracy were improved in 96.34% of patients with dyslexia and 78.9% of patients with Irlen syndrome. The use of a chromagen lens was significantly associated with visual stress improvement in 89.8% of patients (p = 0.02). Photosensitivity was significantly improved after wearing the chromagen lenses in patients with CVD (87.5%) and CRD (63.6%).

Conclusions

The study findings showed a positive impact of chromagen lenses on reducing visual stress, including reading speed and accuracy, in patients with dyslexia and Irlen syndrome. Photosensitivity improved in patients with Irlen syndrome and CRD. Color vision was enhanced in patients with CVD. However, further studies are required to investigate the predictors of improvement and assess the long-term efficacy of chromagen lenses on daily activities and learning skills.

Irlen syndrome: systematic review and level of evidence analysis

BACKGROUND

Scotopic sensitivity syndrome, later called Meares-Irlen syndrome or simply Irlen syndrome (IS) has been described as symptoms of poor reading ability due to poor color matching and distorted graphic images. Individuals with this syndrome are considered slow, ineffective readers with low comprehension and visual fatigue. It is still uncertain whether the disease pathophysiology is an independent entity or part of the dyslexia spectrum. Nevertheless, treatments with lenses and colored filters have been proposed to alleviate the effect of the luminous contrast and improve patients' reading performance. However, no evidence of treatment effectiveness has been achieved.

OBJECTIVE

The aim of the present study was to obtain evidence about IS etiology, diagnosis and intervention efficacy.

METHODS

A systematic review was performed covering the available studies on IS, assessing the available data according to their level of evidence, focusing on diagnostic tools, proposed interventions and related outcomes.

RESULTS

The data showed high heterogeneity among studies, and lack of evidence on the existence of IS and treatment effectiveness.

CONCLUSION

The syndrome as described, as well as its treatments, require further strong evidence.

The effect of coloured overlays and lenses on reading: a systematic review of the literature

PURPOSE

There are many anecdotal claims 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.

METHODS

We systematically reviewed the literature concerning the effect of coloured lenses or overlays on reading performance by searching the PsychInfo, Medline and Embase databases. This revealed 51 published items (containing 54 data sets). Given that different systems are in use for issuing coloured overlays or lenses, we reviewed the evidence under four separate system headings (Intuitive, Irlen, Harris/Chromagen and Other), classifying each published item using the Cochrane Risk of Bias tool.

RESULTS

Although the different colour systems have been subjected to different amounts of scientific scrutiny, the results do not differ according to the system type, or whether the sample under investigation was classified as having visual stress (or a similarly defined condition), reading difficulty, or both. The majority of studies are subject to 'high' or 'uncertain' risk of bias in one or more key aspects of study design or outcome, with studies at lower risk from bias providing less support for the benefit of coloured lenses/overlays on reading ability. 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. We discuss the strengths and shortcomings of the published literature and, whilst acknowledging the difficulties associated with conducting trials of this type, offer some suggestions about how future trials might be conducted.

CONCLUSIONS

Consistent with previous reviews and advice from several professional bodies, we conclude that the use of coloured lenses or overlays to ameliorate reading difficulties cannot be endorsed and that any benefits reported by individuals in clinical settings are likely to be the result of placebo, practice or Hawthorne effects.

A systematic review of controlled trials on visual stress using Intuitive Overlays or the Intuitive Colorimeter

Claims that coloured filters aid reading date back 200 years and remain controversial. Some claims, for example, that more than 10% of the general population and 50% of people with dyslexia would benefit from coloured filters lack sound evidence and face validity. Publications with such claims typically cite research using methods that have not been described in the scientific literature and lack a sound aetiological framework. Notwithstanding these criticisms, some researchers have used more rigorous selection criteria and methods of prescribing coloured filters that were developed at a UK Medical Research Council unit and which have been fully described in the scientific literature. We review this research and disconfirm many of the more extreme claims surrounding this topic. This literature indicates that a minority subset of dyslexics (circa 20%) may have a condition described as visual stress which most likely results from a hyperexcitability of the visual cortex. Visual stress is characterised by symptoms of visual perceptual distortions, headaches, and eyestrain when viewing repetitive patterns, including lines of text. This review indicates that visual stress is distinct from, although sometimes co-occurs with, dyslexia. Individually prescribed coloured filters have been shown to improve reading performance in people with visual stress, but are unlikely to influence the phonological and memory deficits associated with dyslexia and therefore are not a treatment for dyslexia. This review concludes that larger and rigorous randomised controlled trials of interventions for visual stress are required. Improvements in the diagnosis of the condition are also a priority.

Attentional Gating in Primary Visual Cortex: A Physiological Basis for Dyslexia

The visual magnocellular pathway is known to play a central part in visuospatial attention and in directing attention to specific parts of the visual world in serial search. It is proposed that, in the case of reading, this mechanism is trained to perform a sequential gating of visual information coming into the primary visual cortex to enable further orderly processing by the ventral stream. This scheme, taken together with the potential for plasticity between the different afferent channels in the case of a relative impairment of the magnocellular system, can provide some limited rationale for the beneficial effects that have been claimed for the use of coloured overlays and glasses.

Supporting Children with Visual Stress: The Development of a Web Resource for Parents and Professionals

Introduction

Visual stress is a condition which makes reading difficult. The use of coloured lenses in spectacles to alleviate the symptoms of visual stress has attracted increasing interest. The aim was to develop a web-based resource to centralize information about the condition and the processes for the screening, assessment, and provision of coloured lenses.

Method

Action research methods were employed. The exploratory phase used semi-structured interviews to gather parents' and professionals' views on the condition and their suggestions for the content and layout of a supporting web resource. The innovatory phase was used to design the prototype web resource. The evaluative phase was used to appraise and enhance the prototype website and collate data on website usage.

Results

Parents and professionals had some awareness of the condition but felt less sure of the evidence base for coloured lenses. Professionals valued research as evidence, whereas parents preferred testimonials. Suggestions for the content of a web resource to centralize information on the topic were clearly articulated by professionals, parents, and experts in the field. In the first year, over 7,500 individual web users visited the resource.

Conclusion

The first collaborative resource on the topic has been successfully produced, thereby offering a centralized information resource.

A comparison of two-coloured filter systems for treating visual reading difficulties

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 randomised, 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.

Effects of wearing yellow spectacles on visual skills, reading speed, and visual symptoms in children with reading difficulties

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 prospective study was performed in 82 non-dyslexic children with reading difficulties in grades 3-6 (aged 9-11 years) from 11 elementary schools in Madrid (Spain). The children were randomly 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) questionnaire 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 clinically insignificant.

Irlen colored overlays do not alleviate reading difficulties

OBJECTIVES

To test the efficacy of Irlen colored overlays for alleviating reading difficulties ostensibly caused by Irlen syndrome, a proposed perceptual disorder with controversial diagnostic status.

PARTICIPANTS AND METHODS

Sixty-one schoolchildren (aged 7-12 years) with reading difficulties were assessed by an Irlen diagnostician. We used a within-subject study design to examine differences in reading rate across 3 conditions: using an overlay of a prescribed color; using an overlay of a nonprescribed color; and using no overlay. In a subset of 44 children, all of whom had a diagnosis of Irlen syndrome, we also used a between-group design to test the effects of Irlen colored overlays on a global reading measure.

RESULTS

The Irlen diagnostician diagnosed Irlen syndrome in 77% of our poor readers. We found no evidence for any immediate benefit of Irlen colored overlays as measured by the reading-rate test or the global reading measure.

CONCLUSIONS

Our data suggest that Irlen colored overlays do not have any demonstrable immediate effect on reading in children with reading difficulties.

Learning disabilities, dyslexia, and vision

Learning disabilities constitute a diverse group of disorders in which children who generally possess at least average intelligence have problems processing information or generating output. Their etiologies are multifactorial and reflect genetic influences and dysfunction of brain systems. Reading disability, or dyslexia, is the most common learning disability. It is a receptive language-based learning disability that is characterized by difficulties with decoding, fluent word recognition, rapid automatic naming, and/or reading-comprehension skills. These difficulties typically result from a deficit in the phonologic component of language that makes it difficult to use the alphabetic code to decode the written word. Early recognition and referral to qualified professionals for evidence-based evaluations and treatments are necessary to achieve the best possible outcome. Because dyslexia is a language-based disorder, treatment should be directed at this etiology. Remedial programs should include specific instruction in decoding, fluency training, vocabulary, and comprehension. Most programs include daily intensive individualized instruction that explicitly teaches phonemic awareness and the application of phonics. Vision problems can interfere with the process of reading, but children with dyslexia or related learning disabilities have the same visual function and ocular health as children without such conditions. Currently, there is inadequate scientific evidence to support the view that subtle eye or visual problems cause or increase the severity of learning disabilities. Because they are difficult for the public to understand and for educators to treat, learning disabilities have spawned a wide variety of scientifically unsupported vision-based diagnostic and treatment procedures. Scientific evidence does not support the claims that visual training, muscle exercises, ocular pursuit-and-tracking exercises, behavioral/perceptual vision therapy, "training" glasses, prisms, and colored lenses and filters are effective direct or indirect treatments for learning disabilities. There is no valid evidence that children who participate in vision therapy are more responsive to educational instruction than children who do not participate.

Dyslexia: a review of two theories

Optometrists will frequently see patients, who may have a diagnosis or a suspected diagnosis of dyslexia (specific reading disorder) and will need to manage and counsel such patients. There are many propounded theories on the cause(s) of dyslexia. Although most professionals in this area consider that dyslexia is chiefly a linguistic disorder, the possibility of a visual component is contentious. This article is a selective review of two commonly discussed theories that suggest a visual component in dyslexia; the magnocellular deficit theory and Meares-Irlen syndrome.

Personality dimensions of people who suffer from visual stress

Personality dimensions of participants who suffer from visual stress were compared with those of normal participants using the Eysenck Personality Inventory. Extraversion-Introversion scores showed no significant differences between the participants who suffered visual stress and those who were classified as normal. By contrast, significant differences were found between the normal participants and those with visual stress in respect of Neuroticism-Stability. These differences accord with Eysenck's personality theory which states that those who score highly on the neuroticism scale do so because they have a neurological system with a low threshold such that their neurological system is easily activated by external stimuli. The findings also relate directly to the theory of visual stress proposed by Wilkins which postulates that visual stress results from an excess of neural activity. The data may indicate that the excess activity is likely to be localised at particular neurological regions or neural processes.

Screening for Meares?Irlen sensitivity in adults: can assessment methods predict changes in reading speed?

Two methods of assessing candidates for coloured overlays were compared with the aim of determining which method had the most practical utility. A total of 58 adults were assessed as potential candidates for coloured overlays, using two methods; a questionnaire, which identified self-reported previous symptoms, and a measure of perceptual distortions immediately prior to testing. Participants were classified as normal, Meares-Irlen sensitive, and borderline sensitive. Reading speed was measured with and without coloured overlays, using the Wilkins Rate of Reading Test and the change in speed was calculated. Participants classified as normal did not show any significant benefit from reading with an overlay. In contrast, a significant reading advantage was found for the borderline and Meares-Irlen participants. Current symptom rating was found to be a significant predictor of the change in reading speed, however the previous symptom rating was not found to be a reliable predictor. These data indicate that the assessment of perceptual distortions immediately prior to measuring colour preference and reading speed is the most meaningful method of assessing pattern glare and determining the utility of coloured overlays.

Visual training: current status in ophthalmology

PURPOSE

To inform ophthalmologists of the current status of visual training.

DESIGN

Personal perspective.

METHOD

A perspective and analysis of current practices that include a review of the literature and personal experiences of the author.

RESULTS

Visual training of some sort has been used for centuries. In the first half of the twentieth century, in cooperation with ophthalmologists, orthoptists introduced a wide variety of training techniques that were designed primarily to improve binocular function. In the second half of the twentieth century, visual training activities were taken up by optometrists and paramedical personnel to treat conditions that ranged from uncomfortable vision to poor reading or academic performance. Other visual training has been aimed at the elimination of a wide variety of systemic symptoms and for the specific improvement of sight and even for the improvement of athletic performance. At present, ophthalmologists and orthoptists use visual training to a very limited degree. Most visual training is now done by optometrists and others who say it works. Based on an assessment of claims and a study of published data, the consensus of ophthalmologists regarding visual training is that, except for near point of convergence exercises, visual training lacks documented evidence of effectiveness.

CONCLUSION

Although visual training has been used for several centuries, it plays a minor and actually decreasing role in eye therapy used by the ophthalmologist. At the beginning of the twenty-first century, most visual training is carried out by non-ophthalmologists and is neither practiced nor endorsed in its broadest sense by ophthalmology.

Predicting the continued use of overlays in school children--a comparison of the Developmental Eye Movement test and the Rate of Reading test

Coloured overlays have been advocated to enhance reading speed and ability in children with reading difficulty or dyslexia. Assessing the efficacy of overlays has to date been largely subjective. Objective assessment is presently carried out with the Rate of Reading test (RRT), where an increase in reading speed of more than 5% is considered to indicate a positive prognosis for continued use of the overlay. The Developmental Eye Movement (DEM) test is used to assess horizontal scanning behaviour in a number naming task. In this study both tests were utilised to determine whether coloured overlays could enhance reading performance or scanning. This article shows that for some children rate of reading is not improved with coloured overlays although performance on the DEM test does improve. Improvements to the DEM scores occurred in 88% of children who continued to use overlays for more than 3 months. This compared with 60% sensitivity in the RRT. The possible reasons for this phenomenon and the clinical implications are discussed.

Reading disorders in children

Reading difficulties are a complex set of disorders. Current research indicates that these disorders are not caused by vision abnormalities. Treatment of these disorders requires a multidisciplinary approach involving educators, psychologists, and physicians. Parents, physicians, and school officials should understand that there are no quick cures for these children.

Tinted spectacles and visually sensitive migraine

A double-masked randomized controlled study with cross-over design compared the effectiveness of precision ophthalmic tints in the prevention of headache in migraine sufferers. Seventeen patients chose the colour of light that optimally reduced perceptual distortion of text and maximized clarity and comfort. They were later given glasses with spectral filters providing optimal colour under conventional white lighting ('optimal' tint) or glasses that provided a slightly different colour ('control' tint). The tints were supplied in random order, each for 6 weeks, separated by an interval of at least 2 weeks with no tints. Headache diaries showed that the frequency of headaches was marginally lower when the 'optimal' tint was worn, compared with the 'control'. The trial extends to adults with migraine, the results of a previous double-masked study demonstrating, in children with reading difficulty, beneficial effects of precision tints in reducing symptom frequency. In the present study, however, the effects are suggestive rather than conclusive.

The familial incidence of symptoms of scotopic sensitivity/Irlen syndrome: comparison of referred and mass-screened groups

The familial incidence of Scotopic Sensitivity/Irlen Syndrome was investigated in two samples. One sample involved parents and siblings of 126 children identified with symptoms who had been referred for screening. The other sample involved parents and siblings of 33 children who had been identified with symptoms through mass screening of all children in Grades 3 to 6 at two local schools. Two different samples were taken to investigate the possibility of parental referral bias. Familial incidence may be inflated in a referred sample because some parents may be aware of their own symptoms and actively seek assistance. For the sample of children referred for screening, there was an 81% chance of either one or both parents showing similar symptoms and a 76% chance of siblings being similarly affected. For the sample of children identified through school screening, there was an 85%, chance of either one or both parents showing similar symptoms and a 54% chance of siblings being similarly affected. The data confirm previous estimates of incidence and suggest that Scotopic Sensitivity/Irlen Syndrome may be a genetically-based deficit in visual processing.

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

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 2.1 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 familial incidence of symptoms of Scotopic Sensitivity/Irlen syndrome

The familial incidence of Scotopic Sensitivity/Irlen Syndrome was investigated using parents of 751 children identified with symptoms. Children were identified by methods independent of their parents' symptoms or lack of symptoms. For these children, there was an 84% chance of either one or both parents showing similar symptoms, with similar numbers of mothers identified with symptoms as fathers. The data suggest that Scotopic Sensitivity/Irlen Syndrome may be a genetically based deficit in visual processing, but the simplest genetic models do not appear to fit.