Coloured filters are designed to help individuals who suffer from a condition known as visual stress. People with this condition are especially sensitive to lights, glare, patterns, colours, and contrast.
Coloured filters are designed to block the specific wavelengths of light to which an individual is sensitive. So, for example, an individual might be especially sensitive to blue light and therefore use a blue filter to reduce its effects.
There are several types of coloured filters including overlays and lenses. Coloured overlays are clear plastic sheets that can be placed on top of reading materials, such as books or newspapers. Coloured lenses are tinted, non-optical lenses which can be put into spectacle frames.
Some people believe that coloured filters can be used to help autistic people who suffer from visual stress, leading to improvement in their visuospatial abilities. This may in turn lead to improvements in other areas, such as reading ability.
There is no research evidence to suggest that coloured lenses provide any kind of benefit for autistic people.
There is some very limited, low quality research evidence to suggest that coloured overlays could be useful for some autistic children and young people with a range of problems including difficulties with reading and recognition of emotions in other people.
Small-scale, pilot trials of the effects of coloured filters could be carried out on autistic individuals to determine their effectiveness and safety.
If you have any concerns about your eyesight, or the eyesight of someone else that you care for, you should consult an optometrist in case there are any vision problems that have not been recognised.
Please read our Disclaimer on Autism Interventions
Coloured filters are designed to help individuals with visual processing difficulties, visual stress and related problems.
People with visual processing difficulties are especially sensitive to lights, glare, patterns, colours, and contrast. People with visual stress may experience perceptual distortions and discomfort, especially when reading printed text.
Some people have suggested that visual processing difficulties and/or visual stress are common in people with conditions such as reading and learning difficulties, ADHD or autism. For example, the Irlen website, accessed on 2 March 2016, claims that Irlen syndrome [visual stress] affects 33% of autistic people, although we have found no evidence to support this claim.
According to Ludlow et al (2007),
“The visual processing abnormalities commonly reported in ASD include hyper sensitivity to lights and colors and experiences of visual distortion, which may, for example, alter the perceived dimensions of rooms. Visual distortions can also result in difficulties writing on printed lines and maintaining appropriate spacing between letters and words. Whilst there is no clear consensus about the root cause of these difficulties it has been suggested that some individuals with autism suffer from a co-occurring disorder called visual stress. Visual stress refers to perceptual distortions and discomfort, most notably when reading printed text. Williams has suggested that the co-occurrence of autism and visual stress results in particularly dramatic symptoms characterised by fragmentary perception. “
The aim of coloured filters is to block out the frequencies of light to which the individual is sensitive, allowing the brain to process visual information normally. For example, according to the Irlen website, accessed on 2 March 2016,
“Seventy percent of the information an individual receives enters through the eyes and must be correctly interpreted by the brain. Any problem in the way the brain processes visual information can cause difficulties in the general ability to function. Sensory overload causes problems processing, interpreting, and interacting with the environment. The Irlen Method helps individuals with Autism and Asperger Syndrome who have perceptual problems, light sensitivity, and sensory overload by filtering the frequencies of light to which the individual is sensitive. This allows the brain to process visual information normally.”
It is important to note that visual processing difficulties and visual stress are different to other problems with vision, such as long-sight or short sight. Of course, the same person may suffer from more than one type of vision problem at the same time.
There have been a number of studies which claim that coloured overlays can help some autistic individuals. For example,
Ludlow et al (2006) reported “Findings showed that 15 out of 19 (79%) children with autism showed an improvement of at least 5% in reading speed when using a coloured overlay. In contrast only 3 of 19 (16%) control group children showed such an improvement. The findings suggest that coloured overlays may provide a useful support for reading for children with autism.
Ludlow et al (2012) reported “The current findings are important in showing that perceptual abnormalities in a large proportion of children with autism benefit from the use of an overlay, not just in respect of reading ability, but also as regards improvements in perception of facial expression. This then provides further evidence that lowlevel perceptual abnormalities may be responsible for their difficulties attending and processing facial expressions.”
Whitaker et al (epub) reported “Judgments of emotional intensity improved significantly with the addition of the preferred colored tint in the ASD group but not in controls, a result consistent with a link between visual stress and impairments in processing facial expressions in individuals with ASD.”
We have been unable to identify any studies which make claims for the use of coloured lenses. However, the Irlen Institute website, accessed on 3 March 2016, makes the following claims.
“The Irlen Method is not a cure for Autism or Asperger Syndrome. Not every individual with Autism and Asperger Syndrome suffers with perceptual problems, light sensitivity, and sensory overload. The Irlen Method is a piece of the puzzle for some individuals. Typical problems that can be helped by the Irlen Method are ..." sensory overload, environmental distortions and print distortions.
Coloured filters are tools, such as coloured lenses or coloured overlays, which block specific light frequencies. Coloured lenses are tinted, non-optical lenses which can be put into spectacle frames. Coloured overlays are clear plastic sheets that can be placed on top of reading materials, such as books or newspapers.
Coloured filters are designed to block the specific wavelengths of light to which an individual is sensitive. So, for example, an individual might be especially sensitive to blue or yellow light and therefore use an appropriate filter to reduce its effects.
Coloured filters are used to help individuals with visual processing difficulties and/or visual stress. People with visual processing difficulties are especially sensitive to lights, glare, patterns, colours, and contrast. People with visual stress may experience perceptual distortions and discomfort, especially when reading printed text.
According to Lewis et al (Date unknown)
“The reader should place the [overlay] sheet over the page, when reading. The text should be positioned to avoid reflections from the surface of the overlay caused by lighting. The overlay should not be creased, and it is a good idea to keep it in an envelope when it is not in use.
”Children who persist in using their overlay usually find coloured glasses more convenient to use. Glasses can help with writing, whereas overlays cannot. The degree of precision in the choice of colour is critical for obtaining the best results, and the precision available with lenses is far greater than with overlays. Perhaps for this reason glasses often give better results.
“It is essential to realise that the appropriate colour for use in glasses is not the same as that in overlays. For example, a child may choose a yellow overlay and benefit from blue lenses. The colour of the lenses can only be assessed by optometrists or orthoptists who use the Intuitive Colorimeter, or by the use of a very large number of coloured trial lenses. Other methods of selecting coloured lenses may be less likely to select the optimal colour.”
Some optometrists will undertake a coloured lens test to determine if coloured overlays are likely to be of benefit. Different optometrists will charge different rates for the test, depending on where they are based and the precise nature of the testing they carry out. We have seen coloured lens tests advertised at various prices between £20 and £100 in the UK and $295-$595 in the USA.
Optometrists will charge different rates for the spectacles and lenses that they prescribe depending on where they are based and the precise formulation of the glasses and lenses. Typically prices are likely to start at £100 plus in the UK but can be much, much more.
Some optometrists will also undertake a coloured overlay test to determine if coloured overlays are likely to be of benefit. Some of them will do this at the same time that they carry out a coloured lens test. They will charge different rates, depending on where they are based and the precise nature of the testing they carry out. We have seen tests advertised at various prices between £20 and £100 in the UK. We have not identified any prices in the USA or other countries for coloured overlay tests.
Coloured overlays are available as single sheets or in multiple packs of 5, 10 etc. from a range of optometrists and other commercial suppliers. We have seen single sheets and multiple packs for sale at various prices between £3.50 and £10.00 in the UK. We have not identified any prices in the USA or other countries for coloured overlay sheets.
Some optometrists will undertake a coloured lens test to determine if coloured lenses are likely to be of benefit. The coloured lens test usually takes around 15-60 minutes depending on the provider and the nature of the test.
According to the Irlen Institute website, accessed on 3 March 2016,
“Individuals usually wear their Irlen Spectral Filters for the rest of their lives. The problems return whenever the glasses are removed. We re-evaluate each person once a year to determine whether the color is still working or needs to be changed. Colors change over time. When they change, the benefits from wearing color diminish.”
Some optometrists will undertake a coloured overlay test to determine if coloured overlays are likely to be of benefit. The coloured overlay test usually takes around 15-60 minutes depending on the provider and the nature of the test.
According to Lewis et al (Date unknown)
“It seems that children benefit most from colour if it is offered as soon as any reading difficulty is suspected, before the cycle of failure has begun. Many 7-year-olds appear to use coloured overlays for a year or two and then discard them as unnecessary. This may be because the acquired familiarity with text then makes the distortions less distracting.”
The Irlen Institute advises that choosing the right colour is critical. It states that using lenses with the wrong colour can even make things worse, causing more stress and increased perceptual difficulties.
“Each individual needs his/her own color and wears that color all the time, both inside and outside. If individuals are sensitive to light and color, the wrong color can create strain, fatigue, headaches, make them sick or dizzy, or create a more distorted environment. Once the offending colors of the light spectrum are determined, positive changes happen.”
According to the Eyecare Trust website, accessed on 4 March 2016,
“Just as some colours are reported as being beneficial, others are often reported to be uncomfortable. Individuals sometimes show a marked aversion to these uncomfortable colours. Provided the appropriate colour is chosen, it seems unlikely that overlays can have any detrimental effect. The possible long-term effects of wearing coloured glasses are unknown at present.”
The Irlen Institute states that only children who can tolerate wearing glasses or goggles should be tested.
Lewis et al (Date unknown) reported that
“In our opinion, overlays can be used regardless of any simultaneous eye exercises or medical treatment. However, since visual perceptual distortions can sometimes be caused solely by binocular vision problems, it is often sensible to have these corrected first. If the distortions remain then coloured filters need to be tried.”
There are a number of coloured lens providers in the UK, the USA and other countries.
In the UK, optometrists can be found in most town centres. Optometrists examine eyes to assess their health and to determine whether glasses or eye exercises are needed. A small but growing number of optometrists have specialised in assessing people who have reading difficulties. You can obtain a list of optometrists who prescribe coloured lenses from the Society for Coloured Lens Prescribers or the College of Optometrists.
Some optometrists can also provide coloured overlays. In addition, there are a number of commercial suppliers which will sell coloured overlays.
Please note: According to the Eye Care Trust website, accessed on 3 March 2016, “It is not sufficient to try the coloured sheets available from stationers because the colours are not subtle or varied enough.”
In the UK, optometrists must be registered with the General Optical Council.
The only people able to prescribe and supply Irlen lenses are staff of the Irlen Institute or affiliated clinics. There are many Irlen-affiliated clinics worldwide with staff who are able to test and prescribe Irlen coloured filters.
We have been unable to identify any formal qualifications required to prescribe coloured overlays. However, we strongly recommend you should consult a qualified optometrist who will be able to identify any other vision problems.
Helen Irlen, a psychologist, discovered that colour can affect the way the brain processes visual information. She believed that, in some individuals, the nervous system is wired differently and reacts badly to some colours. This causes problems processing, interpreting, and interacting with the environment.
In 1983 she invented Irlen lenses and overlays, which are designed to filter out the colours which cause the problems. Sometime later Professor Arnold Wilkins at the University of Essex developed a set of coloured filters which he called ‘Intuitive Overlays.’ These are designed to do the same thing.
We have identified eight scientific studies of the use of Irlen lenses for people with reading difficulties published in peer-reviewed journals. However, because it is unclear if these studies included autistic people, we have not included them in our evaluation.
We have identified five scientific studies of coloured overlays for autistic people published in peer-reviewed journals.
We have identified one scientific study which looked at coloured glasses and at coloured overlays.
The studies with autistic participants included a total of more than 140 individuals aged from 7 to 26 years old.
There are a number of limitations to all of the research studies published to date. For example
For a comprehensive list of potential flaws in research studies, please see "Why some autism research studies are flawed."
We have been unable to identify any studies into coloured filters that are currently underway. If you know of any other studies we should include please email info@researchautism.net with the details. Thank you.
There is no research evidence to suggest that coloured lenses are useful for autistic people with visual processing difficulties or visual stress.
There is some very limited, low quality research evidence to suggest that coloured overlays could be useful for some autistic children and young people with a range of problems including difficulties with reading and recognition of emotions in other people.
This lack of evidence does not prove or disprove the effectiveness of coloured lenses for autistic people. It simply shows how little research has been conducted to date.
Small-scale, pilot trials of the effects of coloured filters could be carried out on autistic individuals to determine their effectiveness and safety.
This section provides details of scientific studies into the effectiveness of this intervention for autistic people which have been published in English-language, peer-reviewed journals.
If you know of any other publications we should list on this page please email info@informationautism.org
Please note that we are unable to supply publications unless we are listed as the publisher. However, if you are a UK resident you may be able to obtain them from your local public library, your college library or direct from the publisher.
This section provides details of other publications on this topic.
You can find more publications on this topic in our publications database.
If you know of any other publications we should list on this page please email info@informationautism.org
Please note that we are unable to supply publications unless we are listed as the publisher. However, if you are a UK resident you may be able to obtain them from your local public library, your college library or direct from the publisher.
This section provides details of personal accounts of the use of coloured filters for autistic people.
Personal accounts can be useful sources of information about the intervention but are not as scientifically valid or reliable as research trials. This may be especially true where the accounts are published by an organisation which might gain a financial advantage from the take-up of the intervention.
Please note that the views expressed in these personal accounts do not necessarily represent our views.
We have been unable to identify any personal anecdotes about the use of coloured overlays in people on the autism spectrum.
The Irlen website(Open in New Window) provides some personal accounts of the use of coloured lenses
If you know of any other personal accounts we should include please email info@researchautism.net with the details.
If you have any concerns about your eyesight, or the eyesight of someone else that you care for, you should consult an optometrist in case there are any vision problems that have not been recognised.
According to Lewis et al (Date unknown),
“The term Visual Stress is sometimes used to refer to the collection of symptoms and signs of visual fatigue when reading that are reduced when colour is used as therapy. Other terms are Meares-Irlen syndrome, Irlen syndrome or Scotopic Sensitivity Syndrome (SSS). (The syndrome is not yet widely recognised by the medical and scientific communities, and there is no universal agreement on its name.)”