Irlen filters

Irlen Filters or Irlen Lenses, are coloured overlay filters or tinted lenses that are intended to help people with learning disabilities to improve their ability to read. Standardised diagnostic procedures have been developed to individualise the colour selection. The treatment is based on the idea of the scotopic sensitivity syndrome. According to critics, both the syndrome and the treatment are controversial and based on insufficient research. [cite journal| last = International Dyslexia Association| title = Controversial therapies | journal = IDA Information Packet| pages = 1–20| date = 2004| url =] There is evidence of the efficacy of the method, but the research findings have been ambiguous.

cotopic Sensitivity Syndrome

Scotopic sensitivity syndrome, also known as the Irlen Syndrome or Meares-Irlen syndrome or sensitivity, is said to be a visual defect related to difficulties with light source, glare, luminance, wave length and black/white contrast. According to Irlen, these difficulties lead to reading problems that can be alleviated by the use of tinted lenses.

The syndrome has six characteristics:

#eye strain
#poor visual resolution
#a reduced span of focus
#impaired depth perception
#poor sustained focus

The scotopic sensitivity syndrome is diagnosed by interviewing the client and by observing responses to certain visual tasks such as interpreting geometric figures and reading. 50 percent of clients are diagnosed as suffering from the syndrome, and these are asked to read a text through a series of tinted overlays. The client is asked which of the overlays is the most comfortable. The results of this screening examinations are then interpreted at an Irlen Center and the final tint is selected. [cite journal| last = Helveston | first = Eugene M.| title = Tinted Lenses
journal = IDA Information Packet| pages = 12–13| date = 2004| url =

History and research

Tinted lenses were initially proposed in 1980 by Olive Meares [Meares, O. (1980). Figure/ground, brightness contrast and reading disabilities. Visible Lang. 14, 13-29] , to improve the reading ability of people with a learning disability, specifically a certain type of dyslexia. Later this was taken further by psychologist Helen Irlen. The proposition by Irlen was made at the Annual Meeting of the American Psychological Association in 1983. At that time, there was little research made on the effect of tinted lenses. Irlen gained notable publicity demonstrating the efficacy of her method on television. Tinted lenses became a commercial success, and testing and prescribing centers were opened throughout USA. [cite journal| last = Silver | first = Larry B.| title = Theme editor's note
journal = IDA Information Packet| pages = 12| date = 2004| url =

There has been research on the efficacy of using Irlen filters and lenses since the 1990s. The research findings have been ambiguous: many studies indicated increased comfort and performance in reading of some of the subjects diagnosed as having the Irlen syndrome. The data support the hypothesis that undiagnosed vision problems may be the primary underlying factor common to individuals who report a benefit from the intervention, but not necessarily that scotopic sensitivity is a distinct entity. []

More lately, there has been accumulating evidence indicating that vision problems, such as pattern sensitivity, can be reduced or eliminated using coloured overlays and tints, and products with a solid research basis have appeared in the market. Dyslexic readers have shown up to a 25% advantage in reading speed with a coloured overlay of their choice. Additionally, coloured overlays and tints have been shown to reduce the symptoms of migraine which is not related to dyslexia. However, the aetiology of the Meares–Irlen syndrome remains under-specified. Instead of the Irlen diagnose, the assessment of pattern glare and perceptual distortion seems to be the most meaningful method of determining whether the use of a coloured overlay is beneficial for those who experience glare and discomfort when reading. [cite journal| last = Hollis & Allen | title = Screening for Meares-Irlen sensitivity in adults: can assessment methods predict changes in reading speed? | journal = Ophthalmic & physiological optics | volume = 26| issue = 6 | pages = 566–71 | date = 2006| url = | doi = 10.1111/j.1475-1313.2006.00401.x]

Other purposes

According to Irlen, the lenses can be used to treat a wide variety of problems that are associated with light sensitivity, discomfort and distortions. According to proponents, tinted lenses have helped people with a head injury, concussion, whiplash, perceptual problems, neurologic impairment, memory loss, language deficits, headaches and migraine, autoimmune disease, fibromyalgia, macular degeneration, cataracts, retinitis pigmentosa, complications from an eye operation, depression, chronic anxiety and others. It has also been claimed that a treatment for scotopic sensitivity syndrome could help a number of incarcerated individuals and delinquent children. [cite journal| last = Helveston | first = Eugene M.| title = Tinted Lenses
journal = IDA Information Packet| pages = 12–13| date = 2004| url =


The Irlen method has been criticised of being put to the market prior to serious research. According to Helveston, the scotopic sensitivity syndrome and its treatment has, as a phenomenon, resulted in classic group behaviour and has the characteristics of a fad with a charismatic personality as a leader and the supporting evidence being mostly anecdotal. The syndrome is however, associated with a growing array of possibly diverse conditions, as well as world-wide franchise according to critics. [cite journal| last = Helveston | first = Eugene M.| title = Tinted Lenses
journal = IDA Information Packet| pages = 12–13| date = 2004| url =

Research does however point quite consistently to a genuine underlying problem relating most likely to the central nervous system of those diagnosed with the syndrome. Even critics such as Helveston do not dispute this (rather their concern seems based on the way the condition has been "claimed" and "marketed" as opposed to its existence). It appears the severity of the Syndrome can diverge quite widely though. Fact|date=April 2008

External links

* [ Irlen Institute: FAQ]
* [ Irlen patent summary]
* [ LDRC: Irlen filters and learning disabilities] "(review article)"
* [ ACNT: Irlen colored filters] "(review article)"
* [ Irlen Filter - Freeware software color filter]

ee also

Alternative therapy (disability)


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