Irlen spectral filters or Irlen lenses are coloured overlay filters or tinted lenses crafted specifically for the wearer and worn as glasses or contact lenses. They are intended to help people with the supposed perceptual processing difficulty known as Irlen syndrome, also known as scotopic sensitivity syndrome or visual stress, in which sensitivity to specific wavelengths of light provokes difficulty and discomfort when performing visually intensive activities such as reading. The existence of Irlen syndrome is controversial, although there is a small body of research supporting the use of colour to alleviate the symptoms associated with Irlen syndrome.

Scotopic sensitivity syndrome

Scotopic sensitivity syndrome is said to be a visual-perceptual defect related to difficulties with light source,

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luminance Luminance is a photometric measure of the luminous intensity per unit area of light travelling in a given direction. It describes the amount of light that passes through, is emitted from, or is reflected from a particular area, and falls withi ...

, wavelength, and contrast. According to Irlen, these difficulties lead to reading problems, eye strain, headaches, migraines, and other physical difficulties that can be alleviated by the use of person specific tinted lenses, known as Irlen spectral filters, worn as glasses or contact lenses. The syndrome has six characteristics: # photophobia #

eye strain Eye strain, also known as asthenopia (from Greek ''a-sthen-opia'', grc, ἀσθενωπία, ), is a common eye condition that manifests through non-specific symptoms such as fatigue, pain in or around the eyes, blurred vision, headache, and ...

#poor visual resolution #a reduced span of focus #impaired

depth perception Depth perception is the ability to perceive distance to objects in the world using the visual system and visual perception. It is a major factor in perceiving the world in three dimensions. Depth perception happens primarily due to stereopsis an ...

#poor sustained focus Scotopic sensitivity syndrome is diagnosed by interviewing the client and by observing responses to certain visual tasks such as interpreting geometric figures and reading.

History and research

The idea of page based distortion was initially suggested in 1980 by Olive Meares, 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. Diagnosis of Irlen Syndrome and treatment with Irlen Spectral Filters has been reviewed by the USA Medical Board, and has been determined as not the practice of medicine; it has also been reviewed by various USA Boards of Optometry and has been found not to be the practice of

optometry Optometry is a specialized health care profession that involves examining the eyes and related structures for defects or abnormalities. Optometrists are health care professionals who typically provide comprehensive primary eye care. In the Uni ...

Binocular Binocular may refer to: Science and technology * Binocular vision, seeing with two eyes * Binoculars, a telescopic tool * Binocular microscope, binocular viewing of objects through a single objective lens Other uses * Binocular (horse), a thoroug ...

and accommodative anomalies may occur in conjunction with the syndrome, but are not considered to be the underlying physiological basis of the condition.

Commercial claims of utility

According to Irlen, the lenses can be used to treat a wide variety of problems that are associated with light sensitivity, discomfort and distortions, including head injury,

concussion A concussion, also known as a mild traumatic brain injury (mTBI), is a head injury that temporarily affects brain functioning. Symptoms may include loss of consciousness (LOC); memory loss; headaches; difficulty with thinking, concentration, ...

, whiplash, perceptual problems, neurologic impairment, memory loss, language deficits, headaches and

migraine Migraine (, ) is a common neurological disorder characterized by recurrent headaches. Typically, the associated headache affects one side of the head, is pulsating in nature, may be moderate to severe in intensity, and could last from a few hou ...

autoimmune disease An autoimmune disease is a condition arising from an abnormal immune response to a functioning body part. At least 80 types of autoimmune diseases have been identified, with some evidence suggesting that there may be more than 100 types. Nearly a ...

fibromyalgia Fibromyalgia (FM) is a medical condition defined by the presence of chronic widespread pain, fatigue, waking unrefreshed, cognitive symptoms, lower abdominal pain or cramps, and depression. Other symptoms include insomnia and a general hyp ...

, macular degeneration, cataracts, retinitis pigmentosa, complications from an eye operation, depression, chronic anxiety and others. She has also claimed that a treatment for scotopic sensitivity syndrome could help a number of incarcerated individuals and delinquent children.

Criticism

The Irlen method has been criticised for 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—even though those with visual stress are spread around the world, mostly don't know each other, and have no interest in Helen Irlen, all of which conditions would need to be met to fulfill the criteria of group dynamics. A 2002 study by Professor Arnold Wilkins at Essex University, though, indicates that there may be some benefit for reading difficulties , and also for people with migraines.

References

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