Scotopic sensitivity syndrome, also known as Meares-Irlen syndrome or Irlen syndrome, is a broadly defined visual perceptual disorder affecting primarily reading and writing based activities. Because of this, it is sometimes categorised as a form of dyslexia.

The condition was jointly described by two people working individually, unaware of the work of the other person. In the early 1980s New Zealand teacher Olive Meares described the visual distortions some individuals reported when reading from white paper, while American psychologist Helen Irlen wrote a paper about the use of coloured overlays aiding the reading abilities of some people. Irlen named her findings "scotopic sensitivity", though the discussions and debates over the following years often referred to it as Meares-Irlen Syndrome.

Theory

Scotopic Sensitivity Syndrome is based on the theory that certain wavelengths of light interfere with the visual pathways between the eye and the brain.

Symptoms

• Light sensitivity and contrast problems. People with strong symptoms of the syndrome find it very difficult to read black text on white paper, particularly when the paper is slightly shiny.
• Restricted field of clear vision
• Poor depth perception
• Attention and concentration difficulties

Treatment

The use of tinted lenses in glasses and coloured overlay sheets has been prescribed by many doctors, however, the efficacy of such treatment is questionable.

Irlen Method

• Tinted lenses
• Tinted overlays

Skepticism

Critics claim that the symptoms of those with Scotopic Sensitivity Syndrome are related to already known visual disorders. According to a statement released by the American Optometric Association in 2004[[1]]: "There is evidence that the underlying symptoms associated with the Irlen Syndrome are related to identifiable vision anomalies, e.g., accommodative, binocular, and ocular motor dysfunctions, in many patients seeking help from colored lenses. Furthermore, such conditions return to normal function when appropriately treated with lenses, prisms, or vision therapy. When patients exhibiting the Irlen Syndrome were treated with vision therapy, their symptoms were relieved. These patients were no longer classified as exhibiting this syndrome, and therefore did not demonstrate a need for the colored overlays or tinted lenses."

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