What is Scotopic Sensitivity Syndrome?

also called Meares-Irlen Syndrome, Visual Stress or Visual Snow


Words 1: snowy text on a page

Scotopic Sensitivity Syndrome also referred to as Irlen Syndrome after Helen Irlen, who in the early 1980s discovered that some people with poor reading showed a marked and immediate improvement by overlaying the pages of text with a coloured semi-transparent plastic sheet. Furthermore, in the early 1980s New Zealand teacher Olive Meares independently described the visual distortions some individuals reported when reading text on white paper hence Scotopic Sensitivity Syndrome is also known as Meares-Irlen Syndrome. Additionally the condition is sometimes called 'visual stress' (n.b. the underlying condition is not caused by mental stress or anxiety). Informally, this condition is often referred to as 'visual static', 'visual snow' or 'snowy vision'.

Words 2: snowy text on a page

Scotopic Sensitivity Syndrome is a neurological condition (not a learning disability) caused by the brain and/or eye incorrectly processing/interpreting what the eye is seeing. Some estimates suggest that, to varying degrees, up to 12% of the population may experience these visual disturbances. Scientific knowledge has not yet advanced enough to fully describe the neurological mechanisms causing these visual disturbances. Often, but not always, Scotopic Sensitivity Syndrome afflicts people with Dyslexia or Autism Spectrum Disorder. In general people with Dyslexia may have problems seeing text on a page. Whereas people on the Autism Spectrum, although perhaps able to read, may have problems with correctly interpreting their surroundings due visual defects such as Scotopic Sensitivity Syndrome. For unknown reasons some people appear to develop visual snow in adulthood, especially during their late teenage years or early twenties.

Words 3: snowy text on a page

Standard eyesight tests performed by an optometrist do not routinely detect visual snow since they are not designed to detect this condition. Furthermore many medical professionals (eg. local family doctors, neurologists) and educationalists are unaware of Scotopic Sensitivity Syndrome and its effects (eg. headaches from reading). Conversely, awareness of this condition is now much more widespread and it is recognised by many employers (esp. large companies), educational institutions and schools. Anyone experiencing a significant degree of visual snow will have increased difficulty reading and studying.

The main symptoms associated with Scotopic Sensitivity Syndrome are:

...experience Scotopic Sensitivity Syndrome for yourself!