Scotopic Sensitivity Syndrome - 'Meares–Irlen syndrome'

Scotopic Sensitivity Syndrome also referred to as Irlen Syndrome after Helen Irlen, who in the early 1980's discovered that some people with poor reading showed a marked and immediate improvement by simply overlaying the pages with coloured plastic (e.g. acetate sheets).

Furthermore, in the early 1980s New Zealand teacher Olive Meares independently described the visual distortions some individuals reported when reading from white paper hence Scotopic Sensitivity Syndrome may also be referred to as 'Meares–Irlen syndrome'.

Additionally the conditions is also refered to as 'Visual Stress' but the underlying condition is not caused by stress or anxiety.

It is believed that this condition affects, to varying degrees, approximately 12% of the population.

It is a neurological condition which causes the brain and/or eye to incorrectly process or interpret what the eye is seeing.

People with this condition will have increased difficulty reading and studying. Unfortunately standard sight tests and many educational assessments do not routinely detect this condition.

Fortunately, awareness of this condition is now much more widespread and it is recognised by many employers (esp. large companies), educational institutions and schools.


The main symptoms of Scotopic Sensitivity Syndrome are:

• Light Sensitivity causes discomfort or difficulty under the following conditions:
• glare from lights (e.g. from on-coming headlights on cars)
• glare from surfaces (e.g. glaring spots of sunlight on cars)
• bright lighting
• fluorescent lights - including energy saving bulbs
• sunlight
• night vision

Contrast problems occur when difference between light and dark is very pronounced, for instance:
bold black text on bright white paper. The text or the background may appear to move, sometimes violently.

• vertical or horizontal window blinds where the contrast between the blinds and outside world can be significant. The blind may appear to move and/or the sufferer may not be able to see through the blinds clearly.
• stripy patterns and bold patterns such as those on some clothes, carpets, wallpaper, posters etc. can appear to move/vibrate and some patterns may appear to be three dimensional instead of flat.

These effects make reading such things as text, music, graphs, maps much more difficult and potentially tiring. Since wallpaper, carpets and clothes can also cause discomfort the world can feel a very harsh place.

Restricted field of clear vision
This causes only a few letters on a page appear clear and the rest of the page appears slightly out of focus (these focusing problems are not due to short/long sightedness or any physical problem with the eye)

For example when reading a sentence the sufferer can sometimes only clearly see a couple of letters at a time.

Depending on the severity of the condition this will severely limit the persons ability to speed read or skim through a page of text.

Being unable to physically clearly see whole words makes it harder to identify them quickly. Hence it is hard to instantly recognise words if only part of a word is seen clearly which makes learning to read extremely difficult.

Scotopic Sensitivity Syndrome makes it more difficult to keep track of where you are on the page.

It is very easy to accidentally start reading the line below or above, or the words/letters in the wrong order. It is also hard to find the next line to be read. I often either skip or re-read a line.

Suppose if when teaching a child to read every time they are shown a given word they see a different part of the word because they can’t simultaneously see all the letters - so learning to read becomes nearly impossible.

Poor Depth Perception causes difficulty with judging the distance and the relationship between objects.

A lack of depth perception can cause problems with such things as difficulty with ball sports, escalators, walking and bumping into objects, driving/cycling and judging heights (I have no perception of height and have no fear when looking over bridges, cliffs etc.)


Attention and concentration difficulties as a result of these visual distortions.

Scotopic Sensitivity Syndrome impairs the ability of the individual to read, study and work efficiently and it often causes our eyes to feel uncomfortable.

This lack of attention will probably display itself in one or more of the following ways:

• difficulty staying on a task such as reading or studying
• taking frequent breaks
• restlessness
• tiredness

Headaches and Migraines: a Scotopic Sensitivity Syndrome sufferer is much more susceptible to headaches and migraines brought about by the visual distortions they are experiencing.