Visual Stress Information and Symptoms

Visual Stress was originally identified in the early 1980s by Helen Irlen in California and Olive Meares in New Zealand, who both independently discovered the connection between white page "glare" and reading difficulties at around the same time. The condition is also called Scotopic Sensitivity Syndrome, although scientifically it has now been shown that this is not a very accurate term, as it refers to an area of the visual system that is not actually affected by the condition. Visual stress is the name that is most commonly used in the peer-reviewed research published in the UK, much of which can be found at

So what is Visual Stress? The problem is visual-perceptual in nature, most probably originating in the visual cortex of the brain, arising from the over-sensitivity of specific cells in the visual cortex to specific light wavelengths. Filtering out those wavelengths with a precision tinted coloured overlay or reading ruler (or lenses: if the parents can afford them and the child will wear them, these are the best option) that matches the profile of the individual, "calms down" that area of the brain and eliminates the distortions and discomfort (see list below) that cause reading difficulties for people with Visual Stress. Because it is perceptual, rather than visual in nature, it is not corrected by prescription glasses, and it cannot be detected by standard visual, educational or medical tests.

How do you know if you have Visual Stress?

Symptoms of Visual Stress vary, but can include headaches and migraines (especially when working at the computer), eyestrain, and words or letters appearing to "jump" or move on the page. People who have VisualStress see the page differently because of distortions of the print or white background.

In general, somebody with Visual Stress may

  • Experience difficulty looking at a computer screen
  • Be unusually sensitive to bright lights, especially flourescent lighting.
  • Have difficulty judging heights or distances, which sometimes causes problems with stairs and/or escalators.
  • Find driving at night particularly stressful, sometimes experiencing a fragmentation of reflected light.
  • Develop headaches and migraines when reading.

Some, or all, or the following can be noted while reading. Sufferers may:

  • Fatigue quickly when working with text
  • Experience problems copying from the board
  • Skip words or lines when reading
  • Seem to experience increased difficulty after an initial period of about 10 minutes
  • Keep moving their head or body position, or moving closer to or further away from the page
  • Read slowly and haltingly and have difficulty absorbing information
  • Track with the finger
  • Yawn while reading.
  • Frequently rub their eyes.

Visual Stress typically causes the following distortions of print, although not all of the following will necessarily be experienced by one person:

  • The print appears to jump or otherwise move on the page - sometimes appearing to move off the page altogether.
  • Swirling effects appear in the text.
  • Whole lines of text may appear to move.
  • Shimmering colors may appear on the page.
  • White "rivers" may seem to run down the page, where the white background, as opposed to the black text, has become the dominant image perceived.
  • Letters may double, reverse, fade or blur. Basically the image of the letters and words is unstable against the white background, and this instability can be experienced in a number of ways.

Does Visual Stress go away?

Generally, no; although there are cases reported where the contrary has been the case. Sensitivity does seem to change though, especially in a changed response to colored filters. Somebody who has found a particular color most beneficial may find that this preference changes and a different tint will be more helpful.

What can be done?

People with Visua lStress can read with much greater ease if they cover a print with a specially treated colored overlay. Screening can help to identify which color is most beneficial. Crossbow Education supply convenient reading rulers and the larger A4 size colored overlays in ten colors that have been carefully selected to cover the full spectrum in different combinations. Crossbow also supply the Visual Stress Assessment Pack for thorough screening of individual color preferences.

For any optical difficulties, it is important that an optometrist is also consulted to ensure that there are no underlying medical or ophthalmic conditions. Some optometrists prescribe colored lenses, and have specialist equipment to test for color preference. It is often found that lenses of a different color from the overlays are needed.