What is Visual Stress?
In A Nutshell
In more detail
Visual stress is a common condition of the visual cortex which is often experienced by people with dyslexia, but is a separate and distinct condition. Apparent movement and distortion of text, headaches and sore eyes are common symptoms of visual stress. Coloured overlays were shown in 2001 to improve reading experience for about 20% of the population; a 2019 study showed that the figure could be much higher. Visual stress has some common misnomers, particularly "Scotopic sensitivity" (which suggests that it is a condition of the retina and not the visual cortex), and "visual dyslexia", which confuses the cognitive processing (dylexia) with visual processing (visual stress). Visual stress will create extra difficulties for a dyslexic person by making words hard to decipher, but once a reading ruler or overlay has made them visually clearer they still need to be decoded, and that is where dyslexia causes its problems..
Because visual stress is perceptual, rather than optical, 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 Visual Stress see the page differently because of distortions of the print or white background.
In general, somebody with Visual Stress may
Some, or all, or the following can be noted while reading. Sufferers may:
Visual Stress typically causes the following distortions of print, although not all of the following will necessarily be experienced by one person:
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 coloured filters. Somebody who has found a particular colour most beneficial may find that this preference changes and a different tint will be more helpful.
What can be done?
People with Visual Stress can read with much greater ease if they cover a print with a specially treated coloured overlay. Screening can help to identify which colour is most beneficial. Crossbow Education supply convenient Reading Rulers and the larger A4 size Coloured Overlays in ten colours 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 colour 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 coloured lenses, and have specialist equipment to test for colour preference. It is often found that lenses of a different colour from the overlays are needed. A list of specialist optometrists and Irlen centres can be found here.