Assistive technology and tools 
for learning difficulties, migraines 
and other neurological differences 


Signs and symptoms  

The primary indications of Visual Stress appear as reading and learning difficulties and are both physical and perceptual in nature.  Visual Stress can affect what people see and how they feel.  Following is a list of some of the effects that may be felt.  Note that individuals may feel the effects from only one group or both and the extent to which they feel them may range from mild to strong. 


Perceptual effects include:  


Instability of Text where words appear to: 

·         Move into patterns (rivers)

·         Swirl

·         Shake

·         Vibrate

·         Double up

·         Blur in and out

·         Washout

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Illusions of colour and light where: 

·         Colours appear between or around letters

·         Colours appear on the edges of the page

·         Lights flicker behind the text or image

·         Colours flicker and flash in the entire viewing area


Hypersensitivity to repetitive patterns where it is difficult to look at: 

·           Heavy concentrations of text on a page

·           Stripes, including venetian blinds, escalator stairs, and bad ties.

·           Fabric patterns, including hounds tooth or other small geometric patterns.

·           Spreadsheets and tables of data, including multiplication tables for children.


Depth Perception difficulties where:

·         Door frames, table corners and other objects in your path are often bumped into.

·         Learning to ride a bicycle is difficult

·         Athleticism is not a problem, but ball play is difficult.


Physiological effects: 

·         photosensitivity,

·         headaches,

·         sore eyes,

·         nausea

·         fatigue

·          pain in or around the eyes

·         blurred vision,

·         and occasional double vision


Effects range from mild to severe, and can interfere with ability to learn to read, with reading fluency, and notably with the ability to read in a sustained manner for long periods of time.


Unfortunately, but since it is not picked up in standard optometric, psychological or health exams, it is often overlooked as the cause (or part of the cause) of the individuals problems. As well, many of the symptoms are similar to those of other conditions and may be misinterpreted as, for example AD/HD or Dyslexia, and treatment that may otherwise be unnecessary, is undertaken.


Placement of a coloured overlay on the troublesome white page, or the wearing of coloured lenses, has been found to neutralize the unpleasant visual symptoms (e.g. Robinson and Conway, 2000; Kriss and Evans, 2005). The effective colour varies from person to person.