Visual stress, also known as Meares-Irlen Syndrome, is a disorder in visual perception making reading difficult, uncomfortable and frustrating for sufferers. it can affect children and adults alike and both those who wear spectacles and those that don't. Common symptoms are distortion of text, glare, eyestrain and headaches and visual migraines.

From recent research it is thought that as many as 1 in 5 children in mainstream education are affected to some extent with 1 in 20 suffering quite severely. Sufferers often underachieve because their experience of reading is unpleasant.

It is likely that sufferers, especially children, do not report the way they see things as they consider what they see to be "normal" and it is only when they are shown otherwise that the signs and symptoms of Visual Stress become apparent.

By changing the background colour of what is being observed sufferers should notice an improvement in the clarity and sharpness of what they are looking at. After thorough assessment the patient will be issued with a colour transparent sheet of plastic (an overlay).

If, after a trial period, the coloured overlay is found to be beneficial, further assessment can be done to determine a colour that is suitable to be replicated in spectacle lenses. This allows the benefit of the colour to be used when observing things at all distances. The colour, and intensity are very specific to the person being tested and can vary over time.