Colorimetry

Coloured lenses may help patients with severe pattern glare which, when it affects text is known as Visual Stress. It used to be thought to be more common in people with dyslexia but this has been disproved.  The latest estimates are that visual stress is present in around 1 in 5 people with dyslexia, but although they may co-exist, visual stress and dyslexia are different conditions.  However, if people with visual symptoms also have Dyslexia then it follows that these are likely to exacerbate their difficulty with learning from visual material (SASC SpLD and Visual Difficulties report 2018). Visual stress is sometimes called Meares Irlen syndrome, Irlen Syndrome or Scotopic Sensitivity Syndrome.

 

Some people who suffer from visual stress find that their symptoms are alleviated by coloured filters, either in the form of coloured overlays or tinted lenses. Tinted lenses are normally only considered once a sight test has been performed, and any other potential causes of visual difficulty have been addressed.

 

Visual Stress symptoms may include perceptual distortion, eye strain and headaches in certain patients, and may significantly reduce the incidence of migraine and photosensitive epilepsy.

 

At Paul Adler Optometrists we can apply precision tints to lenses on both prescription and non-prescription lenses. To determine which tint will have the most beneficial effect we measure reading fluency with different tints using our Intuitive Colorimeter. The instrument was developed by Professor Arnold Wilkins under the auspices of the Medical Research Council. More information about the research behind colorimetry can be found here.

Before prescribing precision-tinted lenses for patients, we usually recommend using a coloured plastic overlay when reading for a trial period and we usually measure speed of reading with and without colour. This enables us to establish whether a coloured tint will result in significant and sustained improved reading fluency and/or improved visual comfort before supplying a Precision Tinted Lens.

 

Assessment for the benefits of coloured filters and Precision Tinted Lenses are not available on the NHS.

 
 
 
 
Visual Stress Symptoms

The children most likely to benefit from coloured lenses will often show some of the following symptoms:

  • Headaches during or after reading

  • Rubbing eyes

  • Watering or red eyes

  • A marked dislike of bright light (photophobia)

  • A tendency to constantly shift or alter position of text whilst reading

  • Complaining of fatigue after a short period close work

  • Print appearing to be blurred, moving, flickering or fading

  • Appearance of patterns in the print colours appearing around print

  • Doubling of letters or words 


Care needs to be taken in assessing these symptoms, since many of them are associated with problems of focusing (accommodation) and with binocular vision or other vision perception problems. For this reason, it's generally advisable for patients experiencing these symptoms to have a full examination by an optometrist skilled both in binocular vision assessments and in dealing with children’s vision problems. For more information about the specialist work we do with children's vision problems, click here.

 

Adults & Visual Stress

Many adults suffer from exactly the same problems as children. Indeed children with unsolved problems become adults with unsolved problems. Precision-tinted lenses and vision therapy are effective for both children and adults. Click here for more information on vision therapy.

 

 

Migraine and photosensitive epilepsy

There is increasing evidence that the use of precision tints for those with some types of migraine and photosensitive epilepsy can be of real help in reducing or alleviating their symptoms. We have helped many such patients and are always happy to discuss the technique if you think it might help you.

 

Traumatic brain injury

Many patients have also found precision-tinted lenses of considerable benefit following accidents or strokes that leave them unable to concentrate on close work. There can be many complications in these cases, and this method is unlikely to help everyone; however we are happy to discuss details of individual difficulties and advise if this approach may be of help.