Visual Stress Assessment

Visual stress can be attributed to a number of conditions including dyslexia. However, visual stress is not the same thing as dyslexia. Dyslexia is a term used to describe various specific learning difficulties that can affect the ability to learn to read and spell correctly. Visual stress can be particularly prevalent in Dyslexic individuals. If Visual stress is identified, colour can be used to alleviative some of the symptoms, then other learning difficulties such as Dyslexia are easier to cope with.

Many people with Dyslexia may also suffer from visual stress and can, therefore, be helped by colour. Equally, there are a large percentage of children and indeed adults who are not identified as being dyslexic but can still suffer from these symptoms. The appropriate coloured overlay can also help this group of individuals.

Sheets of transparent coloured plastic, to be placed over the required text. Used as a screening tool to determine if colour will be of benefit to each client. They can alleviate some of the visual stress, making reading more comfortable. Each client assessed will benefit from a different colour. To assess the benefit of the chosen colour an assessment will be carried out in practice, usually by our dispensing optician.

If the client continues to use the overlay, unprompted, or they report an improvement it has most likely been beneficial. The overlay is usually given as a trial period for approximately 6 weeks to rule out novelty factors.

Precision tinted lenses
The symptoms of Visual Stress can be reduced using coloured filters, such as coloured overlays placed over text, or if these prove inconvenient precision tinted lenses worn in spectacles.

Precision tinted lenses have also been shown to make a significant difference to the quality of life for Migraine sufferers. Symptoms of some other neurological conditions such as Autism and MS may also appear to be reduced with the application of a precision tint.

If you think you or your child has visual stress or that you may benefit from Precision tinted lenses there is a screening test available: providing detailed visual assessment and expert advice and treatment for difficulty with reading or visual stress. Assessments are available for children and adults.

  1. A full eye examination with one of our optometrists. Our optometrist will carry out a series of tests to check for any visual or eye health problems. These tests help to rule out any other causes of symptoms such as needing spectacles, or a binocular vision
    (eye muscle) problem. Our optometrist will also look at the eye in detail to make sure it is healthy. This part is essential even if a recent eye examination has been carried out elsewhere as it contains tests that may have not been performed as part of the standard eye examination.
  2. An overlay assessment. This appointment is usually carried out by a dispensing optician. We have a range of overlays (coloured perspex sheets) to try. Each sheet is tried in turn to determine which gives the most comfortable and effective rate of reading. We measure the reading speed with and without the overlays in place to see if any benefit is obtained.
  3. Cycloplegic examination At the end of this appointment cycloplegic drops are often instilled
    into the client’s eyes, particularly in children and young adults. These drops relax the accommodation and take about thirty minutes to work. Vision will be blurred for a few hours after the examination.

Following the eye test, the client may be prescribed with spectacles or an overlay. In this case there will usually be another appointment arranged for six weeks time to see if there has been any improvement.

The term Visual Perceptual Distortions refers to a group of distortions that in some cases appear in printed text. These distortions are often perceived by individuals suffering from Visual Stress. The words appear to move or to blur, sometimes white “rivers” appear in the back white text. These are just some of the distortions reported by those who struggle with reading and who could be suffering from Visual Stress.
Different people experience different problems with text, but generally, they report difficulty with small repetitive black print on a stark white page. Distortions such as these, even though perceived, can often cause hesitation in reading. Some people demonstrate a slowing in or a need to cease reading. In some cases children may not wish to look at a book because of the distortions experienced can cause discomfort.  In some cases when a coloured overlay has been introduced the individual may they feel more comfortable viewing the text.

When wearing coloured glasses everything viewed is coloured, but many people adapt to it and make allowances for it. When using an overlay only part of what is viewed is coloured and the eyes will adapt to white light. The brain processes what we see and the two circumstances are very different. Research has shown that different people prefer different colours. To find the optimal colour for each individual the assessment needs to be carried out with the utmost precision. By using the Intuitive Colorimeter the exact colour and hue can be prescribed.

Not necessarily. Scientific research has established that the appropriate colour of the chosen lenses may not be the same as that of the chosen overlay.  For example, an individual may choose a green overlay and benefit from blue lenses.  The lens colour should only be assessed by optometrists who have received training in the use of the Intuitive Colorimeters. Other methods of selecting precision tinted lenses may be less likely to achieve the optimal colour and give effective results.

Yes, (whether for overlays or precision tinted lenses) the colour can change over time, particularly in children. We recommend that children with visual stress undergo a colorimetry test every year. The lens colour is less likely to change in adulthood. Usually, colorimetry is only repeated for adults if they express that the benefit from their current colour is wearing off.

A practitioner is unlikely to prescribe lenses for anyone who does not benefit from using them for literacy tasks. The individual should be free to wear their lenses for other activities should they find it helpful to do so. Activities such as reading music can be helped by using precision tinted lenses.  But no one should be coerced into wearing them if they do not wish to do so.  Some people suffer more severely from Visual Stress than others. The wearer is the best person to judge any benefit from wearing them for their other activities or outside.
The optometrist who prescribes the lenses will advise on wear time and use if appropriate. Colourimetry practitioners have access to dedicated computer software which allows them to calculate if precision tinted lenses are safe to wear outdoors. The Highway Code recommends that tinted glasses are not used for driving at night.

Some children do cease to use overlays or lenses after one or two years. This could be because they have acquired familiarity with text making the distortions less distracting. Other children, such as those who may suffer from visual stress and also photosensitivity, may derive on-going benefit from wearing their coloured lenses. Many adults will continue to use the lenses.

Yes, visual Stress is likely to always have been unknowingly present in some individuals who suffer from the condition. Some individuals do manage to struggle through their education without Visual Stress ever being identified. These people may find reading uncomfortable. Some may have wrongly been labelled as ‘dyslexic’
These people often report a feeling of relief from symptoms when they discover coloured overlays or Precision Tinted Lenses later in life. Some report that their working lives are improved by the ability to read more comfortably and at a quicker pace.
If you recognise any of the many symptoms of Visual Stress mentioned, it is never too late to be tested for the condition by a qualified Colorimeter practitioner.

Precision tinted lenses may help to prevent migraine attacks. More often they enable patients to continue with their daily activities and to cope in uncomfortable environments.

Other neurological conditions have also been shown to benefit from using Precision Tinted Lenses. Research has shown that reading can, in some cases, improve significantly in those on the Autistic spectrum with the use of a precision colour.  Acquired brain injury sufferers have also, anecdotally, shown to benefit with a chosen colour.

This work is ongoing.

A Little Caveat

We would like to make it clear that successful treatment of visual stress IS NOT a cure for dyslexia or any learning difficulty. Reading through colour is just a start to relieve a symptom and a tool to help a client cope with their condition.

If you would like an information pack, or to book an assessment call the team at Allegro Optical on 

Meltham – 01484 907090 or call into Allegro Optical, 1-3 Station Street, Meltham, Holmfirth, West Yorkshire, HD9 5NX 

Greenfield –  01457 353100 or call into Allegro Optical, Unit 1 The Greenfield Centre, Wellington Rd, Greenfield OL3 7AJ