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Visual Stress

Dyslexia is a common problem many children and adults don’t even know they have. It is estimated that in the UK, every 1 to 10-20 people suffer from some level of dyslexia.

Dyslexia is not a disease, it’s a condition that you are born with. It is a difference in the way the brain works; a difference that will be present throughout your life. Dyslexia mainly affects reading and language skills and the effects can range from mild to very severe. The sooner dyslexia is spotted, the sooner suitable learning and coping strategies can be employed to minimise the effects of the condition.

Visual stress and reading

Dyslexia diagnosis is made by either an educational psychologist or a qualified specialist dyslexia teacher. Our role, as optometrists, is to identify and treat any visual problem that may be associated with the dyslexia. It has been suggested that there are higher levels of binocular vision problems and visual stress in people with dyslexia that contribute to their reading difficulties.

Symptoms of both binocular vision problems and visual stress can often overlap. Some examples of symptoms include:

  • Merging together of words/sentences
  • Double vision
  • General eye strain
  • Blurriness around the letters or words
  • Colour fringes around text
  • Extra spaces between words
  • Words appear bunched together
  • Words appear to be wavy and not in a straight line
  • Headaches from reading

Binocular vision problems

There are many types of binocular problems that can be caused by ocular misalignment or strabismus, ocular motility anomalies, convergence and accommodation deficits. These problems are identified in an orthoptic assessment and can be treated with exercises or with manipulation of the glasses or contact lens prescription.

Visual stress

Pages of print can resemble a visually stressful pattern, print can appear very stripy and can be uncomfortable to look at. This discomfort is defined as visual stress. It is thought that this visual stress is caused by a hyper excitability of neurones in the visual cortex. This means that some of the cells in the part of the brain that deals with processing of visual information work too fast or are over excited and therefore do not respond in the way they should to process information in a normal fashion.

Help for visual stress sufferers

Coloured spectacle lenses have been shown in some cases to benefit those with visual stress, headaches, migraines and photosensitive epilepsy. We know that certain cells in the visual cortex are sensitive to specific colour wavelengths, so by placing a colour filter in front of the eyes, the pattern of excitation can be changed. In other words, the colour will help to slow and calm these cells, therefore quietening the pattern and reducing the visual stress. The colour needed to reduce the hyper-excitability is very precise and individual to each person.

In addition, research in the US undertaken recently by a team of neuroscientists, using brain imaging, has shown that those who suffered from migraines had a vast improvement when individually selected precision tinted lenses were worn. Symptoms of other neurological conditions such as Autism, MS, ME and Parkinsons have been shown to reduce with the application of a precise colour.

Choosing a coloured lens for visual stress

Visual Stress can be reduced by the use of coloured filters. This works by placing a coloured overlay directly over text, or by wearing coloured lenses in spectacles. The reduction occurs only when the colour is selected to suit the individual.

In order to determine the precise colour tint for glasses to improve symptoms of visual stress, we use the Intuitive Colorimeter. The Intuitive Colorimeter is a machine that allows us to apply different colours upon text whilst adjusting the hue and saturation level until a specific colour is identified that will provide comfort when looking at text.

Contact lenses for visual stress

For those who have debilitating visual stress and require tint correction throughout the day, we can provide Cerium contact lenses. These are soft lenses where the centre is tinted with the specific colour as determined by Colorimetry and can correct your prescription at the same time.

Watch the Video to See How We Helped Kara Tointon


Nigel Burnett Hodd examined Kara's eyes