Colorimetry & Visual Stress

Visual stress is a term used to describe visual discomfort and perceptual distortions in printed text, suffered by many people who struggle to read. The condition is estimated to be present in about 40 % of poor readers and in 20 % of the general population in varying degrees.

Coloured overlays can improve reading speed and accuracy. They can enable longer periods of reading free of discomfort. When they do, it is an indication that the individual may benefit from Precision Tinted Lenses. The lenses are prescribed using specialist equipment called a Colorimeter. Recent imaging studies suggest that the symptoms of visual stress may be caused by a hyper-excitability of the visual cortex in the brain. The problem may be linked to photophobia and migraine.

Dyslexic individuals are more likely to experience visual stress than others, although visual stress is quite distinct from dyslexia and the phonological difficulties with which dyslexia is usually associated.

Many thousands of individuals who find reading tiring and unpleasant, unknowingly experience visual stress.

They have to work harder than their peers to achieve the same outcomes, often with extra tuition. Many could be helped by overlays or Precision Tinted Lenses. It is therefore essential that every child who struggles to read is referred to a vision practitioner who can undertake a full eye examination and check for the presence of visual stress.

A diagnostic process has been designed that allows for the identification of visual stress, thereby distinguishing it from other barriers to reading. This is achieved by the simple selection of an optimum coloured overlay placed over the reading matter.

The Signs and Symptoms of Visual Stress

All or some of the following may be present:

  • Movement of the printed text
  • Patterns in the print (described as rivers or worms)
  • Tiring easily whilst reading
  • Headaches or visual discomfort
  • Using finger as a marker on the page
  • Frustration and low self-esteem
  • Migraine

Intuitive Colorimeter

The Intuitive Colorimeter is used extensively by vision professionals across the UK. Under the direction of our Optometrists, we guide patients in selecting an ophthalmic tint that reduces discomfort and perceptual distortion. An examination with the Colorimeter lasts about 20 minutes and enables the effects of hue, saturation and brightness to be explored systematically and efficiently whilst the eyes remain colour adapted. With the help of proprietary software, tinted trial lenses are then combined to assess the clinical benefits of the chosen colour under conventional lighting. The shades available enable the tint to be precisely tailored to an individual’s needs. The prescribed tint is reproduced precisely in specially designed laboratories.

The system also allows for alternative colour combinations for use under different lighting conditions and includes UV and Blue Light transmissions. It also takes account of the effects of colour on traffic signals.