Frequently Asked Questions


What is Visual Stress?

A condition contributing to reading difficulties, eye strain and headaches when reading. It can be responsible for light sensitivity, appearance of patterns in the text and glare effect.

What causes the Visual Stress?

The hypothesis is that the stress is due to a hyper excitability of the neurons in the visual cortex, an area of the brain at the back of the head, which fire inappropriately. In other words these cells kind of work a bit too fast which causes the disturbances in the text.

Is visual stress the same as Dyslexia?

Visual stress can be due to a number of conditions including Dyslexia, but is not the same.

What are the symptoms of Visual Stress?

  • glare
  • headaches when reading
  • movement/blurring of print
  • eye ache
  • rapid tiring

What are the signs of Visual Stress?

  • rubbing eyes
  • increased blink rate
  • poor concentration
  • using finger as marker
  • low self esteem

Can adults be affected?

As people get older and text is not such a meaningless group of words, Visual Stress can be less pronounced, but still there. In a lot of cases the syndrome goes undiagnosed and untreated until adult life.

What are coloured overlays?

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 patient. They can alleviate some of the visual stress, making reading more comfortable. Each child will benefit from a different colour. To assess the benefit with the chosen colour the Wilkins Rate of Reading test can be carried out.

What if overlays are helpful?

If the child continues to use the overlay, unprompted, or the teacher/parent reports an improvement it has most likely been beneficial. The overlay is usually given as a trial period for approx. 6 weeks to rule out novelty factors. Glasses with coloured lenses can then be prescribed. These are more convenient as they can be used with board work. The tint is a much more precise tint as many more colours combinations are used. Again the tint will vary from person to person.

How can I get coloured lenses?

The colour of the lenses can only be assessed by using The Intuitive Colorimeter, which uses a much larger range of colour combinations than used with the overlay assessment. This therefore gives a much more accurate colour specific to each patient. This is usually carried out by an Optometrist or Orthoptist and the test takes about 20 -30 minutes. When you wear glasses the whole of your visual field is coloured ie you are fully adapted to that colour. The Intuitive colorimeter takes account of this and tests in the same way so that no other colour of light is involved. Overlays on the other hand only cover part of your visual field therefore white light plays a big part. The colour of the lenses are hence different to that of the overlays due to the colour adaptation factor

Where can I get assessed for coloured lenses?

You will need to visit a specialised Optometrist who will have the Intuitive Colorimeter. You firstly need a full eye examination. This will check for any uncorrected refraction problems or any binocular anomalies. If found, these are corrected before proceeding with the use of colour.

Can you have perfect eyesight and still experience visual stress?

YES, perfect eyesight means you can read all of the letters on the chart without glasses and both of your eyes work together in the way they should. Visual stress can come from a binocular anomaly, but this will be corrected before any colour is used. If Visual Stress is still occurring after all binocular problems have been sorted the cause is likely not to be due to the eyes but the visual cortex part of the brain. Colour is likely to help on these cases.

Cerium focuses on the problem and comes up with tangible solutions.
ISO 9002: 1994 Certificate No: FM 33565