When you wear coloured glasses everything you see is coloured, but you are often unaware of the colouration because you adapt to it and make allowances for it. When you use an overlay only part of what you see is coloured and the eyes adapt to white light. The way that the brain processes what you see in the two circumstances is very different. Research shows that different people need different colours and the optimal colour for each individual needs to be prescribed with precision. The Intuitive Colorimeter is designed to assist in finding the optimal colour and is widely used for this purpose.
Not necessarily. It is important to note that scientific research has established the appropriate colour of the chosen lenses is not the same as that of the chosen overlay. For example a child may choose a yellow overlay and benefit from green lenses. The colour of the lenses can only be assessed by optometrists who use the Intuitive Colorimeter, or by using a very large number of trial lenses. Other methods of selecting coloured lenses may be less likely to achieve the optimal colour and give the optimum improvements.
The optimum colour (whether for overlays or precision tinted lenses) can change over time, especially in children. It is recommended that children with visual stress undergo a colorimetry test every year. The colour is less likely to change in adulthood and usually colorimetry is only repeated for adults if they feel that the benefit from their current colour is wearing off.
A Colorimeter practitioner is unlikely to prescribe lenses for any child who does not benefit from using them for literacy tasks. The child should be free to wear the lenses for other activities if they find it helpful to do so. They should not be coerced however into wearing them if they would not otherwise do so. As some people suffer more severely from Visual Stress than others, the wearer is the best person to judge whether they derive any benefit from wearing them for other activities or outside.
The optometrist who prescribes the lenses is the person best positioned to advice if this is advisable. Colorimeter practitioners have access to computer software which allows them to calculate whether precision tinted lenses are safe to wear outdoors. The Highway Code recommends that tinted glasses are not used for driving at night.
Some children may cease to use overlays or lenses after one or two years. This may be because acquired familiarity with text makes the distortions less distracting. Other children, who may suffer from visual stress and photosensitivity more severely, may derive on-going benefit from wearing the lenses. Many adults continue to use the lenses.
Visual Stress is likely to always have been unknowingly present in individuals who suffer from the condition. Some individuals manage to struggle through their education without Visual Stress being identified. Such people may never have found reading to be a comfortable or natural experience. Some may have wrongly been labelled ‘dyslexic’.
Many people often report relief from symptoms when they eventually discover coloured overlays and/or Precision Tinted Lenses later in life. Some also report that their working lives are substantially improved by the ability to read more comfortably and at a swifter pace.
If you recognise any of the symptoms of Visual Stress mentioned on this website, it is never too late to be tested for the condition by a qualified Colorimeter practitioner.