Coloured Glasses - Meares–Irlen syndrome

"Children who persist in using their overlay usually find coloured glasses more convenient to use. Glasses can help with writing, whereas overlays cannot. The degree of precision in the choice of colour is critical for obtaining the best results, and the precision available with lenses is far greater than with overlays. Perhaps for this reason glasses often give better results.

It is essential to realise that the appropriate colour for use in glasses is not the same as that in overlays. For example, a child may choose a yellow overlay and benefit from blue lenses. The colour of the lenses can only be assessed by optometrists or orthoptists who use the Intuitive Colorimeter ®, or by the use of a very large number of coloured trial lenses. Other methods of selecting coloured lenses may be less likely to select the optimal colour.

When you wear glasses everthing you see is coloured, but you are often unaware of the colouration because you adapt to it and make allowances for it (for example, the colour of light from a normal household light bulb is very yellow in comparison to daylight, but you are never aware of this). When you use an overlay only part of what you see is coloured and the eyes are adapted to white light. The way that the brain processes what you see in the two circumstances is very different."