Colourimetry and Overlay

This is the measuring of colour and using specifically tinted filters (overlays –that are transparent sheets tinted to the specific colour in order to emit a spectrum of light), to relieve the symptoms of conditions associated with visual stress and migraine.

Professor David Thompson was Frederick’s personal tutor at City, University of London whilst Frederick was studying optometry. Professor Thompson went on to lead the department and later to develop a range of facilities such as the Thompson computer system, to help the profession diagnose visual stress.

The Thompson system does this by determining which colour is optimum for use with an overlay or coloured prescription lenses. In so doing, we aim to help some of the 20% of the population who suffer from discomfort when looking at regular patterns where words appear to move, wobble or flicker. This helps to increase the reading speed, fluency or a dislike of reading of those who have visual stress.

The reasons for the overlays effectiveness remain not well understood. It is known however that by changing the background colour of the text, the symptoms of visual stress have been reduced and in some cases eliminated. While some colours prove more successful than others, the colour which minimises the symptoms seems to differ between individuals.