Optician India

Welcome to question of the day #150

One of my patients, a 10-year-old boy has been advised by his teacher to have an eye examination. He is an intelligent pupil when it comes to verbal school work but when it comes to reading he struggles. The teacher has estimated that the boy reads at the level of a 7-year-old? I have examined him and he has pattern glare. He has been reading better with a rose coloured overlay and now wants tinted lenses. What should I do?

Some people who struggle to read and improve when reading with a coloured overlay prefer to continue with the overlay. Of course, the coloured overlay is only useful for reading print in books and similar material and it cannot be used for board work.

Some people prefer to use tinted lenses. These can be used for reading from books and similar and also for board reading and copying from the board. Some eye specialists will take the colour from a coloured overlay and convert this to a tinted lens. Good research has shown that this is not in the patient’s interest. A tint copied from a coloured overlay is very unlikely to help a person with pattern glare. This should not be done.

Overlays sit on the page and the only thing that is coloured is the overlay and the page it sits on. The visual system is still aware of other colours and there is no colour constancy. When a person looks through a tinted lens everything is coloured and there is colour constancy. A banana still looks yellow when it is viewed through a red tinted lens. This is an example of colour constancy.

A good way of determining the colour of the optimum tinted lens is to use a colorimeter. See figure. Another reason for not simply copying the colour of a successful overlay to a tinted lens is because overlays are usually limited to a few colours whereas with colorimetry thousands of colours are available. Each person with pattern glare will need a very precise tint-their own tint-which wll differ from other people with pattern glare.

Precision tints are best used for educational activities and leisure reading. People who use tinted lenses still need help with their learning. Some tints may look like a sunglass tint but these should not be used for sun protection unless a UV filter is incorporated.

The tint will help the print look normal but there has to be some reading remediation to help the person catch up and get to their proper reading age.

People who are prescribed tints for pattern glare should be reviewed in six months time. Sometimes the colour of the tint needs to be refined after six months in order to get optimum effect on getting rid of the perceptual distortions.