Chessboard Pattern Mirrors Eye Defects

April 13, 1999

Researchers at Vrije Universiteit Amsterdam (VU) have developed a new method of analysing corneal defects. In order to do this, they reflected a pattern of squares onto the cornea and recorded the reflection in the eye. The distortions were then compared with a coloured chessboard pattern. The measurements open up new possibilities for early diagnosis and treatment of a number of eye defects. The research was part of a project funded by the NWO's Netherlands Technology Foundation (STW).

The new measurement technique uses a pattern of squares on the inside of a transparent tube about the size of a wastepaper basket. The tube is illuminated from the outside by eight neon lights. When the patient looks into the tube, the illuminated pattern is reflected by the cornea and then recorded with a CCD camera. The pattern consists of black, yellow and blue blocks arranged in such a way that no blocks of the same colour touch one another and that each group of 6 x 2 coloured blocks is unique. This allows the optician to localise an eye defect with great precision.

Up to now, corneal topography has produced only limited results, partly because the surface of the eye cannot be immobilised. Moreover, eye surgery requires measurements of defects which are precise down to micron levels. The new Dutch equipment produces an extremely precise map of distortions in the eye. This is of eminent importance for cornea transplants or laser treatment. A prototype of the measuring equipment has already been constructed. The Amsterdam researchers plan to carry out further tests with the system and hope to miniaturise the set-up in order to make it more convenient and affordable.
Further information and coloured illustrations are available from
Dr G. van der Heijde (VU/Medicine)
T: 31-20-444-0286, F: 31-20-444-4147

Dr Franz Vos (VU) recently gained his doctorate for his work in this field.

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