Quick Dips

Keeping an Eye on the Brain

The notion that the eyes are the window to the soul appears to have a parallel in the world of medicine. If not quite opening up the soul to scrutiny, doctors have long been aware that even the minutest of eye movements can indeed reveal many secrets of a person's state of mind.

Now researchers in Christchurch have developed a laser scanner to painlessly detect and record eye movement, allowing diagnosis of neurological disorders such as Parkinson's disease, multiple sclerosis and physiological problems affecting balance. Industrial Research Ltd's machine vision experts are helping to refine and improve the instrument's performance.

Richard Jones of Christchurch Hospital says the new device is proving very helpful in the diagnosis of these disorders.

"We can also learn a lot more about how the brain controls eye movements."

Existing systems for measuring eye movement have used devices such as special contact lenses and magnetic coils attached to the eye, often requiring a local anaesthetic.

Phil Bones and Bruce Wilson from Canterbury University originally had the idea that a vector scanning laser -- which scans in a line a little like the scanners which read barcodes at supermarkets -- could be much more effective and less invasive than existing methods.

The scanner they developed sweeps across the iris vertically, horizontally and in a circle around its perimeter 100 times every second. For the vertical and sideways movement the scanner measures the position of the edge of the iris. To measure the eye's rotation -- a movement few people are even aware of -- the laser records the pattern of markings on the iris around the perimeter then compares this with the pattern on later sweeps.

Jones says few of the alternative systems can measure the three types of movement at the same time.

Measuring the rotatory movement of the eye has been very difficult up until now. The new computer-aided instrument ability to reliably record and analyse this movement allows valuable insights into cerebellar and inner-ear disease.

While still only in the development phase, the research done on patients to date has demonstrated that the new device performs very well. The prototype instrument, developed with the help of Lottery Grant's Board and Canterbury Medical Research funding, now requires commercial funding to develop it to the stage where it can be sold to hospitals worldwide.