Photographs for Diagnosis

Retinal snapshots could help identify with precision people at high risk of suffering a stroke, say US researchers. They say their technique is cheap enough to be used by opticians and GPs to mass-screen patients.Strokes are caused by brain cell death due to bleeding from damaged blood vessels. Over 500,000 people suffer strokes every year in the Asia alone. Retinal scans are simple, non-invasive procedures (Photo: National Eye Institute, National Institutes of Health) Drugs that are effective at preventing stroke in high-risk patients are available, so doctors are keen to identify people with changes to their network of blood vessels - their vascular system - that make them more likely to suffer a stroke.

Previous research has shown that people with a narrowing of certain brain blood vessels are at a higher risk of stroke. A team led by Tien Yin Wong at the University of Wisconsin in Madison reasoned that a narrowing of similar blood vessels in the retina should be a good indicator of these changes. "We assume the changes in the vessels on the retina are the same as any in the brain, " says researcher Larry Hubbard.

The team photographed the retinas of 10 358 people and monitored their health for three years. They found that people with 'blots' or narrowing of tiny blood vessels on the retina were two and a half times more likely to suffer a stroke during the study.

Ann Elsner who is organising a conference on the retina at the Schepens Eye Institute in Boston says the study shows the value of looking carefully at the eye. "The retina is a window to the vascular system," she says.

Yin Wong looked at vascular changes on the micrometer scale - far too small to be seen with the naked eye. He developed a computer program to measure and compare the ratio between the size of arterial blood vessels, taking blood to the eye, and venuolar blood vessels, taking it back to the heart.