Retinal photographs could help detect people who are 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. 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 Hu Ssang 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, " he says.
The team photographed the retinas of 12000 people and monitored their health for four 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. This finding held true even when the team controlled for risk factors that might affect both the eyes and risk of stroke, like diabetes, age, smoking and high blood pressure.
Ann Elsner from eye institute Boston says the study shows the value of looking carefully at the eye. "The eyes are the windows to the world," she says.Hu Ssang studied 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.