Many diseases that afflict us in later life are due to changes in our blood vessels. Diabetes, high blood pressure, stroke and heart attacks all have their origins in damaged or blocked arteries, and collectively they create an enormous burden of disease.

It can be highly beneficial to detect the disease early - and, suggests clinical pharmacologist Dr Simon Thom of Imperial College, London, the maze of blood vessels on the surface of the retina might provide a new way to identify people at risk.

In the late 1980s Ron and Barbara Klein, professors of ophthalmology at the University of Wisconsin, carried out a large population survey in Beaver Dam, a small town near Chicago in the US midwest. Part of the study involved taking retinal photographs of nearly 5000 people. These men and women, aged between 43 and 84, were then tracked to see who developed heart disease or suffered strokes.

Dr Thom and his team - engineers Anil Bharath and Nick Witt and professors Alun Hughes, Kim Parker and Nish Chaturvedi - are spending six months scrutinising the pictures to see if distinctive changes are apparent in those who subsequently suffered ill health.

"Photographs taken through the pupil reveal the geometry of the retinal blood vessels," explains Dr Thom. "The pattern of these blood vessels is influenced by the layer of cells that line their inner surface - the endothelium. We know that changes in these geometric patterns occur at an early stage in several cardiovascular disease processes. Hopefully, we will be able to use this technique to identify potential problems in advance of catastrophe."

Precise and early predictive approaches to prevent cardiovascular disease are as yet elusive. "At the moment we wait until a patient's sugar levels are high or blood pressure has gone up before we realise something serious, such as a heart attack or stroke, might be on the way."

But early intervention through lifestyle changes or drugs could prevent that event ever happening.

The retinal scanning technique looks promising, and the analysis of the US samples, funded by a Wellcome Trust project grant, will show clearly whether it has practical application. One difficulty, Dr Thom acknowledges, is the sheer amount of work a screening programme would entail. "For example, diabetic retinal disease is the commonest cause of adult retinal blindness; if we screen for this problem, as proposed in the National Service Framework, there would be the daunting task of checking millions of images. It would take an army of ophthalmologists years to analyse them."

The answer, he suggests, is automation: "If there is a computer system programmed to do the work it would reduce the amount of time dramatically and accrue a massive economic saving."

He also has an innovative suggestion for how a nationwide screening service might work - by tying it in with potential plans to introduce an identity card. The government has toyed with the idea of introducing some form of official identification. "From our point of view it would be fantastic if it could be done with a retinal image, which is unique to individuals," says Dr Thom. "While carrying out this procedure, checks could be made from the image which could reveal possible health risks. So you are solving two problems with one initiative."

That may be a long shot, but other approaches are possible: "Retinal imaging is very simple - it takes a few minutes. We still need the final evidence, of course, but who knows - we might soon have a situation where you can just pop into a local health centre to have this done and the results could be life-changing for many people."

External links

• Dr Simon Thom at Imperial College, London: Research interests
  University of Wisconsin: Affiliation of Professors Ron and Barbara Klein in the late 80s