Visionary technique

A device that detects the early signs of skin cancer could soon be used to help prevent blindness.

Researchers at Birmingham University are investigating the use of image analysis technology that can diagnose skin cancers to detect diseases of the retina often caused by diabetes, which can lead to blindness if not treated quickly.

Diabetic retinopathy is the largest single cause of blindness among people of working age in the UK, while even higher numbers suffer impaired vision as a result of the condition, said Dr. Ela Claridge, senior lecturer at Birmingham University’s school of computer science.

In the early stages of diabetes blood vessels in the eye become fragile, making them prone to leakage and haemorrhage. But these early signs are extremely difficult to spot, as they are masked by the dark colouration of melanin in the eye.

The SIAscope, initially developed from the university’s research by Cambridge-based AstronClinica, produces a detailed map of the back of the eye, allowing doctors to make an accurate diagnosis at an early stage of the disease’s development.

The earlier the problem is detected, the more effective treatments to prevent blindness are likely to be, said Claridge. ‘With diabetes, if you attack a problem very early there are treatments. Patients could be given insulin, or have laser treatment to stop the haemorrhaging.’

Like skin, the tissue around the retina at the back of the eye is composed of blood, melanin and collagen, each of which has a different colour. Light interacts differently with each of these colours, and the Siascope can measure the amount of each frequency of light absorbed, scattered and reflected by the tissue. A mathematical model then constructs a map, showing the amount of each component in the tissue at every point.

This map can be compared to the image of a healthy retina, enabling a doctor to detect early signs of disease, said Claridge. ‘In normal human tissue, the colours all fit a particular mathematical equation, but if a person has a potential cancer (or diabetic retinopathy) it does not.’

The existing technique for detecting diseases of the retina, angiography, is invasive and uncomfortable, involving the injection of a substance into the eye, which fluoresces when light is shone on it. In contrast, the Siascope simply involves the use of a special camera taking an image of the patient’s eye.

The research project is expected to last for two years, and if successful will be followed by clinical trials to test the technique on patients’ eyes. While the project is purely concerned with diabetes, the technique could eventually be used to detect other diseases, such as melanoma of the eye caused by exposure to UV light, said Claridge.