New spectral imaging technique will help diagnosis of glaucoma, diabetic retinopathy and age related macula degeneration

Sep 8 2004

A new way of taking pictures of the retina could give medics a powerful new tool in diagnosing and monitoring the most prevalent diseases of the eye - glaucoma, diabetic retinopathy, and age related macula degeneration.

The technique was revealed today at the Institute of Physics conference Photon 04 in Glasgow.

By 2020 there will be 200 million visually-impaired people worldwide but 80% of these cases are preventable or treatable. For this to happen, screening and early detection are crucial. Sonny Ramachandran, from Heriot Watt University in Edinburgh, outlined a new technique that uses spectral imaging, a non-invasive and safe method of taking pictures of the retina, to study the blood vessels of the eye and reveal the presence or progression of any disease.

They modified a standard ophthalmoscope, adding a liquid crystal tuneable filter, which allowed them to take images of the retina at a series of specific wavelengths. The images are captured by a sophisticated digital camera - a cooled, low noise CCD camera. Image processing corrects for the movements of the eye while the pictures are being taken, and a large set of images are combined in a "data cube" to improve the quality of the resolution.

Spectral imaging is unique because it allows scientists to take images taken at specific wavelengths. Crucially, wavelengths between 580nm and 600nm reveal the oxygenation state of the blood vessels in the eye, telling doctors which areas are healthy and which might be diseased.

Dr. Andrew Harvey, one of the supervisors of the project said: "So far, we've used this technique to take images of the retina in healthy subjects, patients with diabetic retinopathy and patients with glaucoma and in all cases it seems that our images are extremely successful in helping doctors detect and chart the condition. We're now at the stage of trialling this much more rigorously in a clinical setting but are very hopeful that this will be a promising new tool that will help doctors screen and monitor the major diseases of the eye."

"Some of the existing screening techniques, such as the Fluorescein Angiogram for diabetic patients, can be painful and in some cases dangerous with patients dying during treatment. This new technique is safe, quick and simple, and totally non-invasive so going for regular check-ups every four months won't be so daunting for patients".

The research team is composed of Sonny Ramachandran and colleagues David Fletcher-Holmes, Nick Taylor, Andrew McNaught & Andrew Harvey, from the School of Engineering & Physical Sciences, Heriot Watt University, Edinburgh, UK, and is working with Eye Unit at Cheltenham General Hospital.