Eye Test Detects Early Stages of Diabetes

By capturing a snapshot of the eye, scientists in Michigan say that they can pick up telltale signs of metabolic stress in the retina caused by diabetes. They say that the new imaging technology may offer a quick, noninvasive way of detecting the disease early and monitoring its progress.

"With just a minute in an optometrist's office, you might be able to detect metabolic stress in the eye, refer the patient to an endocrinologist, and get a diagnosis," says Howard Petty, a biophysicist and imaging expert at the University of Michigan's Kellogg Eye Center .

The study focused on patients with diabetes, but Petty says that the screening technology should be able to identify people with prediabetes--a condition in which blood glucose levels are higher than normal and that often progresses to full-blown diabetes. The researchers are beginning clinical trials this fall, using the system on diabetics and prediabetics.

Petty, and other colleagues at the University of Michigan, used a sophisticated camera system coupled with customized imaging software to detect fluorescence given off by oxidized proteins in dying cells in the retina. The 21 diabetics in their study had elevated levels of autofluorescence from retinal flavoprotein, compared with healthy age-matched control subjects. Diabetics that had --damage to the retinal tissue that can causes blindness--had even higher levels of fluorescence than diabetics without the condition.

Even if the eye test proves effective in clinical trials, it's unlikely to replace blood sugar screening, the test most commonly used to detect diabetes. However, it may provide a useful early-warning tool. Petty hopes to make the eye imaging system inexpensive enough that it could be used by optometrists, not just ophthalmologists, to identify people who may have prediabetes.

Eye tests could be used to monitor diabetic patients,� and assess the effects of drug treatments and lifestyle changes. Diabetics can lose "a substantial fraction--up to 50 percent--of their retinal cells" before they're aware of vision problems, Petty says, because the brain adjusts to the input from the eyes--up to a certain point. "Once you're beyond that threshold, right now . . . you really can't get [vision] back," he adds.

Petty and his colleagues are now having a much smaller version of their first eye imaging system built. It will be easier to use, and unlike the current version, it won't require a patient's eyes to be dilated. Petty and Elner have filed for patents and formed a company, OcuSciences, to commercialize the technology.

Source: Diabetes In Control: Archives of Ophthalmology, July 2008