Camera can spot diabetes early
David L. Shenkenberg
Diabetes is a disease associated with high levels of the sugar glucose in the blood. It affects 24 million people in the US alone, and some 57 million more have prediabetes. The excess sugar hurts all the organs of the body and can even lead to death, but patients often do not know that they have the disease until complications become serious.
An ophthalmic imaging system developed by researchers at the University of Michigan, Ann Arbor, could detect diabetes before symptoms otherwise become apparent, and even before detection by the standard procedure — the glucose tolerance test — is possible.
A new ophthalmic camera takes a fluorescence picture of the eye and can detect diabetes and possibly other maladies of the eye.
The new system not only is potentially more sensitive but also has another advantage. The researchers said that patients often avoid the standard procedure, and it’s no wonder why they do. A patient undergoing the test must go without food, must drink a glucose solution and then must have his or her blood drawn more than once over a period of a few hours. In contrast, the new imaging system simply takes a fluorescence photograph of each eye in about 5 minutes.
It uses two Photometrics back-illuminated electron-multiplying CCD cameras equipped with a commonly used ophthalmic imaging system called a fundus camera. The researchers put Omega Optical filters on the CCD camera lenses. One CCD camera flashed the eyes through a blue filter (467 nm), and the other captured the images through a green filter (535 nm).
The blue camera flash stimulated flavoprotein in the eye to autofluoresce, and the other camera’s filter allowed it to detect the green autofluorescence. During stressful conditions, flavoprotein becomes oxidized, making it capable of autofluorescence.
For this reason, the scientists noted that flavoprotein autofluorescence could indicate other conditions besides diabetes that might induce stress, so patients who test positive with the imaging system would undergo the oral glucose tolerance test to determine if they in fact have the disease.
Although the imaging system would not replace the standard procedure, it would serve as a hassle-free early screening tool. It bears mentioning that the deterioration of the eyes because of diabetes, a condition called diabetic retinopathy, is the leading cause of blindness in working-age adults in the US.
The clinicians used the imaging system on 21 people with diabetes and compared the results with healthy people of the same age. They found that the flavoprotein autofluorescence indicated that a patient had diabetes and that the autofluorescence increased with age, although it did not correlate with the severity or the duration of the disease.
The doctors said that, because the level of autofluorescence reflects ongoing tissue damage, it might promote healthy habits among patients with diabetes — more so than blood glucose levels, which just indicate that the patient has the disease.
Dr. Victor M. Elner and Howard Petty, two principal investigators involved with the work, have founded a spin-off company called OcuSciences Inc. to commercialize the technology.
Archives of Ophthalmology, July 2008, pp. 934-938.
MORE FROM PHOTONICS MEDIA