Friday, July 18, 2008

Watching The Eye for Signs of Diabetes Changes

Filed under: Medicine , Ophthalmology

University of Michigan researchers are trialing a new in-house device that detects retinal flavoprotein autofluorescence, a potential indicator of the presence of diabetes-induced retinal metabolic changes, such as early diabetic retinopathy.

Metabolic stress, and therefore disease, can be detected by measuring the intensity of cellular fluorescence in retinal tissue. In a previous study, Petty and Elner reported that high levels of flavoprotein autofluorescence (FA) act as a reliable indicator of eye disease. In their new study, Elner and Petty measured the FA levels of 21 individuals who had diabetes and compared the results to age-matched healthy controls. The Kellogg scientists found that FA activity was significantly higher for those with diabetes, regardless of severity, compared to those who did not have the disease. The results were not affected by disease severity or duration and were elevated for diabetics in each age group: 30 to 39 years, 40 to 49 years, and 50 to 59 years.

Twelve individuals in the study were known to have diabetic retinopathy, a disease in which blood vessels in the eye are damaged. The individuals with diabetic retinopathy in at least one eye had significantly greater FA activity than people with diabetes who do not have any visible eye disease.

“The abnormal readings indicated that it may be possible to use this method to monitor the severity of the disease,” says Elner.

Petty, a biophysicist and imaging expert, explains that hyperglycemia — or high blood sugar — is known to induce cell death in diabetic tissue soon after the onset of disease but before symptoms can be detected clinically.

“Increased FA activity is the earliest indicator that cell death has occurred and tissue is beginning to break down,” says Petty, professor of Ophthalmology and Visual Sciences, and professor of Microbiology and Immunology at the U-M Medical School. “FA serves as a ‘spectral-biomarker’ for metabolism gone awry, and we can use the results to detect and monitor disease.”

Petty also observes that unlike glucose monitoring, elevation of FA levels reflects ongoing tissue damage. That knowledge, he says, could motivate patients to intensify their efforts to manage the disease.

The Michigan researchers also note that elevated FA does not always mean that an individual has diabetes. “Because of the prevalence of diabetes in our population, individuals with abnormally high FA would be prompted to undergo glucose tolerance testing,” says Elner. “If the findings were negative for diabetes, we would look for other causes of ocular tissue dysfunction.”

Press release: 'Snapshots' of eyes could serve as early warning of diabetes

Abstract in Archives of Ophthalmology...

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