Victor M. Elner and Howard R. Petty, two scientists of the University of Michigan Kellogg Eye Center have invented a new vision screening instrument that could give doctors and patients an early warning of diabetes and vision complications related to the disease. The device captures images of the eye to detect metabolic stress and tissue damage that take place before the first symptoms of disease are evident.

For people with diabetes, diagnosed or not, the new device could offer considerable advantages over blood glucose testing, the "gold standard" for diabetes detection. The new instrument takes a specialized photograph of the eye. The process is non-invasive, and takes about five minutes to test both eyes. If further testing confirms the results to date, the device may be useful for screening people who are at risk of diabetes but haven't been diagnosed.

Elner said that the objective of their study was to determine whether they could detect abnormal metabolism in the retina of patients who might otherwise remain undiagnosed based on just clinical tests. Metabolic stress, and therefore disease, can be detected by measuring the intensity of cellular fluorescence in retinal tissue. In an earlier research, Petty and Elner showed that high levels of flavoprotein autofluorescence (FA) act as a reliable indicator of eye disease.

In their new study, they measured the FA levels of 21 people who had diabetes and compared the results to age-matched healthy controls. They 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 unaffected by the severity or duration of disease and were elevated for diabetics in each age group: 30 to 39 years, 40 to 49 years, and 50 to 59 years.

Twelve participants in the study were known to have diabetic retinopathy, a disease in which blood vessels in the eye are damaged. Those 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. Elner said the abnormal readings indicated that it may be possible to use this method to monitor the severity of the disease.

Petty said that hyperglycemia, i.e., high blood sugar, is known to cause cell death in diabetic tissue soon after the onset of disease but before symptoms can be detected clinically. "Rise in FA activity is the earliest indicator that cell death has taken place and tissue is beginning to break down. FA serves as a 'spectral-biomarker' for metabolism gone awry, and we can use the results to detect and monitor disease," said he.

Petty also said that unlike glucose monitoring, elevation of FA levels reflects ongoing tissue damage. That knowledge, according to him, could motivate patients to intensify their efforts to manage diabetes.

Both Elner and Petty are unanimous that the new instrument has great potential as a tool for diabetes screening and management. They have filed for patents and have formed a company, OcuSciences, Inc., to commercialize the metabolic imaging device.