Device that measures metabolic stress may give early warning for eye disease

Washington, February 23 : University of Michigan researchers say that they have successfully tested a novel metabolic imaging instrument for its effectiveness in detecting eye disease at a very early stage.

A researcher duo from the U-M Kellogg Eye Center-Dr. Victor M. Elner and Dr. Howard R. Petty-says that such a device may prove vision-saving, as many severe eye diseases do not exhibit early warning signals before they begin to diminish vision.

The researchers have revealed that the new instrument makes for a non-invasive test, which takes less than six minutes to administer to a patient.

In a study, they used the new instrument to measure the degree to which a subtle visual condition affected six women.

The study participants had recently been diagnosed with pseudotumor cerebri (PTC), a condition that mimics a brain tumour, and often causes increased pressure on the optic nerve that can lead to vision loss.

The researchers found that the new instrument to be superior in evaluating vision-visual fields, visual acuity, and pupillary light response-than several standard tests that are used for the same purpose.

According to reports, the study grew out of Petty and Elner's observation that metabolic stress at the onset of disease causes certain proteins to become fluorescent.

With a view to measure the intensity of the flavoprotein autofluorescence (FA), the researchers designed a unique imaging system. They equipped it with state-of-the art cameras, filters, and electronic switching as well as customized imaging software and a computer interface.

Explaining as to why FA data is a good predictor of disease, Petty said: "Autofluorescence occurs when retinal cells begin to die, often the first event in diseases like glaucoma and diabetic retinopathy. Cell death can be observed microscopically, but not as yet though any current imaging methods. We believe this study is a big step forward toward creating a diagnostic tool that can characterize disease long before symptoms or visible signs appear."

During the study, the researchers observed that the participants had higher FA values in the eye that was more severely affected.

They said that while FA values averaged 60 per cent greater in the more affected eye of the women participants, the control group had no significant difference in FA values between their healthy eyes.

They also found that FA data more accurately described the different degree of disease in each eye for a given patient, as compared to the standard vision tests.

"Early treatment for eye disease is so important, and this study suggests that FA activity is a very good indicator of eye disease. Cardiologists have long used blood pressure testing to head off heart disease. We believe that FA testing will likewise be a helpful diagnostic tool for eye doctors looking to prevent blindness," said Elner, an ophthalmologist and a pathologist.

Elner and Petty, who have patented the device through the U-M Office of Technology Transfer, are investigating its use as a screening device in diabetes and other major eye diseases.

Their study has been reported in the Archives of Ophthalmology.

ANI