Saving Eyesight: Developing A Test To Detect Glaucoma At Its Earliest Stages

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Saving Eyesight: Developing A Test To Detect Glaucoma At Its Earliest Stages

http://www.medicalnewstoday.com/articles/183509.php

Scientists are reporting progress toward a test that could revolutionize the

diagnosis of glaucoma - the second leading cause of vision loss and blindness

worldwide - by detecting the disease years earlier than usually happens at

present. They reported the findings at the 239th National Meeting of the

American Chemical Society (ACS).

" We are confident that we're moving toward a breakthrough that will allow us to

detect glaucoma at its earliest stage, " said Chenxu Yu, Ph.D., who headed the

study. " We hope it will benefit millions of glaucoma patients and individuals at

risk for this devastating eye disease worldwide. "

Glaucoma is a group of eye disorders that can damage the optic nerve, which

carries visual information from the eye to the brain. It usually occurs when

fluid pressure inside the eye slowly increases over time. The fluid presses on

the optic nerve and damages it. Glaucoma affects about 70 million people

worldwide, including about 2 million in the United States. It damages vision by

stealth, with no obvious warning symptoms that would send patients to a doctor.

There is no cure, and glaucoma causes irreversible loss of vision.

Doctors now use two main techniques to detect the disease. One test is

tonometry, which measures eye pressure by gently touching a special instrument

to the outer surface of the eye. The other is ophthalmoscopy, in which an eye

specialist uses an instrument called an ophthalmoscope to look directly through

the pupil of the eye at the optic nerve. The nerve's color and appearance can

indicate the presence of damage from glaucoma.

" All too often, these tests detect glaucoma after the disease has been silently

causing damage to the optic nerve, " Yu explained. " Years may pass between the

first biological change associated with glaucoma inside the eye and diagnosis.

We need ways of diagnosing glaucoma earlier, before permanent damage has

occurred, so that patients can begin taking medication to control it. "

In their ACS report, Yu and colleagues described development and early testing

of a potential new early diagnostic method. It gives a mainstay tool in

chemistry labs - Raman spectroscopy - a potential new life in medicine. The

technique as used in chemistry and other laboratories involves focusing a beam

of infrared laser light - invisible to the human eye - into a test sample to get

information about the sample's composition. Yu's method uses Raman spectroscopy

to shine laser light through the pupil of the eye. Optic nerve cells (retinal

ganglion cells) inside the eye scatter the light, producing a rainbow-like

" spectrum " or pattern revealing the chemical composition of the cells.

Scientists can then use that snapshot to identify biochemical changes in retinal

cells that announce the presence of glaucoma.

Efforts are underway to use Raman spectroscopy - named for an Indian scientist

who won the Nobel Prize for developing it - elsewhere in medicine (i.e., cancer

diagnosis). But Yu described this research as among the first attempts to apply

the Raman technology to diagnosis of glaucoma.

Yu and his colleague, Dr. Sinisa Grozdanic, a glaucoma researcher and Director

of Animal Research for the Iowa City Veterans Administration Center for

Treatment and Prevention of Vision Loss (VA CPTVL), are pleased with results of

animal retinal tissue testing from glaucomatous dogs, in which the technique

detected glaucomatous changes with 90 percent accuracy, the scientists say.

" " This is a very promising technique, " said Yu, an assistant professor at Iowa

State University in Ames. " We are very excited about the results so far and look

forward to additional studies. "

The scientists look forward to potential clinical trials in humans. If animal

studies go well, and show good efficacy and safety of methodology, the technique

could be ready to be used in eye doctor's office within five years, they

estimate. The test likely will take about 30 minutes, longer than existing

glaucoma tests, but may benefit patients with more accurate diagnosis of

disease, Yu said.

The research carries personal meaning for Yu. Doctors have diagnosed him as a

being at high-risk for glaucoma. Yu's collaborators in this study also include

Qi Wang, a doctoral student at the university; Hamouche, M.D., a

glaucoma specialist, at McFarland Clinic in Ames, Iowa; and Drs. Harper

and Helga Kecova who are research scientists at the Iowa City VACPTVL. The Iowa

State University and Veterans Administration funded the study.