AIthough glaucoma is primarily a disease of the aging, it may occur at any age or at birth. According to the NIH's National Eye Institute, glaucoma is a major health problem and the leading cause of blindness in African Americans. Approximately 3 million Americans have glaucoma. Alarmingly, at least half of all those who have glaucoma are unaware of their condition. Current treatment for glaucoma involves medications and/or surgery to lower the eye pressure. Although effective in slowing the progress of the disease in most patients, this approach has not prevented glaucoma from ranking as one of the two leading causes of blindness in the U.S.

GLAUCOMA

&THE BRAIN

 

Led by Robert N. Weinreb, M.D., a team of scientists at UCSD's Glaucoma Center recently reported that glaucoma is not a disease restricted only to the eye. Their study, "Loss of LGN Neurons in Glaucoma," appeared in the March 2000 issue of Archives of Ophthalmology.

Glaucoma is one of the two leading causes of blindness in the United States. It affects at least 3 million Americans and more than 66 million individuals worldwide. Loss of optic nerve fibers in glaucoma can lead to blindness if not adequately treated. Though commonly misunderstood as a disease of "increased eye pressure" the hallmark of glaucoma is the optic nerve fiber loss, regardless of the pressure.

Visual information originates in the eye, then is sent as an electrical signal to the brain. On its way to the brain, it passes through the lateral geniculate nucleus, a relay station that decodes visual information prior to it being sent to the visual cortex of the brain. Ninety percent of the optic nerve fibers from the eye terminate in the lateral geniculate nucleus. The visual cortex detects the electrical signals, processes them, and provides us with our sense of sight.

Dr. Weinreb's group, including lead author Yeni Yucel, M.D., Ph.D. (a neuropathologist and UCSD Postdoctoral Glaucoma Fellow at the time, presently the Director of Ophthalmic Pathology at the University of Toronto ), found in a primate model that there was extensive loss of nerve cells in the lateral geniculate nucleus with progressive glaucoma, a process known as transneuronal degeneration. According to Dr. Weinreb, by studying changes in the brainstem we may better understand what causes vision loss in glaucoma. This information could be critical in helping researchers determine how to prevent vision loss in patients with known glaucoma or at risk for delaying it.

Hope for patients with glaucoma lies in medications that can directly prevent the death of optic nerve cells, rescue sick nerve cells, and protect healthy ones from dying. This new approach, called "neuroprotection:' seeks to prevent initial and progressive damage to the optic nerve by protecting it from clinical, biological, and environmental attacks. Dr. Weinreb believes the future of neuroprotection for saving and restoring the vision in glaucoma is excellent. Nevertheless, he cautioned that it may require several years to demonstrate this in clinical testing, which will be conducted around the world.

"Until these studies are concluded," Dr. Weinreb states, "Early detection and treatment with eye pressure-lowering medication or surgery remain the only effective treatment of glaucoma."

FIVE KEYS TO UNDERSTANDING GLAUCOMA
by Dr. Weinreb

1. The optic nerve is a "cable" that transmits the visual message from the eye to the brain.

2. In glaucoma, the optic nerve fibers are damaged and then die.

3. Examination of the optic nerve allows your eye doctor to diagnose glaucoma.

4. Damaged nerve fibers lead to loss of vision.

5. You may not be aware of any vision problems.