January 18, 2002

UM Kellogg Eye Center encourages screening for early detection of glaucoma

Ann Arbor—Because glaucoma appears gradually, without warning symptoms, about half of those who have the disease aren’t aware of it until considerable damage has already occurred. Early detection is especially important for those at highest risk for the disease--African Americans over the age of 40, all people over the age of 60, and those with a family history of glaucoma. About three million people in the United States have glaucoma, and as many as 120,000 have lost their vision to the disease.

"Glaucoma was once thought of as a single disease, but it is actually a group of diseases in which gradual damage to the optic nerve can cause blindness," explains Paul R. Lichter, M.D., Director of the Kellogg Eye Center and chair of the department of ophthalmology and visual sciences.

The most common form of the disease, chronic open angle glaucoma, occurs when fluid in the eye does not drain properly. The eye’s natural drainage channel, the trabecular meshwork, can become less efficient with age, resulting in buildup of fluid and increased intraocular pressure. The pressure damages the optic nerve and, if untreated, can cause irreversible blindness. If this form of glaucoma is not detected early on, the first sign is likely to be decreased peripheral vision, creating the sensation of tunnel vision.

While many people associate increased eye pressure with glaucoma, this factor alone can be misleading, explains Dr. Lichter. "As many as half the people with glaucoma have ‘normal’ eye pressure," he says. Physicians must perform a number of tests--measuring eye and blood pressure plus a comprehensive eye exam through dilated pupils--to arrive at an accurate diagnosis.

Because there is currently no cure for glaucoma, physicians rely on a variety of treatment strategies to stop progression of the disease. Current options include eye drops, oral medication, and laser or conventional surgery to correct the blocked channels.

Advances in Glaucoma Research
Kellogg physicians and scientists are looking for improved treatments and, one day, a cure for the various forms of glaucoma. Current research efforts include clinical trials to compare various treatment options, studies to identify glaucoma genes and other related genes that impact on glaucoma, and—a little further down the road—development of individualized treatments matched to a person’s genetic makeup.

Ophthalmologists have long debated whether glaucoma surgery or medication is the best initial treatment for patients. Currently, Dr. Lichter directs a multi-center study at 14 clinics across the nation to determine which approach is more effective for patients with glaucoma. The preliminary findings, released at the American Academy of Ophthalmology’s annual meeting in November 2001, suggest that medications and surgery appear to be equally effective initial treatments for newly diagnosed open-angle glaucoma. The research team will extend the initial five-year study since longer term follow-up is important for a chronic disease like glaucoma.

Sayoko Moroi, M.D., Ph.D., sees great potential in pharmacogentics and glaucoma medical therapy. Pharmacogenetics examines how differences in an individual’s genetic makeup affect how he or she may respond to a particular drug. Dr. Moroi also stresses the importance of looking at multiple approaches to understand glaucoma treatment; she continues to study how drugs impact their targets along cellular pathways. "We now understand the genetic basis for why certain individuals vary profoundly in response to drugs. For certain drug classes disposed of by the liver, frequent variations in liver enzymes determine how quickly or slowly the drug is metabolized," says Dr. Moroi. "We are beginning to apply the same principles to treating eye disease." Dr. Moroi’s goal is to determine whether there is a genetic basis to understand who has a "good" versus "poor" response to a particular glaucoma medication, and also who may develop side effects. She explains that if there is a genetic basis for understanding response to glaucoma medications, then perhaps a diagnostic gene chip may be developed to each patient’s genetic profile so that physicians can tailor treatment accordingly.

Kellogg research scientist Julia Richards, Ph.D., works toward identifying the genes associated with glaucoma, but notes that the process is complicated because glaucoma is not a single disease. While that search continues, she is also looking at changes in gene expression that take place as the disease develops. "We know that glaucoma can start with a build-up of pressure inside of the eye and that the pressure results in damage to the optic nerve," she explains. Dr. Richards wants to know what happens midway between the initiator point and the end point. "We are just beginning to figure out some of the events that can start the increase in pressure," she says. "But we are finding commonalties in gene expression that could one day help us develop therapies that will treat the disease."

The U-M Kellogg Eye Center is a nationally recognized vision care and research center. As part of the University of Michigan Health System, Kellogg provides medical and surgical eye care, including laser eye surgery; professional and public education; and performs advanced ophthalmic research. Kellogg also serves as a regional referral resource, providing specialty vision care that may not be available in other communities.

For more information about glaucoma call the U-M Kellogg Eye Center at 734-763-1415

Contact: Betsy Nisbet, 734.647.5586, bsnisbet@umich.edu.