In revamping Medicare, one of the first preventive practices President George W. Bush put under the national health care policy was glaucoma testing, beginning in 2002. After all, screening people at high risk of developing the chronic eye disease had been common practice for decades. Then, in 2005, a government-sponsored panel of experts found that it could not make any definitive recommendation about glaucoma screening. The surprising conclusion sparked a debate over the risks and benefits of screening for the disorder. Now new evidence, some researchers and policymakers say, tips the balance in favor of the benefits.

Glaucoma affects about three million people in the U.S. and is a leading cause of blindness. It occurs when fluid pressure inside the eyes rises, irreversibly damaging the optic nerve that carries visual information from the retina to the brain. Blind spots begin to form on the periphery of people’s vision and can progress to tunnel vision that, left untreated, can then narrow to blindness.

As many as half of those with glaucoma in the U.S. do not know that they have the disease, according to the National Eye Institute. “There are no symptoms or signs. The disease is essentially picked up through screening,” explains Rohit Varma, an ophthalmology professor at the University of Southern California. Such screening typically involves checking a patient’s peripheral vision, examining the retina and optic nerve for damage and measuring the fluid pressure in the patient’s eye. Testing is important because a loss of vision cannot be reversed. Prescription eyedrops or surgery, or both, however, can halt its progression.

The National Eye Institute and other government agencies, professional societies and consumer groups recommend regular glaucoma screening for people at high risk, such as individuals with a family history of the disease, African-Americans older than 40, and everyone older than 60, especially Latinos. But in 2005 the U.S. Preventive Services Task Force (USPSTF), a panel of primary and preventive care experts sponsored by the U.S. Department of Health and Human Services, evaluated the scientific literature regarding testing and “found insufficient evidence to recommend for or against screening adults for glaucoma.”

In reviewing 13 studies, the task force saw evidence that screening can detect increased fluid pressure and early glaucoma in adults and that timely treatment for fluid pressure reduces the number of people who lose their vision from the disease. But it did not find enough evidence to determine whether screening and early detection lead to improved quality of life for glaucoma patients. Moreover, the task force cited eye irritation from screening and an increased risk for developing cataracts after glaucoma treatment as associated risks. So the panel did not recommend for or against screening. The apparently neutral stance effectively states that “the benefits don’t outweigh the risks,” comments Dennis McBride, academic president of the Potomac Institute for Policy Studies, a nonprofit public policy research group.

Concerned that the report would affect insurance coverage for glaucoma screening, the Potomac Institute and the Glaucoma Foundation held a conference last October to discuss national guidelines for glaucoma testing and treatment. Researchers also presented evidence that directly addressed the USPSTF question about quality of life. One such investigation, which is part of the larger Los Angeles Latino Eye Study, measured the extent of patients’ tunnel vision and asked them to describe how their condition affected their routines. Those with tunnel vision had the greatest difficulties with driving and activities that relied on distance and peripheral vision, and they scored lowest on surveys of mental health and dependency, researchers reported. “We’ve shown quite well that even with very early vision field loss, people’s daily lives are affected,” says Varma, who leads the study.

When contacted for this story, the USPSTF declined to comment, citing confidentiality in its deliberations. But McBride hopes in light of the new data, the task force will reevaluate the evidence for glaucoma screening and treatment ahead of its scheduled review in 2010. In summing up our value of sight, he remarks: “Older people are more afraid to lose their vision than to lose their life.”