USPSTF Finds Evidence Is Insufficient to Make POAG Screening Recommendation

The U.S. Preventive Services Task Force (USPSTF) is proposing a draft recommendation statement indicating that current evidence is insufficient to assess the balance of benefits and harms of screening for primary open-angle glaucoma (POAG) in adults. The recommendation applies only to adults without vision symptoms who are seen in a primary care setting.

According to the draft statement, open-angle glaucoma affects approximately 2.5 million Americans and is a leading cause of impaired visual function and blindness. Approximately 62 percent of Medicare patients received screening for glaucoma in 2009.

Although the task force found no studies that directly evaluated the benefits of screening, it did find convincing evidence that treatment of adults with increased intraocular pressure (IOP) and early glaucoma "reduces the number of persons who develop small, clinically unnoticeable visual field defects, and that early treatment of early asymptomatic POAG decreases the number of patients whose visual field defects worsen."

On the other hand, the USPSTF did not find sufficient evidence to determine whether screening for or treatment of increased IOP or early asymptomatic POAG decreases the number of people who will develop impairments in vision-related function or quality of life.

Furthermore, the task force found no direct evidence on the harms of screening, although it did find convincing evidence that treatment of increased IOP and early POAG results in a number of harms, including local eye irritation from medications and a risk of complications from surgery. "There is also a risk for overdiagnosis and overtreatment, as there is some evidence that most individuals with early increased IOP or POAG have an indolent long-term course, yet still receive treatment," said task force members.

Finally, the USPSTF found inadequate evidence on the accuracy of screening for POAG in adults. "The evidence is limited by the lack of an established gold standard against which individual screening tests can be compared," the task force said in its recommendation statement.

Overall, the task force concluded that the evidence of effectiveness of glaucoma screening on clinical outcomes is lacking; therefore, the balance of benefits and harms could not be determined.

In the evidence review USPSTF members used in formulating their recommendation statement, researchers said their ability to synthesize evidence was limited by several factors, including that

The researchers noted that their review supports the role of medical, surgical and laser treatments in decreasing IOP in patients with glaucoma and said they were able to draw some conclusions about the relative effectiveness of particular treatment options. But head-to-head treatment comparisons were lacking, they added.

"Although evidence suggests that these treatments prevent progressive visual field loss and optic nerve damage, we did not identify high-level evidence comparing those treatments with one another," the researchers wrote. "We also failed to find evidence linking treatment of any kind to patient-reported outcomes or visual impairment, which should be considered the outcomes of most interest."

The AAFP's own 2005 recommendation also cites a lack of evidence to recommend for or against screening adults for glaucoma.

The draft recommendation statement is available for comment until March 18.