Screening middle-aged African Americans for glaucoma may prevent some from losing their vision, but the benefits are modest and costly, suggests a new study.

About two percent of Americans over age 40 are affected by glaucoma, which is caused by too much pressure in the eye, but one of the study’s authors says it is a bigger threat to certain groups - particularly African Americans.

My dad, who is a coauthor on the paper, actually has glaucoma. He was diagnosed late and has some visual impairment from it… It’s been a gradual process of different treatments and gradually worsening condition,” said Dr. Joseph Ladapo, the study’s lead author and an assistant professor at the New York University School of Medicine.

The researchers wanted to know whether annual glaucoma screenings as part of a routine eye exam would stave off vision impairment or loss in some people.

We thought (African Americans) would get hit the worst. So, if we can’t show a benefit in this population, it’s unlikely that we’ll be able to show benefits in other populations,” Ladapo told Reuters Health.

Instead of conducting a clinical trial, Ladapo and his colleagues created a computer simulation using data on African Americans between 50 and 59 years old in the Eye Diseases Prevalence Research Group and the Baltimore Eye Study.

Based on their calculations, the rate of undiagnosed glaucoma in African Americans would drop from 50 percent to 27 percent if regular screenings were adopted nationwide. However, the benefits of preventing vision loss or blindness were much more modest.

The proportion of African Americans blinded by glaucoma would go from 6.1 percent to 5.6 percent, and those with glaucoma-related vision impairment would fall from 4.6 percent to 4.4 percent.

While any reduction in glaucoma rates may prevent people from losing some or all of their vision, the researchers determined 875 people would have to be screened to prevent one person from losing some of their vision.

It’s just horrible when people develop visual impairment, but we didn’t find that the benefits were that great,” Ladapo told Reuters Health.

And at about $80 per screening, preventing that one person from losing some vision carries a price tag of over $70,000.

But, the researchers write in the Archives of Ophthalmology, they consider the number needed to be screened to be comparable to other tests.

Dr. Nathan Radcliffe, director of Glaucoma Service at NY-Presbyterian/Weill Cornell Medical Center, said he also thinks it’s important for people to be screened, because it’s the only way to diagnose glaucoma and the examination may help find other unrelated conditions.

The only way a patient is going to know if they have (glaucoma) is if they have someone look into their eye,” said Radcliffe, who was not involved in the study.

He recommended people over 40 years old and those with a family history of glaucoma-related vision loss should get a baseline exam to reference as they get older.

Doctors identify glaucoma by looking at the person’s optic nerve and by testing their field of vision.

Radcliffe said glaucoma is treatable with drops or surgery, but not once they’ve lost the main parts of their vision.”

Still, he added, There is a huge window where we can diagnose glaucoma.”

SOURCE: Archives of Ophthalmology, March 2012.

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Joseph A. Ladapo, MD, PhD; Steven M. Kymes, PhD; Jonathan A. Ladapo, PhD; Veronica C. Nwosu, PhD; Louis R. Pasquale, MD
Arch Ophthalmol. 2012;130(3):365-372. doi:10.1001/archopthalmol.2011.1224