Glaucoma expert urges a new look at screening

Fort Lauderdale, FL-More aggressive glaucoma screening methods and a better understanding of disease progression as well as its incidence and prevalence among various population groups are essential to lessening the devastating impact of this disease worldwide, said Harry A. Quigley, MD, during the 2004 Friedenwald Award lecture at the Association for Research in Vision and Ophthalmology (ARVO) annual meeting.

The need for a better understanding of glaucoma is evident from a look at the status of the disease outside of the United States, Dr. Quigley said during a lecture entitled "Glaucoma: From Macrocosm to Microcosm."

Although individuals with glaucoma do have a higher average IOP than those who do not have glaucoma, selecting a particular number, such as 21 mm Hg, as a cutoff point will exclude a significant number of people who have glaucoma or are at risk of the disease, he added.

"Even though the risk of glaucoma is lower at lower pressures, there are still a lot of people with glaucoma with normal eye pressures," Dr. Quigley continued. "It's time for us to agree that the use of the words 'low-' and 'normal-tension glaucoma' is meaningless, and we ought to stop doing it until somebody can show that there's actually something called that."

He also suggested that one screening approach that has the potential to be highly effective is underutilized: looking at family members of known glaucoma patients. The risk of a parent or sibling having glaucoma is about 10 times higher than the population prevalence, meaning that there are an estimated 3.75 million at-risk family members in the United States alone. Of those, an estimated 158,000 actively have glaucoma.

"If we could induce 50% of those family members to come in and if we could detect glaucoma in the office at a rate of 95%, we could find 75,000 new, undiagnosed cases of glaucoma in this country this year," Dr. Quigley said. "Are we really chasing the families the way that we should in terms of behavior in our practices? I don't think so."

Other approaches, such as focusing on a segment of the community, can catch a number of cases of glaucoma but may not be cost effective, Dr. Quigley said. For example, a screening program in inner-city Baltimore found about 100 cases of glaucoma among 16,000 individuals examined, at a cost of $1,500 per case.

"If you have lots of money and you have lots of time, perhaps you'd want to do that, but we need to work on better methods for screening and identifying this disease," he added.

Examining the extent of glaucoma worldwide, Dr. Quigley called its impact "quite severe," describing it as the second leading cause of blindness, having caused vision loss in an estimated 8 million individuals. In addition, the rate of glaucoma-related blindness is 10 times as high in poor countries as in wealthy, urbanized, developed societies, and the risk of death is higher as well. "It's not just that you're blind, you're also more likely to die if you can't see in many parts of the world," he emphasized.

An estimated 50 million people worldwide are affected with glaucoma; two out of three have open-angle glaucoma, and the remainder have angle-closure glaucoma.