It’s often said that about 50 percent of patients with glaucoma don’t know they have it. But when you look at most prevalence studies, the percentage is even higher—about 80 percent of patients may fall into this category. So there’s an enormous population of people who are at risk of losing vision from “the sneak thief of sight,” who may not take action until they’ve already lost a significant portion of their vision.
Screening in a traditional sense means identifying people who are at high risk of having a specific disease; it normally involves one or two tests. It’s different from a diagnostic exam where you try to determine whether or not the patient has the disease. This distinction is important because, in glaucoma, for example, we don’t have enough manpower to do a complete examination of everybody in the United States who’s at risk. But it might be possible to identify those at higher risk of developing glaucoma through screening. Then, individuals with suspicious screening results can have a gold-standard exam to confirm or refute the screening results.
It’s not hard to see the potential benefits of such an endeavor. One, of course, is that you do find individuals with glaucoma who clearly would not have gone to a clinic for an eye exam. Many people are far more willing to be tested with an FDT perimeter at a health fair than to visit a doctor’s office. And if you find a sign of trouble, that gets these people into the health-care system.
Furthermore, there are benefits beyond simply detecting disease. Screening also educates people about the signs and symptoms of glaucoma. Even if passers-by don’t participate in the screening, they see the sign that says that glaucoma can occur in family members of those who have the disease. It starts a discussion between the person and his family; then members of the family go and have an eye exam. Simply educating people about glaucoma is extremely important.
The educational value of community screenings is difficult to measure—but knowledge is a powerful weapon against a silent, asymptomatic disease that can rob you of your vision. Sadly, every week a patient comes into our clinic who has had undiagnosed glaucoma for a long time, without any treatment. Earlier treatment could have allowed him to retain a significant part of his vision.