The challenges of identifying glaucoma progression
From advances in medical technology and testing to increased awareness among the public, eyecare professionals are better able to identify glaucoma before it starts wreaking havoc on a patient's vision. But when it comes to identifying glaucoma progression, things get a little murkier.
Over the years, the ability to diagnose glaucoma has improved dramatically. From advances in medical technology and testing to increased awareness among the public, eyecare professionals are better able to identify glaucoma before it starts wreaking havoc on a patient's vision. But when it comes to identifying glaucoma progression, things get a little murkier.
Damage due to glaucoma can occur over long periods of time, and the changes to a patient's condition can sometimes be subtle. The industry has embraced stereo photographs as the gold standard for identifying progression, but they're not without their faults, either.
"Stereo photographs are difficult to use for detecting progression," says Murray Fingeret, OD, FAAO, chief of the optometry section at the Department of Veterans Administration New York Harbor Health Care System's Brooklyn/St. Albans Campus. "There's often not clinical agreement among clinicians about who is getting worse."
He cites one paper from Johns Hopkins in which numerous glaucoma specialists were shown a series of stereo photographs of glaucoma patients and then asked which patients showed progression. The study found "slight to fair" agreement among the doctors.
"In other words you could flip a coin and do better," he says. "And this is with stereo photographs, the so-called gold standard."
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OCT is doing a better job
Dr. Fingeret says optical coherence tomography (OCT) appears to be doing a better job.
"The ability to see structural change with the devices removes subjectivity,” he says. “These are reproducible devices improving resolution, reproducibility, and they're getting better in terms of speed of acquisition and ease of use."
But even then, relying on a single test is not a good idea.
"How many tests do you need to do before you can reliably use the software package for the field or the OCT?" he asks. "While at three the thing actually kicks in and gives you a number, you really need five. You can have people who can change a lot if you do it once a year."
He recommends initially seeing a newly diagnosed glaucoma patient every three months, administering a field and imaging test twice in the first year to properly track changes. Once progression (or lack thereof) is properly assessed, patients can reduce the number of visits.
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