Street Smarts

When Glaucoma Isn't Really Glaucoma

Read your textbooks, listen to your professors, then add these two simple concepts to your body of knowledge.

By Dan Beck, O.D. Leland, N.C.

ONE OF OUR MOST REWARDING — and most frustrating — clinical challenges is diagnosing and treating glaucoma. On one hand, preserving vision despite a debilitating disease can give you a reason to get out of bed in the morning and even ward off job burnout. But because glaucoma is a group of anomalies and not one specific disease, making a proper diagnosis and administering effective therapy can be difficult. Often, the most straightforward patients are misdiagnosed, usually because the doctor fails to properly analyze the patient as a whole and places too much emphasis on intraocular pressure (IOP).

I won't bore you with research findings or the pharmacology of glaucoma medications. You have textbooks for that information. Rather, I'll present two basic ideas that are frequently ignored or not considered in glaucoma management.

IOP Without Pachymetry Is Meaningless

It wasn't until fairly recently that we began taking corneal thickness into account when measuring IOPs. In the 13 years I've been practicing, I've seen a good number of patients who were diagnosed with open-angle glaucoma by another practitioner and had been using drops for years. Their optic nerve head cuppings and visual fields were normal but, collectively, the average corneal thickness was above 600 µm. Had this been measured and taken into account, all these patients would have had pressures around 17 mm Hg to 18 mm Hg. These patients had years of expense and the hassle of using topical medications for a disease they didn't have! Be aware that there are still many doctors who treat glaucoma without ever having performed pachymetry.

Family History of Glaucoma Is Mostly Meaningless

When a patient says he has a family history of glaucoma, I take that information with a grain of salt. Many patients confuse glaucoma with cataracts. The eye surgery that Mom had was probably cataract removal not glaucoma surgery. I ask if the parent has been taking or was prescribed eye drops for more than a year. That helps confirm the diagnosis.

If a patient is certain that Mom was diagnosed with glaucoma, I also take into account that the doctor who diagnosed her may be a lunatic and not know what he or she is doing. Just because Mom is taking a prostaglandin drop at bedtime, doesn't necessarily mean she has glaucoma. Maybe she's one of those people who has a pach reading over 600.

The genetics of glaucoma is still based primarily on circumstantial evidence and has yet to be properly explained. If Mom has glaucoma and one of her kids also has it, it's usually recorded as genetic. In true scientific terms, however, that's junk science to the extreme.

Get the Big Picture

Glaucoma is an extremely complex phenomenon. We must use every relevant test and all the reliable data we have or risk a misdiagnosis. Be careful about believing what every other doctor who has treated your patient has concluded. His diagnosis may be based on old concepts. It's up to you to look at the whole patient with a fresh eye.nOD