OTC cold, flu care: What patients don’t know can hurt them

If cold and flu season wasn't unpleasant enough, the same over-the-counter (OTC) medications patients use to kick common colds could trigger an ophthalmic emergency that's anything but common.

In susceptible patients, pharmacologically induced acute angle-closure glaucoma (ACG) is a serious, painful and potentially sight-threatening emergency that can result in blindness if not immediately relieved. Uncommon but not rare, acute ACG attacks triggered by a drug interaction most often occur in patients unaware of their susceptibility due to an anatomical abnormality of their eye. Accordingly, it's the sudden onset of unbearable eye pain, severe headaches, blurred vision and nausea that clue patients in to an emergent situation—and even then, glaucoma isn't likely their first thought.

Glaucoma, the second-leading cause of blindness in the U.S., is typically a gradual, progressive increase of IOP that can irreversibly damage the optic nerve. But unlike the slow, painless increase in pressure associated with the most common form of glaucoma, primary open-angle glaucoma (POAG), acute attacks of ACG happen suddenly and with no warning.

It all comes down to the drainage angle.

Off the angle

Anatomically, the angle is the point at which the cornea and iris meet, a locale where the trabecular meshwork drains aqueous humor via the anterior chamber. Typically, this angle is about 45 degrees. ACG occurs when that angle closes or becomes obstructed, inhibiting drainage of aqueous humor and increasing pressure.

Shorter (farsighted), smaller and older eyes are more susceptible to ACG because that angle tends to be narrower naturally as a result of structural crowding. Conversely, a person with narrow angles may never know their risk until that angle suddenly closes. And that's precisely the circumstance that OTC cold medications could precipitate, says Jimmy Bartlett, O.D., professor emeritus at the University of Alabama-Birmingham School of Optometry.

"These products do have potential to dilate the pupil and precipitate significant and painful issues in people with narrow angles," Dr. Bartlett says.

When good OTC drugs bite

Glaucoma patients are routinely advised against taking certain medications that are known to elevate IOP, such as some systemic or topical medications. While patients with glaucoma should always consult their doctor regarding medications they take, generally, OTC cold medications wouldn't affect most glaucoma patients. The exception being patients with narrow angles.

The key ingredients of OTC cold medications—antihistamines and sinus decongestants—can potentially induce pupillary mydriasis, or dilation of the pupil. In eyes with already narrow angles, pupil dilation may effectively close that angle and trigger an acute attack. Consequently, it's also why eye doctors may forgo pharmacological dilation in patients determined to have narrow angles and recommend laser iridotomy to hedge against ACG.

In a more than four-decade career, Dr. Bartlett never encountered a pharmacologically induced acute ACG attack associated with an OTC medication, but that doesn't mean they don't happen. Case reports and media reports do describe such infrequent occurrences in the past several years.

"It's possible that a person with cold or flu, or sinus congestion, could go into a pharmacy at this time of year and pick up a product that may contain medications that dilate the pupil and trigger an attack," Dr. Bartlett says. "Is it possible? Yes. Is it common? No."

So there's a chance

Still, ACG is a relatively uncommon condition in the U.S. that accounts for only a small portion of all diagnosed cases of glaucoma. However, its importance as a health care issue is far greater than the relatively small number of cases would suggest. Prompt diagnosis and effective treatment are critical to preserving vision in the event of an acute attack, and even earlier intervention in the form of prophylactic treatment can protect the eye against sudden or repeated attacks or chronic angle closure, notes AOA's Care of the Patient with Primary Angle-Closure Glaucoma.

Dr. Bartlett says the takeaway for doctors of optometry is to ensure patients with narrow angles are informed and aware of the potential OTC cold medications could have on their eye health. Likewise, it's important to uncover all medications that could have precipitated angle closure in patients presenting with such symptoms.

"This is an emergent condition and not something that can wait several days in most instances," Dr. Bartlett adds.