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BAK sensitivity may masquerade as viral conjunctivitis
When faced with a red eye, consider all possible etiologies.
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Red eyes may have many possible etiologies, such as viral, bacterial or allergic conjunctivitis. However, it is important to consider sensitivity to benzalkonium chloride in patients who present with a viral-type infection with similar symptoms.
History of BAK
BAK was first introduced in the early 1900s as a detergent and an ammonium compound and became more popular in the 1940s in the ophthalmic industry. It was used primarily to preserve hard contact lens solutions. Pharmaceutical companies use BAK as a preservative because of its extreme efficacy and ability to fight off microbial contamination of the bottle. However, it also has the ability to break the cell junction in the epithelium,
to gain access to the cornea.
Mel Friedman
Studies have shown the detrimental effects of BAK, which include induced necrosis and cellular apoptosis, caused by BAK’s ability to disturb the cellular membrane in the bacterial cells. The corneal surface is similar to bacterial cells; the cornea becomes more sensitive to the effects of BAK as the frequency of use increases. As a result, the breakdown of corneal epithelium increases along with corneal permeability, which causes BAK toxicity. BAK has also been shown to disrupt tear break-up time by interfering with lipid components and causing tear film instability (Pauly et al., Sarkar et al., Ye et al.).
The following case details my experience diagnosing and treating a patient who presented to my practice and, without a doubt, had adenovirus. However, another factor lingered that I had yet to discover.
Case report
A 58-year-old man presented to my office with a 1+ injected bulbar conjunctival appearance. His cornea was clear, and his anterior chamber was quiet. I ran the AdenoPlus (Nicox Inc., Dallas) diagnostic test to rule out or confirm adenovirus in the eye, and the test result was positive. I treated the patient with Zylet (loteprednol etabonate 0.5%/tobramycin 0.3% ophthalmic suspension, Bausch + Lomb) – an antibiotic and steroid combination – intended to quiet inflammation and prevent bacterial infection. The patient’s eye improved within the week.
However, about a week and a half later, the patient presented again with a 2+ conjunctival injection in the same eye. His visual acuity was within normal limits of 20/20 in both eyes. Because his cornea was still clear, and his anterior chamber was quiet, I prescribed Lotemax suspension (loteprednol etabonate ophthalmic suspension 0.5%, Bausch + Lomb) four times daily.
After 4 more days of persistent redness, the patient still had a conjunctival area that was 1+ to 2+ injected. The chamber was still quiet, the cornea was clear, and the patient has no complaints of pain, itching or other subjective symptoms. His vision and pressures remained normal.
Perceived acute conjunctivitis can have many possible etiologies.
Image: Friedman M
With these factors in mind, I asked the patient to continue the steroid drop three times a day for another 3 to 4 days. The redness did not improve over that period of time, and the patient’s IOP was still normal. Because his presentation was so similar to that initially, I conducted another AdenoPlus test, which was negative.
Upon reviewing the case, I saw that the patient initially exhibited adenovirus symptoms both objectively and subjectively. The second time he presented, he exhibited an adenovirus sign, but this time, with no discomfort. I concluded that the possibility existed that the patient had sensitivity to BAK.
I found that the BAK percentage in the first drug prescribed was 0.01%, a fairly strong concentration. The patient still had a 2+ injected red eye. I then prescribed Durezol (difluprednate ophthalmic emulsion 0.05%, Alcon), a steroid with no BAK, and the patient’s eye cleared within a day.
To challenge my theory of a BAK allergy, I initiated a challenge–dechallenge–rechallenge by giving the patient another ophthalmic drop containing 0.005% BAK, the lowest possible concentration in drops. Unsurprisingly, the patient’s red eye returned. By weighing the effects of medications containing BAK against the ruling provided by AdenoPlus, I confirmed that BAK sensitivity was the cause of the patient’s red eye, and proper steps were taken to resolve the issue.
This case served as a sobering reminder that preservative-related medicamentosa can be vexing and that a complete cessation of all preserved eye drops is sometimes indicated.
In the past, I concluded there may have been a toxicity effect of being overmedicated in some of my patients. In retrospect, I am now more inclined to think that those patients may not have experienced toxicity, but instead, sensitivity to BAK.
It is critical to realize that a red eye with perceived acute conjunctivitis can have many possible etiologies. Accordingly, a comprehensive approach to red eye management is necessary and encouraged.
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Disclosures: Friedman is a consultant to Bausch + Lomb and Allergan Inc.