Problems with eye drops

 Here’s something that users of eye drops might find helpful—or at least interesting. I read about a woman who had lots of problems with her eyes—an abnormal membrane on her retina; glaucoma; cataracts. She used pressure-reducing eye drops for her glaucoma, and ocular antibiotic and steroid drops as well as artificial tears for her other ailments. After her cataract surgery, she found she was intensely sensitive to light. Also, when she used her glaucoma drops her eyes began to burn, and her eyes were dry and gritty feeling. She stopped all the drops and the problems went away.

It turns out that eye drops contain a preservative called benzoalkonium chloride (BAK). BAK, a soap-like compound, prevents the growth of bacteria in bottles of medications that contain more than a single dose. It is the most commonly used preservative in both over-the-counter and prescription eye drops. BAK kills bacteria by dissolving their protective outer coat. The problem is that our tears are covered by a similar protective coat. The BAK in eye drops breaks down the protective coat in our tears, exposing the salty fluid to the air. The unprotected fluid evaporates and our eyes become even dryer. If you make enough tears, the drops won’t bother you. But aging reduces this protective layer, which puts older users of medications containing BAK at higher risk of drying eyes. The dryness can eventually lead to permanent damage to the cornea, the clear outermost layer of the eye. (As to the woman I described above, she switched to single-dose bottles of drops, which don’t need preservatives.)

When the optometrist puts drops in my eyes to dilate them, the drops really burn. She says it’s because I have dry eyes and that I should use lubricant drops. So I bought some Systane. It contains a preservative called Polyquad, which is similar to BAK, but it’s a larger molecule and is “not internalized by the epithelial cells on the eye, so it doesn’t cause the kind of toxicity that BAK causes,” according to the Review of Opthalmology. But I hate putting drops in my eyes so I never use it anyway.

For an introduction to this blog, see I Just Say No; for a list of blog topics, click the Topics tab.