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This “mite” be gross

By Sasha L Radford, OD


Look with me through the microscope:  The eyelid margins are red with scales or crusts around the lashes. The eyes themselves are a little red as well, and there are other signs of chronic inflammation such as clogged oil glands and loss of eyelashes. A key observation points to a very specific problem: cylindrical “cuffs” of crusty material encircling the base of the lashes. I ask my technician for a pair of jeweler’s forceps – very tiny, precise tweezers – grasp an eyelash, and twirl it around gently while observing under the highest magnification setting. Ah ha! There it is! My suspicious are confirmed and I know exactly what to do.

All too often I see patients with red, irritated, crusty eyes. These symptoms are commonly attributed to allergies or dryness but there’s another potential culprit that’s often overlooked. Not many people consider that the eyelids themselves can be inflamed or infected but this is actually a common problem which often goes untreated.

Blepharitis, or inflammation of the eyelids, is most frequently caused by Staph bacteria that normally live on our skin. There are other causes; appropriate treatment is based on the underlying source of inflammation.

There are many examples in medicine of conditions that suddenly get a lot of press. Occasionally it’s a newly discovered disease – new technology makes it possible to detect and diagnose. Other times we know about a condition all along but treatment has only recently become known or a more effective treatment becomes available.

Demodex blepharitis is an example of the latter. Pick up any eye care journal from the past year and there’s at least one article about it. Demodex is a cause of blepharitis that we’ve known about for decades but haven’t been able to treat successfully; now, a new treatment has brought Demodex blepharitis to the forefront of eye care. A fair warning: if you’re squeamish about your eyes and critters in particular, stop reading now.

For those of you still hanging in there because you’re fascinated by repulsive ailments, you won’t be disappointed. Demodex is a tiny, parasitic mite that lives in the hair follicles of the face, brows, and eyelashes. Most adults are unknowingly infested with these to some degree; they usually don’t cause any problems. Sometimes the mites can cause inflammation in the eyelids leading to red, irritated eyes and the trademark appearance of crusty cuffs around the base of the lashes.

Eye doctors used to have to pluck out a lash, hope a few mites cling on, and search for them under a light microscope, which isn’t available in most optometry practices. Now, there is a simple procedure using the slit lamp biomicroscope. As described above, by grasping a lash with jeweler’s forceps and twirling it gently, mites living in the follicle under the surface wake up; at the highest magnification setting, their tails can be seen to pop up next to the eyelash. I have to admit, I get a little excited every time I see this – the sort of excited that’s usually coupled with mild nausea. But it is exciting, as a doctor, because once I identify the cause of the inflammation, I know I can treat it and make the patient feel better.

Demodex blepharitis has traditionally been treated the same as other varieties of blepharitis – daily lid scrubs using medicated disposable wipes – which can help temporarily but do nothing to reduce the population of the mites themselves. Now we know that an ingredient in tea tree oil is toxic to Demodex mites and ocular formulations are now on the market in the form of convenient lid scrubs.

Routine eyelid hygiene with a safe tea tree oil product made for ophthalmic use can keep their numbers low enough to stop the inflammation and discomfort. There is no way to completely eradicate them; unfortunately, at least for now, the mites are here to stay.