Blepharitis ...? Who knew?

I know you've seen the ads on TV and social media. Suddenly, we have something new to worry about: Demodex blepharitis. Who knew that tiny burrowing mites could be living in our eyelashes? I worked with a guy named Woodbury who had red, swollen eyelids in both eyes. We didn't ask him about it, but one day Woody told us the condition was called "leferitis." So, although I was familiar with the disease, I never knew how it was spelled or pronounced until now.

Demodex refers to a species of tiny parasitic mites related to spiders and ticks. Blepharitis is from the Greek word "blepharon," meaning "eyelid," with the suffix "-itis," denoting inflammation. Thus, blepharitis refers specifically to the inflammation of the eyelid margins.

There are two main species of Demodex that live on humans:

Demodex folliculorum usually lives in smaller hair follicles, especially in your eyelashes. They eat skin cells.

Demodex brevis usually lives near the oil glands in hair follicles. They eat sebum, a greasy substance made by oil glands. The adult mites are 0.3–0.4 mm long.

In July 2026, Tarsus Pharmaceuticals, Inc. launched a consumer-awareness campaign that substantially increased public recognition of Demodex blepharitis from about 2% at the start of the campaign to 30% at the end. That’s why we saw so many ads appear in July and August 2026.

Estimates of how many of us are infected with this parasite vary widely. In one U.S. study, the mites were found in 57.7% of 1,032 people visiting eye-care clinics.  In fact, the mites cannot be directly observed because they live down in the hair follicle. Their presence is inferred from the collarettes, which are scaly, waxy, crust-like debris that wraps around the base of your eyelashes, looking like a 'collar.' They’re caused by the waste and dead skin cells left behind by Demodex mites. If you have these collarettes, you almost certainly have a Demodex mite blepharitis problem.

What should you do about the mites? Most ophthalmologists agree that if you don't have symptoms of blepharitis, there's no reason to worry about them. If you do have them, you've probably lived with them your entire life without knowing it.

That leads me to wonder about the ancient legend of the Sandman who sprinkles sand in the eyes of sleeping children. That story may have come about to explain those gritty particles in your eyelids when you wake up in the morning.