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What is Demodex blepharitis? | Causes | Diagnosis | Symptoms | Treatment | Prevention
Demodex blepharitis is an inflammatory eye condition associated with an overpopulation of Demodex—microscopic mites that live around hair and eyelash follicles. Many people have Demodex mites on their bodies and are often asymptomatic. However, an accumulation around the eyelid’s sensitive tissues can cause swelling, irritation, itching, and redness.
What is Demodex blepharitis?
Eye irritation has many causes, but blepharitis is one of the most common. Blepharitis is characterized by lid margin redness, inflammation, itching, and swelling. It can stem from a few different sources, including bacterial or viral infections, dandruff, allergies, and skin conditions like eczema or rosacea.
Demodex blepharitis, however, comes from an infestation of Demodex mites, which can block sebaceous glands, carry bacteria, and otherwise irritate the eyes. Even though many people are unfamiliar with it, Demodex blepharitis is an extremely common eye condition, affecting an estimated 25 million Americans. That includes nearly 58% of eye care clinic patients, according to a 2022 study. Still, it’s widely underdiagnosed, which is why it’s important to see an eye doctor if you experience blepharitis symptoms.
What causes Demodex blepharitis?
Demodex are microscopic, eight-legged mites that live on human skin around hair and lash follicles. They emerge at night to feed on epithelial cells and oil gland secretions. Demodex typically live on the face and around the eyes, which is why they’re sometimes called eyelash mites, but they can also migrate to the neck, chest, and arms.
Demodex mites are considered a normal part of the microorganisms that live in and on our bodies. They’re the most common microscopic ectoparasite, and they can play an important role in the facial microbiome, eliminating dead skin cells and helping to keep pores clear. They’re found in around one-third of children, half of adults, and two-thirds of seniors. Although harmless or beneficial in smaller numbers, with older age and certain health conditions, Demodex mites can be the underlying cause of blepharitis and, according to certain studies, rosacea as well.
Types of Demodex mites
There are two different types of Demodex mites—Demodex folliculorum and Demodex brevis—and they can irritate the eyes in a few different ways.
D. folliculorum feed on hair and lash follicles, which can cause microscopic abrasions. Over time, an accumulation of abrasions can thicken the lid and cause eyelash loss.
D. brevis, on the other hand, burrow into the glands inside the eyelid. That may obstruct the glands and cause inflammation.
Both types regurgitate some of what they eat, which can irritate the sensitive eye tissues. Plus, this waste can mix with Demodex eggs and form dandruff at the base of the eyelashes, called collarettes, which is a sign of Demodex blepharitis.
Risk factors
Even though anyone can have Demodex mites on the skin, risk factors for their overgrowth include a weakened immune system, dermatitis, acne, or skin infections. Anyone can develop Demodex blepharitis as well, although older adults and people with diabetes or rosacea may have a higher risk.
How is Demodex blepharitis diagnosed?
A healthcare provider typically begins by asking about symptoms, contact lens use, previous eye conditions, medical history, and other health issues.
If they suspect Demodex blepharitis, they will look at the eyelashes, specifically for collarettes or the mites themselves. Even when they’re clustered in large quantities, Demodex mites are invisible to the naked eye, so a microscope is needed to detect them.
“The best way to view Demodex mites is by taking an epilated eyelash sample and viewing the mite through a microscope,” according to Rebecca Rojas, OD, an Instructor of Optometric Sciences at Columbia University Irving Medical Center. A healthcare provider might also use a slit-lamp— a specialized microscope to observe the structures of the eye.
However, “the most common way to quickly assess for Demodex during a routine eye exam is to look at the base of lashes or near the meibomian glands for a collection of debris formed as waxy, cylindrical dandruff ‘hugging’ the lash follicle,” says Dr. Rojas. “Having the patient look down and seeing these collarettes is a good indicator of Demodex presence without having to observe an epilated hair follicle microscopically.”
One study showed that 100% of patients with this cylinder-shaped dandruff had Demodex blepharitis. Even so, Demodex blepharitis shares many symptoms with several other eye conditions, so it’s widely misdiagnosed as dry eye disease, allergies, conjunctivitis, ocular rosacea, or bacterial blepharitis.
How do I know if I have Demodex blepharitis?
“Some patients may be asymptomatic, while others can have symptoms which can range in form and severity,” says Dr. Rojas. Demodex blepharitis shares certain symptoms with ocular surface diseases like dry eye disease and infections like pink eye (conjunctivitis), but they’re three different conditions.
Symptoms of Demodex blepharitis vs. dry eye vs. pink eye |
||
|---|---|---|
| Demodex blepharitis | Dry eye | Pink eye (conjunctivitis) |
| Burning | Burning | Burning |
| Erythema (skin redness) | Red eye(s) | Red eye(s) |
| Swollen eyelid | Dryness | Swollen eyelid |
| Itching | Gritty or scratchy sensation | Itching |
| Discharge | Blurry vision | Discharge |
| Eyelid crusting or flakes | Sensitivity to light | Sensitivity to light |
| Foreign body sensation | Foreign body sensation | Watery eyes |
| Collarettes | ||
| Loss of eyelashes |
How to get rid of Demodex blepharitis
Since Demodex are parasites, they won’t respond to antibacterial, antiviral, or antifungal treatment. Managing Demodex blepharitis can be tricky, but if untreated, it can lead to other problems like styes, chalazion, corneal ulcers, and meibomian gland dysfunction. It’s a chronic condition, but the good news is that there are a few viable treatments.
Natural remedies
Tea tree oil
James Dello Russo, OD, an optometrist at New Jersey Eye Center, says, “lid scrubs containing tea tree oil have been particularly effective in managing the proliferation of Demodex infestations,” specifically citing Oust by Ocusoft. Studies have shown that tea tree oil is effective in reducing Demodex mites. However, tea tree oil, especially at full strength, can be irritating to the eyes, so only use formulations that are meant to cleanse the eyelids.
Manuka honey
Since ancient times, people have valued honey for its medicinal properties, and manuka honey, from bees that pollinate New Zealand’s manuka bush, is a potent antimicrobial. People commonly use it to treat wounds and burns, but it may also promote digestive health, soothe sore throats, and help treat certain skin conditions.
One study from 2020 found that eye cream containing manuka honey helped treat blepharitis from a variety of causes, including Demodex mites.
Warm compresses for symptom relief
Running a cloth under warm water and holding it against your eyelids for around five minutes may help reduce eyelid swelling, remove sebaceous gland blockages, and ease ocular irritation. However, it doesn’t address the root cause of Demodex blepharitis—the accumulation of Demodex mites. Used alongside another treatment, though, it can help ease symptoms.
Blepharoexfoliation
This in-office procedure involves a tiny, rotating micro-sponge that the doctor can use to exfoliate the eyelid. It removes the biofilm on the lid that serves as a home for Demodex mites. Blepharoexfoliation typically supplements at-home eyelid scrubs, and a recent study showed that this combination reduces patients’ Demodex count more effectively than at-home scrubs alone.
Medications
Xdemvy
Until 2023, the Food and Drug Administration had not approved any prescription medications for Demodex blepharitis treatment. However, after clinical trials proved Xdemvy (lotilaner ophthalmic solution) effective in eliminating mites and reducing collarettes, the administration gave it the nod. Developed by the company Tarsus, Xdemvy causes paralysis and death in the mites.
“Your doctor can prescribe this prescription drop, used twice a day for six weeks, to help eliminate Demodex infestations,” says Dr. Dello Russo. “So if you are potentially suffering with this chronic condition, help is available from your optometrist or ophthalmologist.”
Blepharitis patients in the clinical trials showed significant improvement in that time frame, and some saw a reduction of collarettes in as few as 15 days.
Ivermectin
This is an antiparasitic drug that doctors typically prescribe for people with infections caused by roundworm infestations, like strongyloidiasis or onchocerciasis. Doctors sometimes use certain topical treatments of ivermectin to treat skin conditions like rosacea and scabies, and clinical research has shown that a 1% cream can effectively treat Demodex blepharitis too.
Metronidazole
Metronidazole is an antibiotic prescribed for some bacterial infections and skin conditions like rosacea. Metronidazole as a topical or oral treatment has been found to reduce Demodex mites as well.
Preventing Demodex blepharitis
Demodex blepharitis itself isn’t contagious. But the mites may spread via close contact with someone who has them. Preventing this spread is nearly impossible since they’re so prevalent and often asymptomatic. However, Dr. Dello Russo says focusing on good eyelid hygiene is one of the most effective ways to minimize the occurrence of Demodex blepharitis.
Dr. Rojas agrees and recommends cleansing your eyelids and eyelashes daily as a standard preventive measure. Or, to prevent flare-ups of a chronic condition, she suggests washing pillowcases, sheets, and bedding in hot water and drying on high heat, discarding old make-up, not sharing makeup products, and limiting heavy oil-based cleansers or greasy creams or cosmetics.
Bottom line: Demodex blepharitis is treatable
Demodex mites are almost unavoidable since so many people have them. Most of the time, they’re completely harmless, but they can occasionally accumulate, causing blepharitis. Even though it’s chronic and often mistaken for other conditions, with a correct diagnosis, Demodex blepharitis can be treated. It often responds to cleansing and scrubs or shampoos that contain tea tree oil, but also to drugs like Xdemvy.
The most important part is determining whether your eye condition is caused by Demodex or something else. This requires the keen eye of a doctor. If you’re experiencing redness, irritation, swelling, itching, or discharge in one or both eyes, be sure to see a healthcare provider for an effective treatment.
Sources
- Demodex blepharitis: a comprehensive review of the disease, current management, and emerging therapies, Eye & Contact Lens (2023)
- The prevalence of Demodex blepharitis in U.S. eye care clinic patients as determined by collarettes: a pathognomonic sign, Clinical Ophthalmology (2022)
- Are tiny mites causing your blepharitis? American Academy of Opthalmology (2022)
- Sensitivity and specificity for the detection of Demodex mites with slit-lamp in patients with blepharitis, Investigative Ophthalmology and Visual Science (2022)
- Mite-related bacterial antigens stimulate inflammatory cells in rosacea, British Journal of Dermatology (2007)
- Demodex blepharitis: clinical perspectives, Clinical Optometry (2018)
- High prevalence of Demodex in eyelashes with cylindrical dandruff, Investigative Ophthalmology & Visual Science (2005)
- In vitro and in vivo killing of ocular Demodex by tea tree oil, British Journal of Ophthalmology (2005)
- Randomized masked trial of the clinical efficacy of MGO Manuka Honey microemulsion eye cream for the treatment of blepharitis, The Ocular Surface (2020)
- Lotilaner Ophthalmic Solution 0.25% for Demodex Blepharitis: Randomized, Vehicle-Controlled, Multicenter, Phase 3 Trial (Saturn-2), Harvard Medical School Department of Ophthalmology (2023)
- Role of blepharoexfoliation in Demodex blepharitis: a randomized comparative study, Cornea (2023)
- Efficacy of topical Ivermectin 1% in the treatment of Demodex blepharitis, Cornea (2022)
