Demodex – the tiny mite with a (sometimes) big effect on dry eye disease.
Demodex (& Seborrheic) Blepharitis
Demodex is a tiny mite that can be the stuff of nightmares – not because it is truly worthy of a nightmare for the great majority of us, but at least because it looks like a Sci-Fi creature from outer space. The problem is that it is a common part of our “inner space” and can contribute to the inflammation responsible for dry eyes and irritated eyelids.
When Biotissue brought Cliradex out as a weapon against Demodex, they quoted internal studies suggesting that the likelihood of acquiring Demodex is roughly 10 percent per decade – implying that by the time we are 100 years old, we are 100% likely to be carriers of Demodex (this now appears likely by the age of 70 – see below). Diagnosis then was typically based on seeing signs of blepharitis (inflammation and irritation of the eyelids) and then pulling out a number of eyelashes to examine the roots for living mites – using a high-powered microscope (100x).
Subsequent studies have shown that the presence of collarets (smallish, greasy collars of waste products produced by these mites that create a “turtleneck-like collar” around the base of the lashes) is diagnostic of mite infestation – so most clinicians no longer rely on the older method to confirm that a patient has these mites. Using this method, it is estimated that as many as 58% of an eye doctor’s patient base can be affected – so my perception is that it is much more common than previously thought.
There are problems with general demographic studies like this. The first is that Demodex is not always a problem. There are many patients who have evidence of substantial colonization with this mite – yet have no evidence of damage or associated irritation. Second, and what is most obvious - is that if you have it – you have it (regardless of your age) and if it is causing problems (which it doesn’t always do), then we need to “fix the problem.”
You might ask, apart from a careful eye exam by a dry eye specialist, how would one feel or otherwise know if they might have DB – otherwise known as “Demodex Blepharitis?” In reports by Yeu et al (Yeu E, Holdbrook M, Baba S, Gomes PJ. Psychosocial impact of Demodex blepharitis. Presented at: ARVO 2021. Abstract 3544849) and Schacter et al (Schachter S, Yeu E, Holdbrook M, Baba S, Gomes PJ. Clinical manifestations of Demodex blepharitis. Presented at: ARVO 2021. Abstract 3546575) it was reported that as many as 80% of affected patients had some symptoms related to DB. This was mostly noted as “eye irritation” for 4 years or more prior to diagnosis. Redness of the lids and difficulty wearing makeup or contact lenses as well as functional issues such as difficulty with nighttime driving were also common complaints. Dry eye specialists find it to be a common cause for loss of eyelashes and as a co-contributor to dry eye disease (largely based on the inflammation caused by the irritation – that hurts tear producing cells and glands).
A drug company named Tarsus has found that a common veterinary product used to treat mange and mites in animals (0.25% LOTILANER ophthalmic solution), happens to be a good treatment for DB in humans and is calling it XDEMVY. They also sponsored an informational, nation-wide program to help eye specialists identify DB - and are calling it “Look at the lids.” Since the collaret formation is diagnostic, the trick is for doctors to pay attention to this area of the lashes – and fortunately, having a patient “look down” (while examining with the office microscope - called a slit lamp) - makes it easy for the doctor to make the diagnosis.
XDEMVY has been FDA approved for this indication, but the company predicts it may not be nationally available in pharmacies until the end of this month. From the company information relating to the clinical studies that found safety and efficacy, they note:
“About XDEMVY™
XDEMVY (lotilaner ophthalmic solution) 0.25%, formerly known as TP-03, is a novel prescription eye drop designed to treat Demodex blepharitis by targeting and eradicating the root cause of the disease – Demodex mite infestation. The active ingredient in XDEMVY is lotilaner, which is a well-characterized agent that eradicates Demodex mites by selectively inhibiting the mite’s GABA-Cl channels. It is a highly lipophilic molecule, which may promote its uptake in the oily sebum of the eye lash follicles where the mites reside. XDEMVY was evaluated in two pivotal trials collectively involving more than 800 patients. Both trials met the primary endpoint and all secondary endpoints, with statistical significance and no serious treatment-related adverse events. Most patients found the XDEMVY eye drop to be neutral to very comfortable. The most common ocular adverse reactions observed in the studies were instillation site stinging and burning which was reported in 10% of patients. Other ocular adverse reactions reported by less than 2% of patients were chalazion/hordeolum (stye) and punctate keratitis.”
Other drug treatments targeted for Demodex include various strengths and forms of TTO (Tea Tree Oil, and its related compounds, including Cliradex) available over the counter, as well as various prescriptive strengths and forms of Ivermectin (topical creams being the most common). The recommended discussion points eye doctors have been advised to use in discussing this common problem is cited here (From: https://eyesoneyecare.com/resources/co-morbid-systemic-disease-that-complicates-osd/?utm_medium=eoe:infinite-scroll):
“Example patient education script for Demodex blepharitis
“Demodex are small mites that live on our skin, specifically in our hair follicles and oil glands. It is completely normal for these mites to be there, as we will all have them at some point in our lives, and, normally, they do not cause any issues. However, in some cases, the number of mites present gets too high, which leads to a buildup of their waste on our eyelids and eyelashes which causes irritation and redness. They can also clog up our oil glands which can cause styes to form.
Because these mites are not a bacterium or virus they cannot be treated with antibiotic or antiviral medication, so this makes them a little more difficult to treat.
The treatment that does work on the mites is tea tree oil which comes from the tea tree plant. This oil is very strong so it can be irritating to the eyes when you use it, but a strong treatment is needed because the mites can be very difficult to get rid of. When you apply the oil make sure to get it on the lids and lashes, especially near the margin of your lids because that is where the mites live. Try to avoid getting any of the oil in the eye itself because you will feel a stinging sensation if you do, this will not damage your eye, but it will be uncomfortable for a little while.
Also make sure to use the oil on your cheeks, nose, forehead, and eyebrows because the mites can live in these areas as well. We cannot get rid of all the mites even with tea tree oil treatment, so our goal is to bring down the number of mites to the point where they no longer cause any issues. The mites do come back in some cases, so you may have to use the tea tree oil long-term if needed, but you may not have to use it as often.”
My personal preference in treating these mites when they arise to the level of causing inflammation and aggravating eyelids and dry eyes, is as follows:
First, I generally don’t start with Demodex-specific treatment unless it is clear there is an abundant load or unless other avenues of common lid hygiene have failed to reduce the blepharitis and related inflammation. This is in part related to the fact that most general lid hygiene strategies can effectively reduce the Demodex load and because total eradication is unlikely, regardless of the methods used. I also believe that introducing a problem to a patient that has no guaranteed cure and which may not actually be a problem at all for many, is setting the patient up for anxiety and failure. I will have an honest and often lengthy discussion for those who insist on debating these issues, but when I believe it is necessary, I recommend the following protocol:
- Begin with good lid hygiene. I’ve covered this in posts before. Since stagnant oil is the “buffet table” for bacteria and since bacteria and stagnant oil is the foodstuff of the mites, then clearing off the greater percentage of bacteria will “starve” the mites and getting god flow of oil will reduce the stagnation that leads to the buffet table.
- Second, treat the collars and “plaque” with a BlephEx treatment. I’ve posted on this before (and find the eyeThera shields particularly good for ensuring an optimal level of clean for most of these treatments). This gets rid of the “footing” for these germs and mites and opens the door for deeper penetration of mite-specific treatments like TTO and Ivermectin (and soon, XDEMVY).
- Apply the TTO (or Cliradex) compounds to the lids, forehead, brows, cheeks, nose and chin. I find this is easiest with Cliradex foam or wipes, though when I prescribe 1% Ivermectin cream (available as the trade named “Soolantra” or as generic or compounded products), I instruct patients to rub a tiny pea-sized dose between the tips of the index fingers and then lightly massage it into the 4 eyelids – up to the lash line – but preferably not into the eyes, as it will sting but not damage the eyes. Then apply a ½ inch between the index and middle fingers of both hands and massage it into the forehead, brows, cheeks, nose and chin. Do this every night (the mites are more active at night and are more likely to come into contact with these products then) and continue for 4-6 weeks (depending on the load of Demodex I see and the effect it appears to be having on the lids and eyes).
- During this treatment time, consider treating anyone else who sleeps in the same bed, the same way, as they are often also carrying the same mites (even if they have no symptoms) and can serve as a reservoir for re-infestation. Also wash all bed sheets, pillowcases, towels, facecloths, and other products that come in regular contact with the face, as they can serve as reservoirs, too.
- IPL with a heated expression (I like the off-label use of RF I’ve described) is a good, non-drug-related avenue for clearing up Demodex and other causes of blepharitis. The IPL can help knock off some of the mites and germs, reduce the inflammation (by also closing off some of the inflammation-bearing blood vessels) and stimulate the glands making tears just as the heated expressions can turn over the stagnant oils (and likely purge the glands of the mites and germs otherwise occupying them). Adding oral or topical antibiotics can also help in select cases, as can topical anti-inflammatory medications.
- An exam within a month or so of completion can help to judge if the treatment was effective. If significant amounts of mites remain or rebound, then retreatment is often necessary – but remember that total eradication is not often possible, so seeing a much-diminished number of collarets and less redness of the lids is often an effective endpoint.
- Since not all blepharitis is Demodex-related, it is generally necessary to continue daily, basic lid hygiene forever – and in cases of frequent re-infestation, adding a TTO product to daily care is sometimes advisable. Other blepharitis can include fungal and allergic/allergen-related causes, so working with a good dry eye specialist can be crucial to good care.
To schedule an appointment with Dr. Jaccoma, call Excellent Vision at either of these two dry eye offices:
(1) 155 Griffin Rd, Portsmouth, NH 03801 (603) 574-2020
(2) 3 Woodland Rd, STE 112 Stoneham, MA 02180 (near Boston) (781) 321-6463
(July 23rd’s post includes an index to past posts which will not include this post but is otherwise a complete reference!)