What is blepharitis?

Blepharitis is a common condition among eye care providers and characterized by chronic inflammation of the eyelids. It can cause redness, itching, burning, and sometimes even crusting of the eyelids.

Blepharitis can be categorized into two main types: anterior and posterior blepharitis.

Anterior blepharitis affects the front edge of the eyelids and is typically caused by bacterial overgrowth and responds well to routine treatments, such as antibiotics. In some cases, however, patients do not respond to standard treatments, leading to persistent irritation and eye symptoms.

Posterior blepharitis affects the inner eyelid and is commonly associated with dysfunction of the meibomian glands, which produce the oily component of tears.

What are the rare causes of anterior belefaritis?

Anterior blepharitis can have several lesser-recognized causes, including contact dermatitis, allergic reactions, fungal infections and infections caused by bacteria other than Staphylococcus. If a patient with blepharitis does not respond to normal treatments, such as antibiotics or antivirals, demodicosis should be suspected. In such cases, other potential causes should be explored, and one of the top suspects should be the parasitic mite—Demodex.

Though blepharitis is common, Demodex is often overlooked and may be a gross underestimated as the causative organism. About half of blepharitis cases now show symptoms of Demodex blepharitis and are diagnosed as such.

There can be several causes for the condition, however one often overlooked cause is an overgrowth of Demodex mites. Therefore, I would like to focus here on demodex blepharitis.

Is Demodex a harmful parasite for skin and eye health?

Demodex are ectoparasitic tiny mites that naturally live on human skin, including the eyelashes and eyebrows. The mites can also be found on the skin of the cheeks, nose, forehead, and in the eyebrows as well. The typical lifespan of Demodex is about 3 weeks. Demodex mates in the openings of hair follicles and lays its eggs in hair follicles or sebaceous glands.

These mites are typically harmless and are found in hair follicles and sebaceous glands as part of the skin’s natural microflora. Normally, they do not cause any problems. However, in some cases, an excessive population of Demodex mites can lead to Demodex blepharitis (eyelid inflammation) and several other ocular conditions such as meibomian gland dysfunction (oil gland problems), conjunctivitis, keratitis and eyelash disruption. These conditions might result in symptoms like itching, redness, irritation, and dry eyes. In addition to discomfort, patients reported functional issues, like difficulty with nighttime driving.

What are the symptoms for Demodex blepharitis?

The most common symptoms of DB presenting as foreign body sensation, burning, stinging, epiphora, transiently blurred vision, and general irritation. Dysfunction of the meibomian (oil) gland due to demodicosis could eventually lead to dry eyes.

The signs of Demodex blepharitis are easily recognizable in the form of characteristic waxy debris, known as cylindrical collarettes, wrapping around the bases of the eyelashes. Other signs include redness at the eyelid margins and recurrent hordeolum (sty) and chalazion.

How is Demodex blepharitis effectively treated today?

Because these mites are not a bacterium or virus they cannot be treated with antibiotic or antiviral medication and surprisingly they are resistant to other antimicrobial agents such as alcohol and povidone-iodine, so this makes them a little more difficult to treat. Though it has traditionally been used to treat blepharitis, the use of baby shampoo should be avoided as not only does it fail to eradicate Demodex, but it can have a detrimental effect on the tear film as well.

  1. Tea tree oil: The most effective treatment for mites is tea tree oil, which is extracted from the tea tree plant (Melaleuca alternifolia). The active ingredient in tea tree oil is 4-terpineol, which has broadly antimicrobial and most importantly demodicidal properties. Tea tree oil is most commonly found in the form of cleansing wipes, gel or shampoo containing 2-5% of the substance.

    This oil can be irritating to the eyes, but it is almost the only way to get rid of mites. When applying the oil, get it on the eyelids and eyelashes, especially at the edge of your eyelids. Make sure you also use the oil on your cheeks, nose, forehead and eyebrows, other areas where mites like to live.

    It is recommended that the treatment last at least 6 weeks, as this corresponds to two life cycles of the mites. The goal of treatment in Demodex blepharitis is not the complete eradication of the mites, as this goal is usually not achieved, but rather the reduction of mite population.
  1. Lotilaner 0.25% solution (Tarsus Pharmaceuticals): It is an antiparasitic (acaricide = mite killer) agent that eliminates Demodex mites. This new ophthalmic solution is the first FDA-approved medication to treat Demodex-related blepharitis. Results from the clinical trials with topical lotilaner ophthalmic solution are promising. Significant mite eradication and meaningful improvements in inflammation were achieved after 6 weeks of treatment with lotilaner.
  1. Hypochlorous acid (HOCl): produced by leukocytes of the immune system as a natural antiseptic agent. It has been suggested that it may reduce the number of demodex, but its effect against to demodex is controversial. Even if hypochlorous acid is not demodicidal, its broad antiseptic activity can help treat Demodex blepharitis by reducing the number of bacteria present on the eyelids, eyelashes, and the surface of Demodex mites. Therefore, after initial treatment with tea tree oil, they may use tea tree oil and hypochlorous acid together to provide two separate eyelid hygiene mechanisms.
  1. Intense pulsed light therapy (IPL): IPL functions through the delivery of high intensity polychromatic light (515-1200 nm) to the target tissue. The use of IPL for the treatment of evaporative dry eye is widely supported and is FDA-approved for these indications. In cases of Demodex blepharitis, IPL treatment can be a ideal treatment option, because IPL has been shown to be demodicidal. Demodex absorbs the energy provided by the pulsed light, which leads to a rapid heating that results in the death of the mite. Furthermore, IPL treatment reduces the number of bacteria present and reduces inflammation through photobiomodulation.
  1. Due to the lack of definitive treatment for Demodex blepharitis and the lack of preparations for ophthalmic use, there is increasing interest in off-label usage of antiparasitic medications approved for dermatologic use in combination with eyelid hygiene through the use of tea tree oil or terpinen-4-ol.
    • Ivermectin 1% cream (Soolantra, Galderma): Researchers have reported positive results with this topical rosacea remedy. The ointment can be used as a bedtime lid scrub for one to two months. Ivermectin ointment works very well, but patients can expect a temporary increase in inflammation and discomfort during the first few days of treatment as a large number of mites are killed.
    • Permethrin 5% cream: There are many patients with Demodex blepharitis treated with off-label use of permethrin 5% cream, which is FDA labeled for use against scabies.
    • Oral ivermectin: The oral formulation of ivermectin is another effective and relatively economical option. Patients take one to three weight-based doses, spaced one week apart.
    • Metronidazole: According to some studies, a combination of ivermectin and metronidazole could reduce the number of mites more than either drug alone. The combination could be administered either topically or orally.
  2. It is also recommended to discard previously used make-up and to routinely wash towels and bedding.

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