Demodex blepharitis

Demodex blepharitis is caused by mites that infest the eyelash follicles, where they cause damage via mechanical, chemical, and bacterial mechanisms.

Demodex mite infestation contributes to the formation of cylindrical, sleeve-like coatings at the base of the eyelashes. These collarettes are composed of partially digested epithelial cells, mite waste (faeces), and eggs. The cylinders at the base of the eyelashes are considered to be the diagnostic sign of Demodex blepharitis.

There are two varieties of Demodex that infest the surface of the eyes. Demodex folliculorum infests the eyelash follicles, where they scrape with their claws and excrete digestive enzymes to feed on the oily sebum deep in the follicles, causing irritation, inflammation and redness.

Demodex brevis prefers the rich Meibum in the Meibomian glands on the posterior eyelid margin, and they are infested themselves with bacteria on their surface and in their gut, causing inflammation of the surrounding tissues. They also infest the skin of the face contributing to redness of the facial skin and Rosacea.

Symptoms of Demodex blepharitis include eyelid margin redness, eyelid oedema (swelling), keratitis (inflammation on the surface of the cornea), eyelash misalignment and loss, meibomian gland dysfunction (oil gland blockage), and tear film disruptions. There can also be recurrent chalazia (lumps in the eyelid) and permanent damage to the cornea. It is unknown the effect of long-term inflammation in the tear film, where some toxic components pass into the eye. When there are significant signs of Demodex one study found an average of 3 Demodex mites per eyelash.

In-Clinic Treatment
Tea tree oil with its terpinen-4-oil active ingredient is effective in having acaricidal effects (anti Demodex). It is carefully applied to the base of the eyelashes and this anti-mite treatment is very effective in reducing mite infestation. The in-clinic application is stronger than that available over-the-counter.

For us this is the Dry Eye Spa Clinic(TM)

The life cycle of Demodex is 14 to 16 days, so commonly the treatment session is repeated after ideally 2 or otherwise 3 weeks. Tea tree oil application can be irritating (16% of people), so for those who are sensitive to Tea tree oil there is an alternative, and this is Okra treatment. A comparative study in 2021 found Okra to have similar efficacy to Tea tree oil for Demodex eradication and control. Another treatment that has been studied is topical Ivermectin solution applied to the eyelids.

In-office mechanical debridement of the lid margins can also be helpful and is termed a Blephex™ treatment. This is a deep scrub of the base of the eyelashes to mechanically dislodge the Demodex mites. This is in addition to Tea Tree Oil or Okra treatment.
In the USA Lotilaner™ is available and this is an antiparasitic agent that induces spastic paralysis and death in Demodex mites by selectively inhibiting parasite-specific γ-aminobutyric acid chloride channels, but not human γ-aminobutyric acid chloride channels. It is applied twice a day to the eyelid margins but is not yet available in Europe or the UK.

At Home Treatment
Optase™ gel is a weak concentration of Tea tree oil that does not require prescription. It is applied to the closed eyelids, specifically rubbed into the base of the eyelashes. People also use Tea tree oil face wash and shower gel (New York Biology Tea tree body wash).

None of these should be used if there is sensitivity or allergy to Tea tree oil.

An alternative is Okra, which can be obtained as wipes.

Zocular ZocuWipe Eyelid Wipes with Okra Complex - 30x Eyelid Cleanser. These are comparatively expensive but are equivalent to Optase gel and are considered less irritant than Tea tree oil.

The key to long-term clearance is to avoid reinfection from mites at home. The best way to remove Demodex mites from home is by steam cleaning carpets and furniture and regularly removing dust with a damp mop or rag. Bedding should be washed weekly in hot water to kill Demodex mites, especially if you struggle with allergies. The minimum temperature is 60 degrees Centigrade. Wash pillows and replace them after a year.

After prolonged use, a pillow is covered in skin oils, germs, and drool. After two years of daily use, up to 30% of a pillow’s weight comprises dead skin cells, mites, and their faeces.