Dry Eye: Demodex

WHAT IS DEMODEX?

Demodex are ectoparasitic mites that inhabit our hair follicles and oil glands. When the population of Demodex in our eyelids overgrows, homeostatic balance is lost, and symptoms such as eyelid itching, dryness, irritation, foreign body sensation, epiphora, redness, inflammation, and even lash loss can occur. The mites will then cause mechanical damage to the skin cells and oils from the meibomian glands. This in turn increases the inflammation as the by-product of the mites eating the oil will physically block the openings of the meibomian glands.

While these signs and symptoms are concerning, they can also be observed in numerous other ocular surface diseases, such as blepharitis and meibomian gland dysfunction. It is important to visit your optometrist so that he/she can assess whether demodex is a source of the dry eye symptoms. A telltale sign in the form of lash collarettes, which are a waxy buildup of debris around the base of the lashes. These collarettes are considered pathognomonic for Demodex, so diagnosis is straightforward under a slit lamp microscope.

HOW TO EFFECTIVELY TREAT DEMODEX?

The best treatment for Demodex infestations, such as demodicosis or Demodex blepharitis, typically involves a combination of medical approaches depending on the severity and duration of the condition.

The first line of treatment will be an office-based procedure called Zest which targets eyelid hygiene to promote a healthy environment for the lids and lashes. Then at home maintenance will require specialized tea tree oil cleansers. The mites have a 4-6 week life cycle, so it’s important to use the appropriate tea tree oil products nightly for 6 to 8 weeks to ensure clearance of the mites.

For some patients, tea tree oil is used indefinitely for maintenance, especially in those who are prone to recurrent styes and/or have atrophy of their meibomomian glands.