Is it possible that our eyelash follicles have been invaded by strange creatures? Not by body-snatchers, but quite likely by a tiny mite called Demodex, commonly associated with rosacea.
The royal we
Although we don’t like to think about it too much, our bodies are colonised by millions of other creatures – mostly bacteria. In fact, up to 9 tenths of the cells in our body are not human! Most people are familiar with the healthy gut flora (such as lactobacillus) that aid digestion and absorption of food. You may also be familiar with the normal bacteria that colonise our skin. All these microbes make up our biome. And one contributor is a tiny mite called Demodex.
What are Demodex mites?
These are parasitic mites that live in or near the hair follicles of mammals and generally do not cause symptoms. Humans have two species of demodex mites – one that lives in the hair follicle itself and a slightly small one that lives in the sebaceous glands connected to the hair follicle. (These later type are the ones that are seen in much higher than normal numbers in rosacea sufferers). As numbers increase, the mites can cause debris and oil to accumulate around the base of the eyelashes leading to blepharitis and ultimately, dry eye. Meibomian glands in the eyelids produce oil to maintain a healthy tear film. If the glands are blocked or the oil is contaminated, this can lead to evaporative dry eye. Demodex infestation (also called demodicosis) can also lead to hair loss, as seen in dogs with mange, and may even be associated with hair loss in humans.
Why is Demodicosis associated with ocular rosacea?
(What a tongue-twister!) It is not known if increased levels of Demodex in rosacea sufferers are a contributing cause or a result of the disease. Demodex like to eat the oil produced in the glands of the skin and eye lids. One theory is that increased oil production allows the mites to proliferate. Another theory is that mites and their waste products in the oil is what causes the inflammation response seen in facial and ocular rosacea. Whether cause or effect, this much is certain; if you suffer from ocular or facial rosacea, you are likely to have far higher numbers of demodex mites than normal, and these can contribute to the symptoms of ocular rosacea.
What is the best treatment for Demodex?
Most people are oblivious to these little guys and do not require any treatment. But if you are suffering from Meibomian gland dysfunction or the type of blepharitis that causes a build-up of crust around the base of the eyelashes, there are treatments available.
Blepharitis and Demodex
One of the most essential elements of controlling blepharitis is to keep the base of the eyelashes free from crusting. Lid scrubs are the mainstay of treatment for this condition. Physically removing the crusting is possible with home therapy using lid scrubs or for more established disease, an inhouse professional treatment called BlephEx may be more appropriate to eradiate the biofilm that builds up along the eyelid margins.
What’s the best product to use?
It is always best to use a proprietary lid hygiene product rather than messing around with homemade solutions of baby shampoo or bicarb (as these can be toxic to the delicate tissues of the eyelids). However, some lid wipes, such as Blephadex contain tea-tree oil, which is very effective against Demodex.