One of the most common causes of Blepharitis is the Demodex mite. The human skin carries several microscopic ectoparasites, with Demodex being one of the most common. While this is found in human skin very commonly, the quantity and rate of the swarm is directly proportional to age and is, thus, found mostly in those above the age of 60. While age is a factor for the density of Demodex, it is also high in those with skin conditions like rosacea. Several other skin conditions may also cause a high density, some of which are listed below:

• Facial pigmentation • Perioral Dermatitis • Basal Cell Carcinoma • Pityriasis Folliculorum • Bald scalp • Eruptions like Scabies • Demodicosis Gravis

Apart from these conditions, lack of hygiene may also be cause of the Blepharitis. While daily facial cleansing is a common habit, many pay little attention to the eye. It often does not receive the thorough cleansing the rest of the face does. This is what encourages the spreading of Demodex to the eye once it initiates in other parts of the face. Eventually, it causes the inflammation of the eyes in the form of Blepharitis. The mites may be present on the skin, but over populations of the mites cause conditions such as Blepharitis. Up to twenty five mites can live in the follicle of one eyelash.

Demodex mites have been discovered to have two different types. Demodex Folliculorum is one of these, which usually occurs in the lash follicle on the eyelid. The other is D. Brevis, which is found on the inside and mostly effects the meibomian glands that are responsible for lubricating the eye. Regardless of their presence, they tend to feed on glandular and follicular cells, which is the main reason they end up causing eyelid damage. The eyes must, therefore, be kept clean and hygienic so as to avoid the unwanted spread of the infestation in the first place.

Despite the problems that Demodex causes, its clinical role in Blepharitis is a much debated issue. People are unsure if the Demodex mites arrive first and then cause the problems, or if they arrive once the problems begin. There are few however, that would deny that once the Demodex mites begin to multiply in excess, that they cause a lot of problems. This is why when Demodex Blepharitis occurs as a symptom of other eye diseases, both internal and external. In many cases the effects of Demodex mites are ignored. However, research has shown the pathogenic life of Demodex mites is a large factor in Blepharitis, leading to inflammation of the eye.

Demodex mites usually have a lifecycle ranging from 14-18 days, though females may live an additional 5 days. The range runs from the time they hatch to their adult stage and subsequent death. Their mating causes serious eyelid damage, which is why it is important to use things such as tea tree oil and neem oil to prevent them causing too much damage. Direct transmission should of undiluted oil is not a good idea, as it can be very strong if it is not correctly portioned out into a usable lotion or cream.