Demodex Folliculorum is an ectoparasite which belongs to the class Arachnida (sub class: Acari). It can befound on the surface of the human body and is mostly found on the face, cheeks, forehead,nose and eyelids. Demodex often hide in the deep ducts of the sebaceous glands since active sebum excretions provide a favorable habitat for breeding and
nourishment. Signs of Demodex infestation include cylindrical dandruff, disorders of the eyelashes, lid margin inflammation, meibomian gland dysfunction, blepharoconjunctivitis and blepharokeratitis. Colonization of Demodex increases with age and reaches 100% by the age of 70. Demodex causes ocular itching, foreign body sensation, crusting and redness of the lid margin, and blurry vision. Suspicions of a Demodex infestation should be aroused by the loss of lashes and/or cylindrical dandruff around the base of the eyelashes during a slit lamp
evaluation. Examination of eyelashes under a microscope will confirm the presence of the Demodex mites.
Associated risk factors:
There are a large number of risk factors that may be associated with an increased infestationwith Demodex. Several reports have described the relationship between the rates of Demodex infestation and gender, but this topic remains controversial.
- Stress and emotion
- Climate: (warmth, humidity, sun and wind)
- Drinks and food:
- Coffee and tea
- Hot liquids, spicy food (e.g. chili, curry, pepper)
- Perfume, after shave.
- Peeling products
- Soap & Sun oil.
- Sinus and allergic conditions (e.g. the bacillus Oleronius)
Poor ocular hygiene in combination with increasing age may also be associated with an increase in Demodex count as a result of blocked orifices which prevent normal sebum secretion resulting in increased infestation.Treatment with topical steroids particularly long term use of these drugs may also result in an increase in the number of Demodex.There are some disorders of the eyelids, such as infections of the glands, dermatitis and psoriasis that need to be treated with corticosteroids, this aggravates Demodex but it sometimes is entirely impossible to treat two problems present at the same time.
Detection of Demodex Folliculorum
The detection rate of Demodex can be affected by many factors including checkpoint, area, daytime and times of examination. The use of make-up seems to reduce the likelihood of Demodex carriage in young adults. Nevertheless, it is observed a higher prevalence of Demodex mites in (older) women who used makeup, probably due the blockage of the meibomian orifices by moisture eye makeup but also due to hormonal alterations allowing the mites to reproduce at a higher rate. On the other hand Demodex density is related to age also older people uses more heavy make-up and creams, on regular basis, that make them more susceptible for Demodex Folliculorum.
Signs of Demodex Folliculorum
- Bilateral crusting and redness of the lid margins
- Lashes with dandruff
- Meibomian gland disease
- Swollen eyelids/blepharitis
- Conjunctival inflammation
- Corneal vascularisation
- Superficial opacities
- Nodular scaring
Facial skin manifestations:
- Itchy eyebrows, scalp and face
- Oilier skin than normal
- Enlarged facial pores
- Acne, cysts, and pustules
- Rosacea or facial flushing
- Hair loss (madarosis)
- Swollen nose
Symptoms of Demodex Folliculorum
The main symptoms of infestation are tickling and itching, crawling sensation on the face and in the scalp in the evening, burning, foreign body sensation, crusting and redness of the lid margin, blurry vision and failed response to dry eye treatments and blepharitis. Itching during the night and early morning on the lower nose, eyebrows and eyelashes and irritation is common with these mites because of their aversion to light. Demodex mites are active at night and come out onto the surface to mate and to lay their eggs on the lashes. They subsequently crawl back into the follicle in the morning, causing the patient to itch. What makes the diagnosis of Demodex difficult is that some patients will have “a lot of Demodex” without symptoms . All of these conditions are typically bilateral and chronic or relapsing, however unilateral demodicosis has been observed by Pallota (1998). Also, Shelley et al.(1989) described a case report of unilateral Rosacea with Demodex Folliculorum, after treatment with sunscreens and corticosteroids.
Demodex Folliculorum Treatment:
Several options are available for the treatment of Demodex Folliculorum. These include treatment with topical and systemic anti- inflammatory and antibacterial medications, mercurial ointment, sulphur ointment, camphorated oil, crotamiton, antibiotics, as well as anti mycotic drugs. Moreover ,a good response has been observed after oral application of ivermectin along with topical application of permethrin cream. As a topical treatment, tea tree oil is the preferred medication in combination with lid hygiene as evidence shows that it reduces the numbers of Demodex, is safe and has minimal side effects. It is also the only treatment that an Optometrist would be able to provide within the
remit of their practice.
Tea tree oil
Demodex is susceptible to tea tree oil . Tea tree oil is a natural oil distilled from the leaf of Melaleuca alternifolia. At home, a twice daily lid scrub with 5 % tea tree oil is followed by a massage of the eyelids in order to resolve the ocular Demodex infestation. After one month the home treatment is performed once a day. If the routine is not followed properly cylindrical dandruff returns within 1 week.
The management involved two steps:
- Massage of the eye lid margins at the root of the eye lashes during closed eyes.
- Massage of the lower eye lid margin separately.
Lid warming + massage
It is found a strong positive relation between ocular surface comfort and Demodex counts despite age. They concluded that good eyelid hygiene decreases the prevalence of Demodex and helps to improve ocular discomfort in all ages. Eye lid cleaning procedures and a warm compress and vertical eyelid massage works to both melt the thick wax in the meibum and loosen any debris on the eyelid margin and eyelashes. There are several devices which can be used to warm the eye lids. The success of this treatment appears to be multifactorial and includes thickening and stabilization of the meibomian lipid layer as well as the reducing bacterial colonization, which has been proven to be effective in diminishing the symptoms.
Even though there is no special diet to prevent Demodex, there are factors that may change the environment to encourage mites’ proliferation for example sunlight exposure and abrupt changes in temperature.Supplementing omega-3 fatty acids encourages the production of anti-inflammatory prostaglandins and modifies the composition of meibomian lipids. The results demonstrated an improvement in their overall Ocular Surface Disease Index score, tear break-up time, and meibum score. They concluded that when the intake of unprocessed oils, cold-water fish and natural oils is low, omega-3 fatty acids can help to improve the tear film.
Demodex Folliculorum infestation can be responsible for ocular surface inflammation,meibomian gland dysfunction and blepharitis. In addition, Treatment of Demodex in general takes a few months. Apart from other treatment options described in this dissertation; lid scrub with tea tree oil is an effective treatment to eradicate ocular Demodex. It improves visual acuity and leads to a more stable tear film layer.