We have all seen the chronic blepharitis patient that has attempted
numerous unsuccessful treatment regimens and has visited numerous eye doctors
looking for some relief. Interestingly, the cause of their chronic blepharitis
might be secondary to Demodex infestation.
The Demodex mite is an eight-legged (an arachnid) ectoparasite (living
on the surface of the host) that can reside in our hair follicles and sebaceous
glands. Of the 65 described Demodex species, only Demodex brevis and
Demodex folliculorum are found on humans. Demodex is contracted and
spread by either direct contact or dust containing eggs.
|Keratinization mixed with lipids produces the classical clear
cylindrical dandruff that is associated with Demodex blepharitis.
Images: Gutierrez M
The adult D. brevis mite is about 0.2 mm long and tends to live
inside the lashs sebaceous glands and in meibomian glands. It has been
suggested that D. brevis can be associated with meibomian gland disease
and subsequent tear lipid deficiency. D. folliculorum buries itself face
down near the root of the eyelash and it is associated with anterior
D. folliculorum is longer, at about 0.4 mm in length, and has a
more slender, tapered body than D. brevis. D. folliculorum often live in
clusters, where D. brevis are more solitary.
Life cycle, survival of Demodex
The typical Demodex life cycle is usually 2 to 3 weeks. A female Demodex
mite lays 15 to 20 eggs inside the hair follicle near the sebaceous glands. The
eggs develop into larvae, which eventually become an adult eight-legged mite.
The adult male Demodex mite will leave the follicle in search of a mate, while
the adult female mite remains in the follicle. The mites are capable of walking
approximately 10 mm/h and tend to be more active in the dark.
It is thought that both D. folliculorum and D. brevis
consume epithelial cell cytoplasm by piercing through the cell membrane. D.
folliculorum infestation causes follicular hyperplasia with subsequent
increase in keratinization near the base of the eyelash. This keratinization
mixed with lipids produces the classical clear cylindrical dandruff that is
associated with Demodex blepharitis. This dandruff is thought to be a product
of the mites claws scrapping around the follicle.
Eyelashes infested with Demodex often are brittle and are easily
epilated. On about every tenth eyelash, one or more Demodex mites can be
detected even in healthy asymptomatic patients.
|Two Demodex attached to the hair follicle root.
Patients who suffer from Demodex infestation may complain of eyelid and
eyebrow itching (especially in the morning), madarosis, a burning sensation and
a foreign body sensation that seems to originate beneath their lids. Demodex
blepharitis is observed equally in males and females and is age related. A
study by Junemann showed that Demodex is found in 25% of 20-year-olds, 30% of
50-year-olds and 100% in patients older than 90 years.
Patient exam, diagnosis
During slit lamp evaluation, become suspicious of the possibility of
Demodex blepharitis if you notice cylindrical dandruff. Cylindrical dandruff is
a clear tubular cuff that is attached to the eyelid margin and encircles the
eyelash base. Some doctors feel that clinical evidence of cylindrical dandruff
is pathognomonic for D. folliculorum infestation and that the extent of
the infection is associated with the number of eyelashes containing the
|A single dead mite. Note the legs sticking straight
Definitive diagnosis of Demodex involves viewing an epilated eyelash
under the microscope. It is important to understand that the mite has to be
firmly attached to the eyelash when it is epilated for it to be seen. In all
probability, some of the mites will have remained in the follicle after
epilation. In fact, if you move the lash side to side, you can see the Demodex
tails protruding from the eyelash base with the slit lamp on high
When selecting a lash to epilate, look for those with cylindrical
dandruff, especially if the lash is discolored or brittle. A study by Gao and
colleagues showed that lashes with cylindrical dandruff were 10 times more
likely to contain Demodex mites.
Two views of multiple mites coming from a
collarette, and a single mite on the follicle.
Next grab the base of the lash and move it from side to side and then up
and down and pull slowly. I have found this produces a larger bulb
of tissue around the root with a greater number attached mites.
I then place the eyelash on the microscope slide and gently add a drop
of 0.25% fluorescein. I place a cover slip and view the specimen with low
magnification under the microscope. This will help detect a mite that was
loosely attached to the lash, but floated away.
The cylindrical dandruff cuff will sometimes remain attached to the lid
after epilation. Remove this with your forceps and add this to the microscope
slide, as these cuffs often contain Demodex.
|Multiple mites coming from a collarette.
Next, add 100% alcohol underneath the cover to help evaluate for
additional Demodex yield. The alcohol will soften the cuff and will stimulate
and irritate the Demodex inside and cause them to move out of the cuff for
Demodex blepharitis treatment goals include: eradicating the adult mites
and their offspring, prevention of further mating, avoiding re-infestation and
alleviating the patients symptoms. Understanding the mites life
cycle and habits will help us design a logical treatment plan.
There are a number of published treatment regimens that report good
results. My regimen is a modification of some of these.
First, therapy begins with educating the patient about their condition
and showing them photos of the Demodex mites living in their hair follicles.
Compliance is not an issue once the patient sees the crawling mites. I use a
digital microscope that can take both photographs and video.
Initial treatment involves an in-office lid scrub/débridement.
Start by instilling a drop or two of TetraVisc (tetracaine 0.5%,
Cynacon/OcuSoft) or other long-lasting anesthetic. Then thoroughly
débride the lashes and eyebrows with a cotton tip applicator soaked in
20% to 50% tea tree oil.
Tea tree oil also has excellent concentration-dependent Demodex-killing
properties. Keep in mind that the readily available 100% tea tree oil solution
is very irritating and, as such, should be diluted. One can prepare a mixture
of 50% tea tree oil by diluting the tea tree oil in either macadamia or walnut
For mild cases of cylindrical dandruff, I will often use a commercially
available tea tree oil, 20% Desert Essence (www.desertessence.com).
This irritates the mites and stimulates them to come out of the follicle.
Repeat this procedure in 10 minutes.
Next, apply an antibiotic/steroid ointment to help keep the mites from
moving and possibly suffocate them. The steroid also helps calm down the
inflammation secondary to the chemical and mechanical irritation of the
in-office treatment, in addition to suppressing the possible inflammatory
cascade associated with the decaying mites. The patient will return in 2 weeks
for repeat office treatment.
Send patients home with specific instructions. They should immediately
wash sheets and pillow cases in hot water and dry with the high
dryer setting and discard their pillows. They should not use makeup for at
least 1 week and discard all old makeup. Recommend using tea tree soap on their
face and consider tea tree hair shampoo as well. Make an appointment for the
patients spouse to have an evaluation, as they are frequently also
Ask the patient to purchase a supply of Ocusoft Plus Lid Scrub pads
(Cynacon/Ocusoft). They should thoroughly scrub the lash margins, then work the
eyelids and eyebrows. Do not rinse.
Allow the solution to dry, then apply a light film of antibiotic/steroid
combination ointment over the lashes. In the morning, lids should be scrubbed
again and rinsed well. The steroid/antibiotic ointment should be discontinued
in a week and substituted with a bland ophthalmic ointment. This regimen should
be continued for 3 more weeks (4 weeks total).
As a maintenance regimen, the patient should continue lid scrubs at
least twice a week indefinitely. A follow-up appointment should be scheduled
for 6 months. Mario Gutierrez, OD, FAAO
- Czepita D, Kuzna-Gryegiel W, Czepita M, Grobelny A. Demodex
folliculorum and Demodex brevis as a cause of chronic marginal
blepharitis. Annales Adadmiae Medicae Stetinesis.
- Gao Y, Di Pasuale MA, Elizondo A, Tseng SC. Clinical treatment of
ocular demodecosis by lid scrub with tea tree oil. Cornea.
- Gao Y, Di Pascuale MA, Li W, et al. In vitro and in vivo killing of
ocular Demodex by tea tree oil. Br J Ophthalmol.
- Gao Y, Di Pascuale MA, Li W, et al. High prevalence of ocular
Demodex in lashes with cylindrical dandruff. Invest Opthalmol Vis
- Junemann A. Demodex folliculorum in chronic blepharitis.
Available at http://www.onjoph.com/english/demodex.html. Accessed May 20,
- Kheirikhah A, Blanco G, Casas V, Tseng SC. Fluorescein dye improves
microscopic evaluation and counting of Demodex in blepharitis with cylindrical
dandruff. Cornea. 2007;26(6):697-700.
- Kheirkhah A, Casas V, Li W, Raju VK, Tseng SC. Cornea
manifestations of ocular Demodex infestation. Am J Ophthalmol.
- Lacey N, Kavanagh K, Tseng SC. Under the lash: Demodex mites in
human diseases. Biochem (Lond). 2009;31(4):2-6.
- Liu J, Sheha H, Tseng SC. Pathogenic role of Demodex mites in
blepharitis. Current Opinion in Allergy & Clinical Immunology.
- Mario Gutierrez, OD, FAAO, is the San Antonio administrator for
Vision Source. He can be reached at Vision Source-Alamo Heights, 5212 Broadway,
San Antonio, TX 78209; (210) 829-8083;
- Disclosures: Dr. Gutierrez has no direct financial interest in the
products mentioned in this article, nor is he a paid consultant for any
companies mentioned. He is an unpaid clinical advisor to Cynacon/OcuSoft.