) in both eyes and the appearance of D. folliculorum tails (Fig. 5).
Patient 3 Discussion
Demodex avoids light, and it is unusual to see the mites under a biomicroscope.11 Demodex mites position themselves with their heads upside down in the deeper parts of the follicle. The elongated bodies protrude with their tails (opisthosoma) from the follicle in groups of three to five mites.34,35 Infrequently, the tails can be seen under the bright illumination of a biomicroscope. The tails have been described as cream-colored tails protruding from the lid margin like fine bristles.11,22 Because of their photosensitivity, most of the mating and movement of the mite are believed to occur at night. Mating plays an important role in perpetuating Demodex infestation because of the limited life span of 1 to 2 weeks for the adults.1,12 Females are territorial; they remain in their respective follicles and wait for the nomadic males that travel over the surface of the skin from one follicle to another in search of females. After copulation, the female burrows back into the follicle near the opening of the pilosebaceous gland and lays her eggs.35 Larva and protonymph develop in the sebaceous gland. They are brought to the opening of follicle and mature into deutonymph. Deutonymph crawls onto skin surface and reenters a hair follicle to become an adult.3 All of this movement likely happens in the dark.
A 60-year-old white woman with a history of rosacea came in with complaints of eyelid swelling, redness, and loss of lashes. She is currently using oral antihistamines for a history of allergy. In the past 3 years, she was prescribed topical antihistamines and a combination of steroid and antibiotic for eyelid inflammation, with no success. Meibomian gland dysfunction was grade 2+ OU and conjunctival redness grade 1+ OU. Mites were present on epilated lashes under the microscope.
Patient 4 Discussion
In 1930, Ayers called attention to D. folliculorum as a causative agent of Pityriasis folliculorum and one type of acne rosacea.11 Since that time, several studies show an association between Demodex and rosacea.33,34,36–41 For years, skin biopsy was the definitive dermatological test for Demodex. One study performed skin biopsy on rosacea patients and normal subjects. Rosacea patients had an average of 12.8 mites per square centimeter of skin; significantly greater than 0.7 mites per square centimeter in normal subjects.40 A meta-analysis has added further support to the association. Zhao and colleagues41 performed a meta-analysis of 48 separate studies done in 10 different countries on 28,527 subjects. Rosacea patients are seven to eight times more likely to have Demodex infestation.41
There are two bacterial links that may explain the connection between Demodex and rosacea. Bacillus oleronius has also been detected inside the digestive tract of the mites.12 Li et al.19 looked at 59 rosacea patients and found a significant correlation among serum immunoreactivity to bacillus antigens, Demodex infestation, and facial rosacea.19,26 Their study confirms the presence of bacillus in both the gut of the mite and rosacea patients. The second bacterium implicated is Staphylococcus epidermis, which was found in the pustules of the rosacea patients, but not in healthy (rosacea-free) skin. The theory is that Demodex serves as a carrier of Staphylococcus to areas where the bacteria can proliferate on the host.26 Once Demodex mite infestation establishes in the face, it is likely to spread and flourish in the eyelid.3
A 53-year-old woman with moderate dry eye signs and symptoms has been taking topical steroid–antibiotic combination off and on for the past 2 years. She is also taking 4% cromolyn eyedrops four times a day. The patient has a history of allergies. Meibomian gland dysfunction grade 2 OU is present. Cylindrical dandruff, eyelid edema, greasy oily debris, and telangiectasia were present in both eyes. On epilation of lashes, a mite appeared on the lash (Figs. 6, 7).
Patient 5 Discussion
The appearance of an actual mite on the surface in Figs. 5 an