The prevalence and intensity of Demodex folliculorum and D. brevis (Acari: Demodicidae) in patients with ocular dandruff

Demodex mites (Acari) are micro-arthropods belonging to the family Demodicidae. Two species of these mites have been identified in humans: Demodex folliculorum and D. brevis. It is believed that these mites are important in the pathogenesis of eyelid symptoms such as cylindrical, sporadic and diffuse dandruff. The follicular epithelial cells and sebum are the main nutritional source of these mites. With the help of salivary enzymes and their mouthparts, they permeate the follicular epithelial cells. The follicular cell waste formed due to the feeding of the mites are moves towards the follicle surface, and as a result of it accumulates at the base of the lashes and form dandruff. This study was performed to determine the prevalence and intensity of Demodex spp. in patients with ocular dandruff. A total of 186 patients with ocular dandruff and 183 healthy controls were included in the study. Personal care and hygiene practices, demographic characteristics and skin biophysical parameters of these participants were recorded, and samples were taken from the facial areas (eyelash, eyebrow and cheek). In the study, Demodex positivity was detected in 90.9% of the cylindrical dandruff patients (mean 38.39) and 83.1% of the controls (mean 21.86). When the skin biophysical properties were taken into consideration, the density of Demodex was higher in participants with low moisture and temperature values and high pH values. On the other hand, Demodex positivity and density were increased with age of the participants. The most common ocular complaints were itching and foreign body sensation. Demodex mites were found to be very common and intense in the patients with ocular dandruff. Accordingly, Demodex mites should be taken in to consideration during the clinical evaluation and treatment of these patients.