Increased frequency of Demodex blepharitis in rosacea and facial demodicosis patients

Background Rosacea is an inflammatory disease with 50% of ocular involvement rate. Primary demodicosis is an eruption caused by Demodex mites, and there is no data about the rate of ocular involvement in primary demodicosis. Aims In this cross-sectional study, it is aimed to reveal the frequency of Demodex blepharitis in rosacea and primary demodicosis patients. Methods In total, 58 rosacea, 33 primary demodicosis patients, and 31 healthy volunteers were included in the study. Four samples were obtained from eyelashes with a forceps and from facial skin by standardized skin surface biopsy. A positive result is described as detecting at least one Demodex mite on an eyelash or at five mites in the face. The patients were also examined by an ophthalmologist in terms of ocular involvement. Results Both rosacea and primary demodicosis patients had significantly more complaints like burning and stinging in the eyes compared to the control patients (P = .001). Primary demodicosis and papulopustular rosacea patients had the highest numbers of eyelash mites, respectively, and significantly a higher rate of blepharitis than the control group. Conclusion As a result, the Demodex count was significantly higher in the primary demodicosis and rosacea patients than the control group. We think that every Demodex-positive patients should be evaluated for also eyelash mites to prevent a possible chronic blepharitis.