Occurrence of Demodex species in patients with blepharitis and in healthy individuals: a 10-year observational study

Abstract

Purpose: Two Demodex species (eyelash mites)-D. folliculorum and D brevis-are believed to be associated with human skin and eye diseases. However, the clinical significance of infection with Demodex species remains controversial.

Study design: The aim of this study was to estimate the prevalence of ocular demodicosis in patients with blepharitis as compared with the prevalence in the healthy population in Poland.

Methods: This case-control prospective study was carried out from 2007 to 2016. The enrolled patients (668) were divided into 2 groups: the study group, comprising 553 patients with blepharitis (349 women and 204 men, aged 17-88 years), and the control group, comprising 115 healthy volunteers without a history of ocular pathologies (78 women and 37 men, aged 17-88 years). A sample of 10 eyelashes was taken aseptically from each eye of the examined person and later studied under a light microscope.

Results: Demodex species were found in 62.4% (345/544) of the patients in the study group and in 24.3% (28/100) of the controls (P = .001, OR = 0.006). The overall prevalence was 55.8% (373/668) in all the examined participants. The presence of Demodex infection increased with age in both groups. No association of Demodex infection with gender was found (119/204 vs 226/349; P > .05, OR 1.086). A high mean number of mites was present more frequently in patients aged older than 50 years and in those who complained especially about itching (P < .05).

Conclusion: The prevalence of ocular demodicosis is significantly correlated with blepharitis and increases with age.

Keywords: Blepharitis; Demodex; Ocular demodicosis.