Prevalence of Ocular Demodicosis in an Older Population and Its Association With Symptoms and Signs of Dry Eye

Cornea. 2021 Aug 1;40(8):995-1001. doi: 10.1097/ICO.0000000000002542.


Purpose: To evaluate associations between Demodex and its symptoms and ocular surface parameters in individuals with dry eye (DE).

Methods: A cross-sectional study of 119 individuals with DE symptoms or signs, grouped by the presence of ocular demodicosis, was performed. All individuals filled out questionnaires and underwent an ocular surface examination. Demographics, comorbidities, symptoms profiles, and ocular surface parameters were compared between the 2 groups. Multivariable regression analyses were used to determine which factors were associated with DE symptoms. Receiver operating curves analyses were performed to evaluate relationships between Demodex quantity and specific clinical phenotypes.

Results: Demodex was highly prevalent in our population (68.9%) with average counts of 4.2 ± 3.9. Individuals with and without Demodex had comparable demographics. Overall, symptoms profiles were similar between individuals with and without Demodex using the Dry Eye Questionnaire 5 and Ocular Surface Disease Index. Individuals with Demodex, however, were more likely to report itching (58.5% vs. 35.1%, P = 0.03), with increasing frequency in those with higher Demodex counts. Individuals with Demodex also had more severe eyelid abnormalities [cylindrical dandruff (CD) and lid vascularity] and a more unstable tear film but similar tear production and corneal staining when compared with individuals without Demodex. Neither Demodex nor ocular surface findings related to DE symptoms in multivariable analyses. Receiver operating curves analysis revealed Demodex counts ≥2 maximized sensitivity and specificity for both itching (64.7% and 59.0%, respectively) and CD (80.4% and 60.4%, respectively).

Conclusions: Demodex is highly prevalent in an older population with DE. Symptom of itching and CD were the findings most specific for Demodex.

MeSH terms

  • Age Factors
  • Aged
  • Animals
  • Blepharitis / complications
  • Blepharitis / epidemiology*
  • Blepharitis / parasitology
  • Cross-Sectional Studies
  • Dry Eye Syndromes / complications
  • Dry Eye Syndromes / diagnosis*
  • Eye Infections, Parasitic / complications
  • Eye Infections, Parasitic / epidemiology*
  • Eye Infections, Parasitic / parasitology
  • Eyelashes / parasitology*
  • Female
  • Florida / epidemiology
  • Humans
  • Male
  • Middle Aged
  • Mite Infestations / complications
  • Mite Infestations / epidemiology*
  • Mite Infestations / parasitology
  • Mites*
  • Prevalence