Prevalence of DEMODEX in blepharitis patients and its association with dry eye disease

To determine the prevalence of DEMODEX in patients with blepharitis, its clinical characteristics, as well as its association with systemic conditions, and the type and severity of dry eye disease (DED).

A cross-sectional, observational, and analytical study was conducted. 302 patients with signs of blepharitis were evaluated from December 2024 to April 2025 at a Mexican ophthalmology referral center.

The prevalence of DEMODEX was 49.3%, with significant differences between age groups, observing a higher prevalence with advanced ages: 39.7% in <60 years, and 49.3% in ≥60 years (χ² = 0.009). Type 2 diabetes (T2D) was associated with a significant risk of developing demodicosis (OR 2.456 (CI 1.457-4.141), p = <0.001). Regarding clinical characteristics, patients with DEMODEX had a higher presence of collarettes, a higher prevalence of mixed blepharitis (58.4%), and mixed dry eye disease (DED). Regarding tests for dry eye type and severity, there were only differences in the Van Bijsterveld score (χ² = 0.009), but not for the TBUT, Schirmer, or OSDI scores.

Ocular demodicosis has a high prevalence in our population; its presence is associated with age, with no differences by gender. T2D increases the likelihood of developing DEMODEX. The anatomical and functional alterations caused by this ocular infection can promote or worsen the symptoms and severity of DED.