Demodex infestation is strongly associated with meibomian gland disease (MGD) and correlates with significantly worse meibomian gland function, structure, and lid margin abnormalities compared with patients without Demodex infestation.1
The review, conducted by Mile Brujic, OD, FAAO, owner of Premier Vision Group, and colleagues, evaluated 22 studies identified through a comprehensive search of MEDLINE and Embase and found the 2 conditions to be frequently comorbid, concluding that routine assessment for both Demodex blepharitis (DB) and MGD is warranted to optimize patient management. The data were presented at the 2026 Optometry’s Meeting of the American Optometric Association, held from June 17-20, in Phoenix, Arizona.
Demodex blepharitis is an eyelid margin disease caused by overgrowth of Demodex mites and characterized by collarettes, the pathognomonic sign of the condition, with global prevalence reported between 58% and 66.5% when defined by the presence of at least 1 collarette.1,2 MGD is a chronic, diffuse abnormality of the meibomian glands characterized by terminal duct obstruction and qualitative or quantitative changes in gland secretion. Demodex mite infestation may contribute to meibomian gland damage through mechanical obstruction, bacterial translocation, and inflammatory responses, though the association between Demodex infestation and MGD had remained incompletely characterized prior to this review.
Key Takeaways for Optometrists
- Patients presenting with MGD should be evaluated for Demodex infestation, and vice versa, given the consistently high comorbidity rates found across this body of evidence—MGD prevalence of 92% to 99% in symptomatic DB patients and Demodex present in at least half of MGD patients across 11 of 12 reviewed studies.
- Collarettes remain the pathognomonic sign for Demodex blepharitis; routine slit lamp examination of the lash line for collarettes should be considered standard practice in patients presenting with lid margin disease or MGD symptoms.
- Demodex-infested patients showed measurably worse meibomian gland structure (dropout, atrophy) and function (meibum quality) than non-infested patients across the majority of studies reviewed, suggesting Demodex burden may be a meaningful driver of MGD severity rather than simply a coincidental finding.
- Given the funding source—Tarsus Pharmaceuticals, a manufacturer of an FDA-approved Demodex blepharitis treatment—consider this context when evaluating the review’s framing and conclusions, while still weighing the underlying prevalence data presented.
Systematic review methodology and Demodex–MGD prevalence findings
The systematic search identified 520 records from PubMed (309) and Embase (211); after removal of duplicates and exclusion of studies not meeting population, design, or outcome criteria, 22 studies were included in the final analysis, supplemented by 1 additional study identified through bibliographic review.1 Studies were included if they reported MGD-related outcomes stratified by the presence or absence of Demodex infestation in patients recruited from eye care clinics; interventional studies were excluded.
In symptomatic patients with Demodex infestation or collarette grade 2 or greater, MGD prevalence was consistently high across studies, ranging from 92% to 99%.1 Across 11 of 12 studies reporting Demodex prevalence in MGD patients, Demodex infestation was present in at least 50% of patients with MGD, with individual study prevalence ranging from 45% to 89%.
Meibomian gland structure, function, and lid margin findings in Demodex-infested patients
Patients with Demodex infestation showed significantly higher (worse) meibum quality scores compared with patients without Demodex infestation in 6 of 8 studies reporting this outcome, indicating poorer meibum quality in infested patients.1 Patients with Demodex infestation also exhibited significantly greater meibomian gland dropout and atrophy compared with those without infestation in 5 of 6 studies evaluating this outcome.
Lid margin abnormality scores were significantly worse in Demodex-infested patients compared with controls in all 3 studies assessing this outcome.1 Demodex infestation was also associated with worse meibomian gland orifice obstruction, with infested patients showing significantly greater plugging of meibomian gland orifices and significantly smaller orifice area compared with those without Demodex infestation. High mite burden was reported among patients with plugged orifices; in 1 study, patients with Demodex infestation had a significantly lower meibomian gland orifice area compared with those without infestation (P <.001), and in another, 85% of patients with plugged meibomian gland orifices had 3 or more mean mite counts.
“Demodex infestation and MGD are often comorbid disease conditions,” the study authors concluded.1 “Demodex infestation is strongly associated with MGD, worse MGD severity, with affected patients demonstrating significantly worse meibomian gland function and structure and lid margin abnormalities. The findings underscore the importance of routine assessment for both DB and MGD to optimize patient management.”
References
Brujic M, Koetting C, Yeu E, Gaddie IB. Systematic review of the association between Demodex blepharitis and meibomian gland disease. Presented at: AOA 2026; June 17-20; Phoenix, AZ. Poster #23.
Trattler W, Karpecki P, Rapoport Y, et al. The prevalence of Demodex blepharitis in US eye care clinic patients: a population-based study. Clin Ophthalmol. 2022;16:1153-1164. doi:10.2147/OPTH.S354692
