Demodex Blepharitis

By Dr. Khang Ta

Published March 16, 2025

Demodex blepharitis is a common but frequently underdiagnosed condition caused by an overabundance of Demodex mites – microscopic ectoparasites that inhabit human skin, particularly hair follicles and sebaceous glands. While typically part of the normal skin microbiota, an overpopulation of these mites can lead to inflammation and dysfunction within the eyelid structures.

SYMPTOMS:

Demodex blepharitis can present with the following symptoms:

  • Redness and inflammation of the eyelids.
  • Itchy or irritated eyes and eyelids.
  • A burning or stinging sensation in the eyes.
  • White flakes or crusts at the base of the eyelashes.
  • Misdirected eyelashes and/or eyelash loss.
  • A sensation of having something in the eye (foreign body sensation).
  • Light sensitivity (photophobia).
  • Intermittent blurred vision.
  • Watery eyes.

These symptoms can vary in severity and may mimic other ocular surface or eyelid disorders such as allergic conjunctivitis, viral conjunctivitis, or bacterial conjunctivitis.

RISK FACTORS

Risk factors for Demodex blepharitis include:

  • Age: Prevalence increases with age, particularly in individuals over 60.1
  • Skin Conditions: Rosacea and seborrheic dermatitis are strongly associated with Demodex overgrowth.2
  • Poor Lid Hygiene: Accumulation of debris and oils can encourage mite proliferation.3

AETIOLOGY AND PATHOPHYSIOLOGY

Two distinct species of Demodex are implicated in blepharitis: Demodex folliculorum and Demodex brevis. D. folliculorum predominantly affects the base of the eyelashes, leading to anterior blepharitis characterised by eyelid margin inflammation, lash follicle dysfunction, and the presence of collarettes (cylindrical dandruff).4 In contrast, D. brevis invades the meibomian glands, where it obstructs lipid secretion, leading to posterior blepharitis. This can result in meibomian gland dysfunction (MGD), destabilisation of the tear film, and associated keratoconjunctivitis.

An excessive proliferation of these mites can result in the following pathological changes:

  • Eyelid Margin Inflammation (Blepharitis): Characterised by erythema, oedema, and irritation of the lid margins.5
  • MGD: Obstruction and inflammation of the meibomian glands, disrupting lipid secretion essential for tear film stability.6
  • Ocular Surface Damage: Compromise of the tear film integrity, leading to tear film instability, evaporative dry eye, and secondary epithelial damage.7
  • Styes and Chalazia: Chronic inflammation and obstruction of the meibomian or Zeis glands, often associated with Demodex infestation, can predispose to the formation of styes (acute, painful infections) or chalazia (chronic, noninfectious gland blockages). These conditions manifest as localised eyelid swelling and may further exacerbate ocular surface irritation.8

DIAGNOSIS

Clinical tests for Demodex blepharitis include:9

  • Slit Lamp Examination: Identifies cylindrical dandruff at the base of eyelashes.
  • Microscopic Analysis: Confirms the presence of mites by examining eyelash samples.
  • Infrared Meibography: Assesses meibomian gland function.

MANAGEMENT AND TREATMENT

Treatment involves addressing the underlying mite infestation and associated inflammation:

  • Lid Hygiene: Regular cleaning with tea tree oil-based cleansers to reduce mite populations.
  • BlephExTM Procedure: A professional in-office treatment that uses a specialised device to exfoliate and clean the eyelid margins. This procedure effectively removes biofilm, debris, and bacterial toxins.10
  • Warm Compresses: Helps to unblock meibomian glands and improve tear quality.
  • Anti-inflammatory Treatments: Topical corticosteroids or cyclosporine for severe inflammation.

Demodex blepharitis is a chronic, self-perpetuating condition characterised by eyelid inflammation, MGD, and tear film instability. These interconnected processes create a cyclical cascade of ocular surface inflammation and discomfort, progressively worsening symptoms if untreated. Early diagnosis and targeted therapy are crucial to disrupting this cycle, reducing inflammation, and restoring ocular surface stability, ultimately enhancing patient outcomes and quality of life.

  1. Post CF, Juhlin E. Demodex folliculorum and blepharitis. Arch Dermatol. 1963;88:298–302.
  2. Li J, O’Reilly N, Sheha H, et al. Correlation between ocular Demodex infestation and serum immunoreactivity to bacillus proteins in patients with facial rosacea. Ophthalmology. 2010;117:870–877.
  3. Rhee, M. K., Yeu, E., Barnett, M., Rapuano, et al. (2023). Demodex Blepharitis: A Comprehensive Review of the Disease, Current Management, and Emerging Therapies. Eye and Contact Lens, 49(8), 311-318.
  4. Liu J, Sheha H, Tseng SC. Pathogenic role of Demodex mites in blepharitis. Curr Opin Allergy Clin Immunol. 2010 Oct;10(5):505-10.
  5. Nguyen, M., Buckmiller, M., Sundararajan, M., Taravati, P. (2025). Blepharitis Associated Disorders. In: Woreta, F.A., Singh, R.B. (eds) Cornea Casebook. Current Practices in Ophthalmology. Springer, Singapore.
  6. Amano, S., Shimazaki, J., Yokoi, N. et al. Meibomian Gland Dysfunction Clinical Practice Guidelines. Jpn J Ophthalmol 67, 448–539 (2023).
  7. Xia, Y., Zhang, Y., Du, Y. et al. Comprehensive dry eye therapy: overcoming ocular surface barrier and combating inflammation, oxidation, and mitochondrial damage. J Nanobiotechnol 22, 233 (2024).
  8. Schear MJ, Milman T, Steiner T, et al. The association of demodex with chalazia: A histopathologic study of the eyelid. Ophthalmic Plast Reconstr Surg 2016;32:275–278.
  9. Ta, K.. Demodex blepharitis: new understanding, novel approach. Pharma; 12, 14-15 (2015).  
  10. Charles G Connor, Christopher Choat, Srihari Narayanan, Kirsti Kyser, Bonnie Rosenberg, Daniel Mulder; Clinical Effectiveness of Lid Debridement with BlephEx Treatment. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):4440.