Demodex Blepharitis

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Findings

  • Chronic blepharitis without improvement on standard treatment, collarettes (cylindrical dandruff at the root of eyelashes)

Management

  • Eyelid hygiene with NaviBlef or TEBO Lip 1-2x/d for 2 weeks or longer if chronic, alternatively Blephademodex pads 1-2x/d for 4 weeks
  • alternatively Tea tree oil 5% (CAVE: severe burning, educate patients about this side effect!) or metronidazole gel 0.75% or Metrogel 2% 2-3x/d
  • Systemic therapy in case of pronounced findings:
    • Metronidazole (Flagyl) as a short course (off-label): single 2g dose orally (= 4 tablets of 500 mg) in the evening; weak evidence for Demodex
    • Alternative: Metronidazole 2x500mg/d for 10 days
      • Caution: No alcohol (disulfiram-like reaction); enhances oral anticoagulants (bleeding risk)!
    • Alternative: Azithromycin 250 mg twice daily for 3 days (off-label), then a 7-day break; repeat the cycle 4 times
    • Alternative: Ivermectin (Subvectin 3mg tbl.) 200µg/kg orally as a single dose
      • In Switzerland Subvectin 3 mg is licensed (scabies, from 15 kg) but not on the Specialities list, so not reimbursed; alternatively a compounded preparation)
      • Contraindication: Pregnancy + lactation (teratogenic), children <5y or <15kg, therapy with inhibitors of P-glycoprotein
    • USA: lotilaner 0.25% eye drops (Xdemvy) – FDA-approved for demodex blepharitis since 2023, not (yet) licensed in the EU or Switzerland

Work-up

  • Slit lamp: collarettes visible? Highly correlated with Demodex blepharitis!
    • have patients close their eyes, examine the lash follicles on the upper lid
    • epilation of eyelashes not mandatory
  • Detection of Demodex under the microscope
    • epilate 2-4 eyelashes, placing them on a glass slide, put 1 drop of 0.9% NaCl and add fluorescein on top
    • cover with a cover slip, leave under the microscope with the light switched on for approx. 10–20 min (heat activates Demodex, causing them to move)
    • examine them under the microscope (20-40x magnification) for the presence of mites in the area of collarettes

Sources

  • EyeWiki Demodex
  • crstoday.com – Collarettes Equal Demodex Blepharitis
  • The Wills Eye Manual: Office and Emergency Room Diagnosis and Treatment of Eye Disease; Kalla A. Gervasio MD, Travis J. Peck MD et al.; Wolters Kluwer; 8th edition (2021)
  • Kanski’s Clinical Ophthalmology: A Systematic Approach; John F. Salmon; Elsevier; 10th edition (2024)