Demodex Blepharitis

Demodex blepharitis is lid margin inflammation caused by overgrowth of Demodex folliculorum (in lash follicles) and Demodex brevis (in meibomian glands). Mite waste, bacteria carried by the mites and a hypersensitivity response cause the inflammation.

• Prevalence rises with age; more than 80 percent of older people carry mites.
• Rosacea, seborrhoeic dermatitis, immunosuppression and contact lens wear are risk factors.
• It often coexists with meibomian gland dysfunction.

Itching of the lid margins, worse in the morning, burning, foreign body sensation, redness, crusting and lash loss.

• Cylindrical dandruff (collarettes) wrapping the base of the lashes is characteristic.
• Differential diagnosis: staphylococcal blepharitis, seborrhoeic blepharitis, posterior blepharitis, allergic blepharitis, ocular rosacea, trichiasis, lice infestation, sebaceous carcinoma.
• Complications: chalazion, recurrent styes, lash loss, trichiasis, conjunctivitis, corneal inflammation and neovascularisation, dry eye.

Clinical diagnosis with epilation and microscopy.

• Slit lamp examination for collarettes; epilation of four lashes from each lid and examination of the lash under a light microscope in a drop of mineral oil, with 3 or more mites per lash being significant.
• Screen for rosacea and seborrhoeic dermatitis.
• Biopsy only for atypical or unilateral disease.

Reduce the mite load and control inflammation.

• Supportive: daily lid scrubs with tea tree oil 5 percent lid wipes or foam for 6 weeks (two mite life cycles), hot water washing of pillowcases and towels, avoid sharing eye make up, treat facial rosacea and seborrhoea.
• Pharmacological: tea tree oil 5 percent scrubs twice daily for 4 to 6 weeks; lotilaner 0.25 percent eye drops twice daily for 6 weeks where available; ivermectin 1 percent cream applied to the lid margin and face daily for 4 weeks; oral ivermectin 200 micrograms/kg as two doses a week apart; metronidazole 2 percent gel applied to the lid margin twice daily for 6 weeks; oral doxycycline 100 mg daily for 6 to 12 weeks for associated meibomian gland disease; preservative free lubricants.
• Procedures: lash epilation; in office lid debridement and tea tree oil treatment in resistant cases.
• Special groups: pregnancy, avoid oral ivermectin and doxycycline and use topical tea tree oil; children, treat lids gently and avoid doxycycline under 8 years; immunosuppressed, longer treatment.
• Red flags: loss of vision, corneal ulcer, lid mass, unilateral lash loss, painful red eye.
• Follow-up: review at 6 weeks; maintenance weekly lid scrubs prevent recurrence.