Demodex infestation by Demodex folliculorum or Demodex brevis is an often under-diagnosed cause of chronic blepharitis associated with dry eyes, corneal infiltrates, neovascularizations, and corneal scars [1, 2]. Previous reports have mostly focused on the total Demodex count inducing clinical symptoms and signs [2, 3]. However, the number of lashes epilated is highly variable between each study making a direct comparison or setting a clinical standard for the pathogenic number of mites difficult. In this article, the Demodex mite count per lash (mites/lash) instead of total mite count will be used to correlate the effect of tea tree oil treatment (TTO) with clinical improvement in symptoms and signs.

A total of 47 patients (94 eyes; 21.3% male/78.7% female, mean age: 65.97 ± 12.62 years) were treated with 50% TTO under topical anaesthesia in clinic and also instructed to use 5% TTO twice a day at home. The patients were followed every 2 weeks for 1 month. At each visit, three lashes were epilated from each eye and Demodex count per lash was calculated by observation under a light microscope. Lid margin abnormalities were graded following Arita et al. meibomian gland dysfunction (MGD)/lid margin grading scale [4]. Tear film break-up time (TBUT) and basal Schirmer test were performed. Symptoms were scored on a five-point scale (0 – none, 5 – most severe) during each visit.

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