LAUSR

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. The most commonly reported symptoms before treatment were the presence of discharge (89.4%) and itching (83%); the most severe symptom at baseline was itching (Table 1). After treatment, itching was still the most commonly reported and most severe symptom. Significant improvements in itching, FBS, discharge, dryness, and lid margin crusting were noted (P= 0.03, 0.00, 0.00, 0.02, and 0.04, respectively) (Table 1). The Demodex count per lash significantly decreased from 1.24 to 0.69 mites per lash after treatment (P= 0.00) (Table 1). Total lid margin score, meibomian gland plugging and thickening were also significantly improved (P= 0.00, 0.00, 0.01, respectively; Table 1). TBUT increased significantly after treatment (P= 0.02). Multiple regression with adjustment to age and sex found that TTO treatment significantly improved itching (P= 0.00), FBS (P= 0.00), discharge (P= 0.02), and lash dandruff (P= 0.04) and this improvement was correlated with a decrease of about 0.63 Demodex per lash (P= 0.01) (Table 2). TBUT and meibomian gland plugging were also significantly improved by TTO treatment (P= 0.02 and P= 0.01, respectively) (Table 2). Treatment with in office 50% tea tree oil (TTO) and 5% TTO bid at home for one month proved to be effective in significantly lowering the mite/lash count. We also found that a change of 0.63 mites/ lash was critical in inducing improved symptoms and signs. We therefore propose that a change of about 1 mite/lash may be a clinical standard for improvement. Treatment of Demodex should require both the patient’s and clinician’s longterm dedication and persistence to keep Demodex count/ lash down. We hope this finding may help clinicians in educating the patients and setting a realistic goal of decreasing Demodex count per lash instead of aiming for total extermination. * Elizabeth P. Shen [email protected]