Comparing the in vitro effects of MGO Manuka honey and tea tree oil on ocular Demodex viability.

Purpose: To compare the in vitro antiparasitic effects of MGO Manuka honey and tea tree oil against ocular Demodex.

Methods: Fifty-two viable Demodex mites were acquired from the epilated eyelashes of 9 participants with blepharitis and symptomatic dry eye. Viable mites were randomised to one of five treatment groups: cyclodextrin-complexed and uncomplexed Manuka Honey, 100% and 50% tea tree oil, and no treatment. Following treatment application, mite viability was assessed for 240 min, based on limb and body movement and/or the development of a crenated/translucent appearance. Kaplan-Meier survival analysis was then performed.

Results: The log-rank test demonstrated a significant treatment effect on the survival distribution of Demodex mites (p < 0.001). Bonferroni-corrected post-hoc pairwise analysis showed that all treatments except for uncomplexed honey effected lower survival probabilities than the untreated group (all p < 0.001). Among the four treatments, survival probabilities were lowest with 100% tea tree oil (all p < 0.001), and highest with uncomplexed honey (all p ≤ 0.001). No difference was observed between complexed honey and 50% tea tree oil (p = 0.81).

Conclusions: The in vitro efficacy of cyclodextrin-complexed Manuka honey was comparable with 50% tea tree oil, an established treatment for ocular Demodex. The findings support future clinical trials investigating the therapeutic effects of complexed honey in demodectic blepharitis patients.