In vitro demodicidal activity of commercial lid hygiene products

Abstract

Purpose

Demodex folliculorum is a ubiquitous mite that can infest the eyelash follicles. Two commercial lid hygiene products have asserted their effectiveness in killing Demodex mites, yet there has never been a comparative trial between these two products. This study evaluated the demodicidal activity of 0.01% hypochlorous acid (HOCl) solution (Avenova; NovaBay Pharmaceuticals; Emeryville, CA) and 4% terpinen-4-ol (T4O) solution (Cliradex, Bio-Tissue; Miami, FL) in comparison to mineral oil (MO), a negative control.

Methods

Live Demodex mites were obtained from volunteers. Samples were immersed in 1–2 drops of test solution: 0.01% HOCl, 4% T4O, or 100% MO. Samples were observed under the microscope every 10 mins for up to 90 mins. Kill time was defined as the elapsed time between the addition of test solution and all cessation of movement of the body, legs, mouth and pedipalps for a minimum of 60 seconds.

Results

T4O demonstrated a mean kill time of 40±0.0 mins. HOCl had a mean kill time of 87.86±4.23 mins, with 79% of samples surviving the full 90 mins. In the MO group, all samples survived through the 90 min mark. Kill time was statistically significant in favor of T4O as compared to HOCl (p=0.0005). There was no statistically significant difference in kill time between HOCl and MO (p=0.25).

Conclusion

4% T4O effectively killed all adult mite samples within 40 mins of exposure. In contrast, the demodicidal activity of 0.01% HOCl was minimal, and comparatively similar to 100% MO.

Keywords:

• Demodex
• blepharitis
• lid hygiene
• tea tree oil
• terpinen-4-ol
• hypochlorous acid

Acknowledgments

The author wishes to thank Hosam Sheha, MD, PhD for his insights and assistance with the statistical analysis of this study. Financial support for this study was provided by TissueTech, Inc. This data set and its conclusions were originally presented as a poster at the Association for Research in Vision and Ophthalmology (ARVO) Annual Meeting 2018. The poster’s abstract was published in Investigative Ophthalmology and Visual Science, July 2018, Vol. 59, 905,  https://iovs.arvojournals.org/article.aspx?articleid=2693620.

Disclosure

Dr Alan G Kabat is a consultant for Bio-Tissue, Inc. Dr Alan G Kabat reports non-financial support from TissueTech, Inc., during the conduct of the study; personal fees from Avellino Labs, Bio-Tissue, Inc., Bruder Healthcare Company, Inc., Lacrivera, OCuSOFT, Inc., Shire, Sight Sciences, Sun Pharmaceuticals, Vmax Vision, Kala Pharmaceuticals, Inc., National Vision Administrators, LLC, Quidel, TearScience and EyeGate Pharma, outside the submitted work. The author reports no other conflicts of interest in this work.