Eyeworld

MARCH 2021 | EYEWORLD | 89 C 1,2-octanediol. When used over a 4-week peri- od, this has been shown to decrease Demodex infestation. He also mentioned 1% ivermectin and 1% mercury oxide as having acaricidal activity. Hypochlorous acid (Avenova, NovaBay Pharma- ceuticals) has minimal activity against Demodex species. 2 Recalcitrant cases of Demodex infestation can be offered mechanical debridement using rotary tip devices such as the BlephEx device and a similar technology by Myco Company, Dr. de Luise said. As more treatment options become avail- able, Dr. Perry said he thinks some may start treating just based on cylindrical dandruff. If you can keep the follicles and lashes clean, the Demodex usually won't go into the lash follicle, he said. Regular lid hygiene can help with this, including using warm saltwater soaks, BlephEx, and agents like ivermectin. He noted that tea tree oil is effective. It's lethal to Demodex, but it can also be toxic, so it's important to exercise caution when using this option. "Some practitioners dilute commercially available tea tree oil with macadamia nut or walnut oil to decrease patient discomfort and toxicity to the ocular surface while maintaining efficacy in eradicating the mites," Dr. de Luise said. "Caution must be taken in those patients with nut allergies." Scheffer Tseng, MD, PhD, has done research looking at effectiveness of tea tree oil in treating Demodex but said that tea tree oil alone can be be pathognomonic for Demodex blepharitis, according to Gao et al.," 1 Dr. Yeu said. Dr. Perry said confocal microscopy may also be helpful, as it can identify Demodex in the follicle without pulling out the lash. But many physicians don't have this technology available. Dr. de Luise agreed that in vivo confocal laser scanning microscopy is a more accurate method to confirm a diagnosis. "It allows for a noninvasive magnified view of the affected folli- cles and is a more sensitive tool compared to slit lamp examination of epilated eyelash samples," he said. Dr. de Luise added that Demodex mites cause ocular inflammation by direct mecha- nism, as well as indirectly. "These mites have no excretory organs; their undigested material is regurgitated and combines with eyelid epithelial cells, keratin, and eggs to form the bulk of the cylindrical lash deposits said to be pathogno- monic of Demodex infestation," he said. "These deposits are clinically observable as collarettes. They contain inflammatory proteases and li- pases, which cause symptoms of irritation." Demodex can also cause inflammation by an indirect mechanism. "Their hindguts contain bacteria (Bacillus oleronius), which can activate the host's immune response," he said. "Even in their death, these mites may elicit an inflam- matory response by releasing bacterial antigens that trigger the host's inflammatory cascade." Treatment When treating, Dr. de Luise said that the overar- ching goal with Demodex infestation is to reduce eyelid margin mite populations, which in turn reduces ocular surface inflammation. Demodex does not respond to hot compresses or antibiot- ic-steroid ointment, he said. Dr. Yeu noted that there is not currently an FDA-approved therapy. She mentioned the use of scrubs, wipes, and other lid hygiene prod- ucts, particularly those containing tea tree oil but stressed the potential toxicity. Her choice of treatment will vary from patient to patient, and she may choose to be more aggressive for surgical patients. Dr. de Luise said an over-the-counter strate- gy for management is OCuSOFT Lid Scrub Plus (OCuSOFT), which contains a 0.5% solution of Six adult Demodex folliculorum on an eyelash Source: Henry Perry, MD References 1. Gao YY, et al. High prevalence of Demodex in eyelashes with cylindrical dandruff. Invest Oph- thalmol Vis Sci. 2005;46:3089– 3094. 2. Kabat AG. In vitro democidal activity of commercial lid hy- giene products. Clin Ophthalmol. 2019:13:1493–1497. 3. Cheng AM, et al. Recent advances on ocular Demodex in- festation. Curr Opin Ophthalmol. 2015;26:295–300. 4. Chen D, et al. Effects of ter- pinen-4-ol on meibomian gland epithelial cells in vitro. Cornea. 2020;39:1541–1546. continued on page 90

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