Comorbidity of Ocular and Facial Demodicosis.

PURPOSE: To determine the association between ocular and facial demodicosis, and the effect of facial treatment on ocular demodicosis.

DESIGN: Prospective clinical cohort study.

METHODS: Ocular demodicosis outpatients from a tertiary medical center were enrolled from April to December 2020. The diagnosis was based on epilation of four eyelashes from each upper eyelid. High ocular Demodex load (ODL) was defined as ≥8 mites per eye. Facial infestation was assessed by direct microscopic examination, with facial Demodex overgrowth (FDO) defined as a density >5 mites/cm2 . All patients were prescribed three months of ocular treatment, and FDO patients received dermatologic treatment.

RESULTS: Eighty-nine patients were enrolled. Among those that completed the treatment course, 39 presented high ODL. Lower cylindrical sleeve counts were found in low ODL patients (low ODL vs. high ODL: 8 vs. 14, P = 0.009). FDO was less prevalent in this group (49% vs. 77%, P = 0.012). The Ocular Surface Disease Index score decreased in patients without FDO (20.0 ± 17.1 to 14.0 ± 16.6, P = 0.027) after three months of topical tea tree oil treatment. Topical ivermectin treatment on the facial skin provided a higher ocular Demodex eradication rate in FDO patients (76% vs. 16%, P < 0.001).

CONCLUSION: Concurrence of ocular and facial demodicosis is common, especially in cases of severe ocular demodicosis. While ocular treatment alone is effective for patients with ocular demodicosis only, co-treatment with topical ivermectin on the facial skin enhances ocular Demodex eradication in patients with comorbid facial Demodex overgrowth.