For 10 of 13 patients with Demodex blepharitis in this study, two weeks of treatment with 1% 5-FU led to complete mite resolution.
For 10 of 13 patients with Demodex blepharitis in this study, two weeks of treatment with 1% 5-FU led to complete mite resolution. Photo: Cecelia Koetting, OD. Click image to enlarge.

Last year’s approval of the first prescription drop for Demodex blepharitis (Xdemvy, lotilaner ophthalmic solution 0.25%, Tarsus) has shaken up the treatment paradigm for this common condition, which traditionally involved non-targeted therapies such as tea tree oil and techniques to improve lid hygiene. Another agent being looked at as a potential treatment for ocular demodicosis is one you may already have in your clinic to treat ocular surface squamous neoplasia—topical 1% 5-fluorouracil (5-FU). Its potential application as a therapy for Demodex appears promising based on the recent results of a small study.

Included in the observational retrospective review were 13 eyes from 13 patients (ages 30 to 84 years) with conjunctival neoplastic lesions and concomitant Demodex lash infestation. All patients received topical 1% 5-FU eye drops in a cyclical fashion: one cycle of treatment comprised one week of eye drops, administered four times per day, followed by three weeks with no drop use. At each follow-up visit, patients underwent slit-lamp exams, and clinical photographs of the lash line were obtained. In a subset of patients, lashes were epilated bilaterally and microscopically analyzed for the presence of Demodex mites before and after treatment was initiated.

After two cycles of 5-FU, the researchers reported that all 13 patients had a marked reduction in cylindrical dandruff in the treated eye. Additionally, cylindrical dandruff completely resolved in 10 of 13 treated eyes vs. zero of 13 untreated eyes. In the six patients who received epilation, the lashes from the treated eye showed no Demodex, while persistent Demodex was seen in lashes from the fellow untreated eye.

“We found that 1% 5-FU treatment had a prolonged clinical effect of reducing Demodex infestation for up to 55 months,” the researchers wrote in their paper on the study, published recently in Cornea. “This finding prompts further investigation of the off-label use of topical 1% 5-FU for the treatment of Demodex blepharitis,” they concluded. Future studies with larger cohorts may also augment the significance of these findings.

Amer MM, Ho JW, Theotoka D, et al. Role of topical 5-fluorouracil in Demodex-associated blepharitis. Cornea. January 18, 2024. [Epub ahead of print].