Demodex colonization is a significantly more severe problem following either cataract surgery or postoperative topical steroid treatments, according to findings published in the American Journal of Ophthalmology. The microscopic mites are a common dry eye disease risk factor.
Researchers conducted a prospective study of 62 patients (mean age, 71.04 years) to determine the incidence of Demodex on the eyelashes of patients following cataract extraction surgery.
Surgeons removed several eyelashes from patients prior cataract surgery. The eyelashes were examined independently by the hospital laboratory for the presence of the Demodex mites, and the process was repeated 3 weeks postoperatively. Patients received the standard treatment of steroid drops alone for a period as individually required in the postoperative weeks.
The researchers observed Demodex colonization in 22.58% of samples before cataract surgery and in 32.26% after cataract surgery and topical postoperative steroid therapy (P =.014). This is significantly lower than some reports that show Demodex in 84% of the population in their sixties, and approximately 100% of those older than 70 years.
They note that, though patients occasionally report chronic irritation and epiphora following cataract surgery, little research exists regarding the relationship between cataract surgery and Demodex colonization. Moreover, the study cites the common clinical decision by cataract surgeons to refer these patients for oculoplastic consultation.
Rosacea, age, sun exposure, alcohol consumption, and immunosuppression are associated with an increased risk of Demodex infestation, the study authors report. Their findings demonstrate a definite association between cataract surgery and the population of Demodex mites on the eyelids. The researchers also report that future studies should focus on the relationship between steroid drops and Demodex blepharitis. The researchers highlighted that there is not necessarily a causal relationship between Demodex colonization and blepharitis, but that the association has clinical significance.
“We think that adjusting our approach to future post-operative evaluation of cataract patients by reducing topical steroid treatment to a minimum may be helpful,” the researchers explain. “In view of our findings, the diagnosis of Demodex blepharitis should be considered in patients complaining of chronic itching, grittiness or epiphora after cataract surgery.”
Study limitations include lack of a control group, and the lack of assessment of lashes from the nonoperated eye in participants.
Feldman I, Krausz J, Levinkron O, et al. Is demodex blepharitis connected with cataract surgery? Am J Ophthalmol. Published online May 29, 2023. doi:10.1016/j.ajo.2023.05.016