Low prevalence of eyelid infestation by Demodex folliculorum in patients with primary open-angle glaucoma treated with prostaglandin analogues

Introduction: Primary open-angle glaucoma (POAG) shows an exponential growth related to age. Prostaglandin analogues are first-line drugs. As a side effect, they cause elongation, pigmentation and thickening of the eyelashes. Demodex are ectoparasites that live in the skin of humans and are associated to blepharitis. Their rate of infestation increases with age. Aim: Analyze and compare the prevalence of eyelid infestation by Demodex in patients with POAG who attend the clinic in a random manner, and who are receiving treatment with prostaglandin analogues. Methods: 110 eyes treated with prostaglandin analogues for POAG were included. An eyelash was removed to analyze it under the microscope and observe the presence of infestation. The results were compared with a group of patients with similar characteristics who did not use this drug. In addition, an in vitro study with one drop of different prostaglandin analogues on a slide of samples infested with Demodex was carried out to evaluate the direct chemical effect. Results: 36.4% of patients with POAG treated with prostaglandin analogues were infested with Demodex. The in vitro study showed the morphological changes that the mites suffered. Conclusions: Although the average age was high in the group of patients studied, a low prevalence of Demodex eyelid infestation was observed, unlike other series of patients of the same age who did not receive this medication and had a higher prevalence of infestation.