Dry Eye Disease Associated with Demodex Mite Infection: Focus on Ocular Surface Characteristics by Non-invasive Testing

Purpose: The study is to evaluate the effect of demodex mite infection on the ocular surface characteristics changes of patients with dry eye disease (DED) using non-invasive instruments. Methods: 127 patients with DED and 52 normal control subjects were enrolled in this study. All DED patients were divided into demodex negative group and demodex positive group based on the result of the demodex mite infection under microscope. Non-invasive tear break-up time (NIBUT), tear meniscus height (TMH), ocular redness, meibomian gland secretions (MGS), morphology of palpebral margin, meibomian gland loss score (MGLS), and cornea fluorescence staining (CFS) were evaluated under oculus corneal topography and slit-lamp. Results: The demodex positive group showed longer NIBUT ( P =0.003), lower TMH( P =0.021), worse morphology of palpebral margin ( P ＜0.001) and worse MGS ( P =0.007) than demodex negative group. The score of ocular redness in patients with DED were higher than in the control group ( P ＜0.05). In demodex positive group, age had a positive correlation with the degree of palpebral margin morphological damage (r s =0.332 P ＜0.05) and a negative correlation with the severity of meibomian gland loss (r s =-0.345 P ＜0.05). Conclusion: A significant association between demodex mite infection and abnormal morphology of the palpebral margin, a lower meibomian gland quality, and lacrimal gland hyposecretion in patients with DED. Prompt recognition of the possible co-occurrence of demodex mite infection in patients with DED is crucial for optimal management and improved patient comfort and prognosis.