Association Of Demodexfolliculorum Infestation With Meibomian Gland Dysfunction Signs And Tear Matrix Metalloproteinase-9 Concentration

Purpose:To explore the prevalence of Demodex folliculorum in patients with meibomian gland dysfunction(MGD),and analyze the association of Demodex folliculorum infestation with MGD signs and tear matrix metalloproteinase-9(MMP-9)concentration.Methods:96 eyes of 96 patients with meibomian gland dysfunction(MGD)were enrolled in this study.Evaluation of ocular surface parameter including tear meniscus height(THM),non-invasive break-up time(NIBUT),redness score,meibomian gland loss by the Keratograph 5M(OCULUS,Wetzlar,Germany),collection of tear(2.2μL)before invasive operation test Using the slit-lamp to observe the eyelid margin,meibomian gland expressibility,meibomian gland secretion turbidity,and measurement of the corneal fluorescein staining score(CFS)after the instillation of fluorescein.Counting the density of Demodex folliculorum infestation by epilating 6 eyelashes(3 eyelashes from upper eyelid and 3 eyelashes from lower eyelid)each eye under slit-lamp.The immunoassay test was used to detect the concentration of MMP-9 in tears qualitatively,positive status means the activation of ocular surface inflammation.The Spearman correlations test was performed between Demodex count and ocular parameters.The multiple logistic regression model was used to predict the risk factors of the rise of tear MMP-9 concentration.Results:Among the 96 participants,Demodex folliculorum was found in 57 of 96 MGD patients(59.4%)and 39 patients(40.6%)were diagnosed as Demodex blepharitis.The risk for a mite infestation increases 3.6%with each year of age(OR=1.036,95%confidence interval:1.006 to 1.067,P=0.018).Compared with non-infection Demodex group,the Demodex blepharitis group had worse eyelid score,worse meibomian gland loss,worse meibomian gland expressibility,worse meibomian gland secretion turbidity and more serious MGD grade.76.9%of patients in Demodex blepharitis group had eyelashes with a cylindrical dandruff of the tip.The increase of load of Demodex folliculorum had an effect on the meibomian gland function and eyelid inflammation,according to the Spearman correlation analysis,the Demodex count was correlated with older age(R=0.214,P=0.036),higher eyelid score(R=0.396,P=0.001),worse meibomian gland loss(R=0.244,P=0.021)and worse meibomian gland secrete turbidity(R=0.262,P=0.010).The correlation between Demodex count and other ocular parameters were not significant(all P>0.05).Multivariate logistic regression demonstrated that Demodex count and the presence of anterior blepharitis were independently associated with tear MMP-9 status(all p<0.05).When the load of Demodex folliculorum is increased by one grade(from low-load mites to medium-load mites,or from medium-load mites to high-load mites),the risk of the increase of tear MMP-9 becomes 1.5 times(OR=1.514;95%confidence interval:1.012 to 2.266;P=0.044).Patients with anterior blepharitis showed a risk of 5 times(OR=4.925;95%confidence interval:1.083 to 22.401;P=0.039)for the increase of tear MMP-9 than patients without anterior blepharitis.Conclusion:Demodex folliculorum was found in 60%MGD patients by epilating eyelashes detection.The increasing of the load of Demodex folliculorum related to worse eyelid signs and worse meibomian gland dysfunction,and tended to activate the ocular surface inflammation mediated by MMP-9.The application of tear MMP-9 detection may be a new choice to assess ocular surface inflammation in Demodex infection patients.