Prevalence and treatment effects of Demodex species in eyelash follicles in patients with meibomian gland dysfunction

Abstract

Objective: To investigate the prevalence and treatment effects of Demodex species in eyelash follicles in patients with meibomian gland dysfunction (MGD). Methods: The MGD patients (MGD group) and normal subjects (control group) were collected from the Ophthalmology Clinic in PUMCH from July 2015 to December 2015. The symptom score of MGD patients was recorded. Eyelash sampling, Demodex counting, tear film break-up time (BUT), cornea fluorescein staining (Fl) and Schirmer test Ia (S Ⅰ aT) were measured for both groups. All the measurements were repeated after 4 weeks of meibomian function treatment for the MGD group. Symptom score, BUT, Fl and S ⅠaT were normally distributed and displayed as mean± standard deviation. Demodex counting was not normally distributed and displayed as median (interquartile range P25, P75). Results: Forty-four MGD patients (88 eyes) and 48 controls (96 eyes) were recruited. For the MGD and control groups, the number of Demodex was 3.5 (2, 7) and 0 (0, 7), respectively (Z =-4.912,P= 0.000). The percentage of Demodex infestation was 86.4% and 39.6%, respectively (χ(2)=35.957, P=0.000). The BUT was (3.57±2.09) s and (10.17±3.25) s, respectively (t=-5.154, P=0.000). The Fl was 2.73±1.23 and 0.85± 0.33, respectively (t=4.583, P=0.000). The SⅠaT was (8.75±5.61) s and (14.51±5.29) s, respectively (t=-2.278, P=0.028). The symptom score of the MGD group before and after treatment was 4.77 ± 3.01 and 2.79 ± 2.01, respectively (t=6.224, P=0.000). The BUT, Fl and number of Demodex of the MGD group after the treatment were (5.43±2.37)s, (1.91±0.66) and 2 (0, 3), respectively, and all had significant difference with the data before the treatment (BUT, t=-4.705, P=0.000. Fl, t =3.902, P =0.000. number of Demodex, Z=-4.623, P =0.000). The S Ⅰ aT of the MGD group after the treatment was 8.86 ± 6.76, with no significant difference with the data before the treatment (t=-0.277, P=0.833). Conclusions: The Demodex infestation has some effects on the pathogenesis of MGD. The treatment of MGD may help to decrease the number of Demodex and thus relieve the ocular discomfort.(Chin J Ophthalmol, 2017, 53:193-197).