Demodex folliculorum mite density is associated with reduced cornea subbasal nerve density in patients with Dry Eye Disease

Abstract

Purpose : Demodex folliculorum are intradermal ectoparasites that are associated with dry eye disease (DED) and Blepharitis. In Vivo Confocal Microscopy (IVCM) been used clinically to evaluate anterior segment health, visualize abnormalities in corneal nerves, and identify the presence and extent of D. folliculorum infestation. This study sought to assess corneal nerve alterations in patients with D. folliculorum.

Methods : This retrospective study included 57 patients in three groups: Both DED and D. folliculorum blepharitis (n=12; 6M:6F; mean 52.085.34 years), DED alone (n=19; 7M:12F; mean 44.322.48 years), and normal controls (n=26; 10M:16F; mean 48.81 years).Patients received laser IVCM (Heidelberg Retinal Tomograph 3/Rostock Cornea Module) of the central corneal subbasal nerve plexus, as well as a D. folliculorum examination of the eyelid margin at the lash follicles. Subbasal nerve density was compared among the groups using ANOVA post hoc LSD. Association between density of mites and nerves was analyzed using Pearson’s correlation coefficient. Data reported as meanSEM in mm/mm².

Results : No significant differences were observed in gender (p=0.741) and age (p=0.248) of the participants among the groups. Patients with both DED and D. folliculorum blepharitis had a reduced total central corneal nerve density (15.69±1.49) compared to both DED alone (19.63±1.25; p=0.0001) and normal controls (22.60±0.77; p=0.042). Additionally, there was a negative correlation between mite density and subbasal nerve density, with a higher density of mite per lash follicle correlating to a reduced subbasal nerve density (R=-4.86; p<0.0001). A similar relationship was found in subbasal nerve branch density, with a decreased density in patients with DED and D. folliculorum (7.07±1.01) compared to DED alone (11.15±1.08; p=0.006), and normal controls (12.62±0.65; p=0.0001) and an inverse relationship between mites and branch density (R=-0.493; p<0.0001).

Conclusions : Patients experiencing both DED and D. folliculorum have decreased subbasal nerve density compared to healthy patients, and DED alone. IVCM analysis reveals that D. folliculorum may play a larger role in ocular surface damage and DED than previously estimated.

This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.