Corneal Epithelial Immune Dendritic Cell Alterations in Subtypes of Dry Eye Disease: A Pilot In Vivo Confocal Microscopic Study

Abstract

Purpose: To evaluate density and morphology of corneal epithelial immune dendritic cells (DCs) in different subtypes of dry eye disease (DED) using in vivo confocal microscopy (IVCM).

Methods: This retrospective study included 59 eyes of 37 patients with DED and 40 eyes of 20 age-matched healthy controls. Based on clinical tests, eyes with DED were categorized into two subtypes: aqueous-deficient (n = 35) and evaporative (n = 24). For all subjects, images of laser scanning in vivo confocal microscopy (IVCM) of the central cornea were analyzed for DC density and DC morphology (DC size, number of dendrites, and DC field). These DC parameters were compared among all dry eye and control groups.

Results: Compared with the controls, patients with DED had significantly higher DC density, larger DC size, higher number of dendrites, and larger DC field (all P < 0.001). Comparison between aqueous-deficient and evaporative subtypes demonstrated that DC density was significantly higher in aqueous-deficient subtype (189.8 ± 36.9 vs. 58.9 ± 9.4 cells/mm2, P = 0.001). However, there were no significant differences in morphologic parameters between DED subtypes. When aqueous-deficient DED with underlying systemic immune disease (Sjögren's syndrome and graft versus host disease) were compared with nonimmune conditions, the immunologic subgroup showed significantly higher DC density, DC size, and number of dendrites (all P < 0.05).

Conclusions: Corneal IVCM demonstrated differential changes in DC density and morphologic DC parameters between subtypes of DED. These changes, which reflect the degree of immune activation and inflammation in DED, can be used for clinical practice and endpoints in clinical trials.

Figure 1

Measurement of morphologic parameters of DCs using ImageJ software. The size of DC was measured using the Threshold Function (A). The number of dendrites per cell was calculated manually. The DC field was calculated by measuring the area covered by a polygon joining the dendrite tips around each cell (B).

Figure 2

Corneal in vivo confocal microscopy images in normal controls (A), evaporative DED (B), as well as nonimmunologic (C) and immunologic (D) subgroups of aqueous-deficient DED demonstrate differential alterations in DC density and morphologic parameters in different subtypes of DED compared with controls.

Figure 3

Dendritic cell density and morphologic parameters in evaporative and aqueous-deficient subtypes of DED as well as the healthy controls. For both the aqueous-deficient and evaporative subtypes, DC density and all morphologic parameters were significantly higher than the control group, except for DC field in the evaporative subtype. Dendritic cell density, but not morphologic parameters, was significantly higher in the aqueous-deficient subtype as compared with the evaporative subtype.

Figure 4

Dendritic cell density and morphologic parameters in immunologic and nonimmunologic subgroups of the aqueous-deficient subtype of DED as compared with the evaporative subtype. The DC density, DC size, and number of dendrites, but not DC field, were significantly higher in the immunologic subgroup as compared with the nonimmunologic subgroup. In addition, although there were no significant differences in any IVCM parameters between the nonimmunologic subgroup and the evaporative subtype, the immunologic subgroup had significantly higher DC density and number of dendrites than the evaporative subtype.