In Vivo Confocal Microscopy Demonstrates Increased Density of Immune Dendritiform Cells in the Peripheral Cornea of Patients with Dry Eye Disease Compared to Normal Controls

Abstract

Purpose : In vivo confocal microscopy (IVCM) is a non-invasive instrument for detecting dry eye-associated subclinical inflammation. The purpose of this study was to assess inflammatory changes in the peripheral cornea by analyzing epithelial immune dendritiform cell (DC) density and morphology in DED as compared to normal controls.

Methods : This is a prospective, cross-sectional, case-control study evaluating 46 patients with DED and 20 age and sex-matched controls (p>0.05). All 4 peripheral corneal quadrants (superior, inferior, temporal and nasal) were imaged by laser IVCM. Three representative images were analyzed for DC density and morphology (DC area and DC field) by two observers in a masked fashion. A p-value <0.05 was considered statistically significant.

Results : The mean age of DED group was 54.30±11 and that of normal controls was 49.05±9.7 years, respectively (p>0.05). DC density, DC area and DC field in the peripheral corneal quadrants ranged from 49.23±49.12 to 84.73±77.78 cells/mm², 145.89±52.17 to 150.91±62.72m², and 208.53±115.31 to 351.97±286.51m². There was a significant difference in DC density between DED and controls groups for all quadrants (p<0.05). In contrast, the morphological parameters did not show statistically significant changes between the quadrants (p>0.05). DC parameters did not show statistically significant differences between evaporative and mixed subtypes of DED for any peripheral quadrant. Although mean DC density was higher in DED than in controls for all quadrants, the inferior quadrant showed increased DC density in 68% (1 SD above normal) and 48% (2 SD above normal) of patients. The nasal, temporal and superior quadrants demonstrated increased DC density between 37% and 43% (1 SD above normal), and between 14.8% and 27% (2 SD above normal) in DED.

Conclusions : The peripheral cornea demonstrates increased level of immune cell alterations in DED compared to controls, with the inferior cornea showing the highest level of subclinical inflammation. While inflammation cannot be detected by clinical examination, IVCM may be used to stratify DED patients with immune cell alterations for clinical trials or anti-inflammatory therapy.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.