Correlation between Corneal In Vivo Confocal Microscopy and Clinical Findings in Dry Eye Disease

Abstract

Purpose : There is discrepancy in reported studies on correlations between in vivo confocal microscopy (IVCM) findings in the cornea and clinical parameters of dry eye disease (DED). The purpose of our study is to evaluate this correlation in our patients.

Methods : This cross-sectional study included 80 eyes of 40 patients with DED which was defined as symptoms of DED plus abnormal tear breakup time (TBUT) or Schirmer test. Patients with previous ocular surgery or contact lens use were excluded. All patients underwent a comprehensive ocular surface evaluation which included Ocular Surface Disease Index (OSDI) questionnaire, corneal fluorescein staining (CFS, NEI grading, 0-15), conjunctival lissamine green staining (LGS, NEI grading, 0-18), TBUT, Schirmer test with anesthesia, and tear osmolarity. In addition, IVCM was performed in the central cornea of both eyes. Three IVCM images of subbasal area were used to measure subbasal nerve fiber length (SNFL) and dendritic cell (DC) density by two independent masked observers. The average values of both observers were used for analysis. Correlations between IVCM parameters and clinical parameters were then investigated.

Results : There were 35 women and 5 men, with a mean age of 61.4±15.1 years (range, 26-86 years). The average values were 53.15 ± 25.4 for OSDI, 6.1 ± 4.3 for CFS, 3.5 ± 3.9 for LGS, 4.9 ± 2.5 seconds for TBUT, 10.6 ± 6.5 mm for Schirmer, and 300.6 ± 27.7 for tear osmolarity. The mean SNFL was 14.69 ± 6.15 mm/mm² and mean subbasal DC density was 114.4 ± 64.3 cells/mm². Correlation analysis showed that OSDI had significant correlation with CFS (P=0.001, r= 0.60) and Schirmer (P=0.017, r= -0.46). CFS also had significant correlations with LGS (P=0.001, r=0.58), TBUT (P=0.002, r= -0.57), and Schirmer ((P=0.003, r= -0.55). There was also a significant negative correlation between SNFL and age (P=0.028, r= -0.42). However, there were no statistically significant correlations between SNFL or DC density and other clinical parameters. Osmolarity also showed no correlations with any IVCM or clinical parameters.

Conclusions : There are no significant correlations between IVCM parameters and clinical signs or symptoms of DED. Caution should be exercised in clinical use of IVCM for DED evaluation.

This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.