Morphological alterations of corneal basal nerves in adult patients with mild to moderate dry eye by in vivo confocal microscopy

Background: /Objectives: In previous studies, the morphological differences of corneal basal nerves in dry eye patients may be related to severity and aging.The aim of the study was to evaluate the morphological alterations of corneal basal nerves in adult patients with mild to moderate dry eye disease (DED) by in vivo confocal microscopy (IVCM). Subjects/Methods: Prospective, cross-sectional study.Forty-two adult patients (19-44 years) with mild to moderate DED and 16 sex- and age-matched healthy controls were included in this study. All patients had a history of dry eye lasting less than 12 months.The Ocular Surface Disease Index (OSDI), tear film break-up time (TBUT), sodium fluorescein staining andSchirmer’s test, and IVCM were used to observe central corneal basal nerve parameters, including nerve density, main number, branch number, width, reflectivity, tortuosity and beading number. Results: : Compared with the 16 healthy subjects (16 eyes), the 42 patients (42 eyes) with DED showed higher nerve density (21.889±3.459 vs. 16.653±1.793, P<0.001) and branch numbers (9.694±2.817 vs. 4.403±1.539, P<0.001). The main nerve numbers (6.720±1.027 vs. 6.328±0.521, P=0.199) were not significantly increased. Moreover, greater nerve width, reflectivity, tortuosity and beading numbers were observed in the DED patients (P <0.001). In the DED group, nerve density was positively correlated with main numbers, branch numbers, width and reflectivity (r=0.513, P<0.000, r=0.790, P<0.000, r=0.420, P=0.006 and r=0.526, P<0.000, respectively) and negatively correlated with tortuosity (r=-0.473, P=0.02). Conclusions: : Adult patients with mild to moderate DED demonstrated higher nerve density, branch numbers, width, tortuosity, reflectivity and beading numbers than normal subjects. IVCM may be a sensitive indicator for assessing mild to moderate DED in the early stage.