Degeneration of Corneal Sensation and Innervation in Patients with Facial Paralysis: A Cross-Sectional Study Using in Vivo Confocal Microscopy

Purpose: Facial paralysis (FP) leads to diverse periocular complications which threats visual acuity and affects corneal nerve functionally and morphologically. This study aims to summarize the clinical ophthalmic outcomes, corneal sensation, and morphological alterations of subbasal nerve and dendritic cells (DCs) in patients with facial paralysis.Methods: We performed a cross-sectional study of 48 consecutive patients with facial paralysis at one tertiary hospital. Forty-eight healthy participants were enrolled as controls. The images of corneal nerves and epithelial DCs were detected by in vivo confocal microscopy (IVCM). Each patient received thorough ophthalmic examination, tear film function tests, corneal fluorescence staining and Cochet-Bonnet esthesiometry test. Clinical and morphologic data were compared with controls.Results: Forty patients (83.3%) showed corneal injuries from punctate epithelial defects to corneal ulcers and scars. Visual impairment and eyelid malposition were observed. Corneal sensitivity remarkably decreased (25.1 ± 23.8 mm) in the affected eyes and was correlated to diminished subbasal nerve density (P = .019, r = 0.387). Numbers of corneal main nerve trunks and branches were significantly reduced (P < .0001) while DCs were increased (P < .0001) in patients with FP when compared with controls. Nerve fiber density showed inverse association with DC density (P = .019, r = -0.389).Conclusions: Ocular complications including corneal erosions, loss of corneal sensation, visual impairment and eyelid malposition have largely affected patients with facial paralysis. Morphological changes of diminished corneal subbasal nerve and increased DCs were detected by IVCM. Corneal epithelial defect, corneal opacity, corneal sensation, dendritic cell density are factors associated with corneal subbasal nerve density. Patients with FP are suggested to have complete ophthalmic evaluation and early instruction on ocular prevention.