Investigation of Conjunctival Goblet Cell and Tear MUC5AC Protein in Patients With Graves' Ophthalmopathy

Purpose: The aim of this study was to investigate conjunctival goblet cell density (GCD) and tear mucin-5AC (MUC5AC) protein levels in patients with Graves' ophthalmopathy (GO) and their association with dry eye indicators. Methods: A total of 99 patients with GO (54 active, 45 inactive) and 40 healthy controls were recruited. Comprehensive ophthalmic examinations, including the external eye, ocular surface, GCD, and tear MUC5AC ELISA, were performed. The GCD examination was performed in temporal bulbar conjunctiva, including IVCM GCD by in vivo confocal microscopy (IVCM) and filled GCD of cytokeratin-7 and MUC5AC-positive coimmunomarkers by impression cytology. Tear MUC5AC protein was detected using samples extracted from Schirmer strips. Results: The GO group showed a significant decrease in IVCM GCD, filled GCD, and normalized tear MUC5AC protein compared to controls, with the active GO group showing the greatest decrease (all P < 0.05). Tear MUC5AC protein levels in GO correlated with those of IVCM GCD (r = 0.40, P < 0.001) and filled GCD (r = 0.54, P < 0.001, respectively). Higher ocular surface disease index (r = -0.22, P < 0.05; r = -0.20, P < 0.05; r = -0.21, P < 0.05) and lisamine green staining (r = -0.23, P < 0.05; r = -0.38, P < 0.001; r = -0.42, P < 0.001) were associated with lower tear MUC5AC protein levels, IVCM GCD, and filled GCD, respectively, which decreased with increasing clinical activity score (r = -0.24, P < 0.05; r = -0.28, P < 0.01; r = -0.27, P < 0.01) and conjunctival congestion score (r = -0.27, P < 0.01; r = -0.33, P < 0.001; r = -0.42, P < 0.001). Conclusions: The goblet cell count and tear MUC5AC protein in GO eyes were decreased, possibly due to ocular surface inflammation. Translational Relevance: This study observed the change of tear film mucin in GO patients.