Dry eye syndrome in thyroid eye disease patients: The role of increased incomplete blinking and Meibomian gland loss

To compare the structure and function of the Meibomian gland and eyelid blinking patterns between thyroid eye disease (TED) patients with dry eye and nonthyroidal dry eye (DE) patients.This was a prospective, cross-sectional and observational study. Clinical measurements were performed as follows: (1) external examination, (2) Lipiview® Interferometer (lipid layer thickness, incomplete blinking rate and meibography) and (3) slit-lamp biomicroscopy (corneal staining, tear break-up time (TBUT), meibum expression).The TED and DE groups included 98 and 62 patients, respectively. The meiboscores of the upper eyelid in TED and DE groups were significantly different (1.21 ± 0.76 and 0.94 ± 0.71, respectively, p = 0.046). The rate of incomplete blinking was 53.3 ± 34.5 and 34.6 ± 36.3%, respectively, and was significantly higher in the TED group (p = 0.006). In the TED group, CAS was the only variable affecting the meiboscore of the upper and lower eyelids (p = 0.031, 0.039, respectively). Significantly, active TED patients had more decreased basal tear secretion than inactive TED patients (7.4 ± 2.1 mm versus 8.5 ± 1.5 mm, p = 0.024). Moreover, active TED patients had decreased meibum expression in both upper and lower eyelids compared with inactive TED patients (2.20 ± 0.88 versus 1.08 ± 0.84, p = 0.002 in upper eyelid, 2.10 ± 0.88 versus 1.18 ± 0.88, p = 0.007 in lower eyelid, respectively).In TED patients, incomplete blinking and loss of Meibomian gland structure in the upper eyelid were more prominent than in DE patients. CAS was a factor affecting the structural loss of Meibomian glands in TED individuals.