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

Purpose: 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. Methods: 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). Results: 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). Conclusion: 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.