Functional and structural evaluation of the meibomian gland using a LipiView interferometer in thyroid eye disease

Objective: The purpose of this study was to evaluate the structure and function of the meibomian gland and the incomplete blinking rate to understand the pathophysiology of dry eye in thyroid eye disease (TED) patients. Methods: Patients who were diagnosed with TED were enrolled between October 2015 and February 2016. Clinical measurements were performed in the following order: (i) external examination (Hertel exophthalmometer and palpebral fissure height), (ii) LipiView interferometer (lipid layer thickness [LLT], incomplete blinking rate, and meibography), (iii) slit-lamp biomicroscopy (corneal surface staining, tear breakup time, meibum expression, Marx line). Results: Thirty eyes of 30 TED patients (male = 8; female = 22) were included in this study. The TED patient population had a mean age of 42.9 ± 11.8 years and a mean clinical activity score (CAS) of 2.33 ± 1.60. The meiboscore was 1.17 ± 0.90 in the upper eyelid and 0.70 ± 0.65 in the lower eyelid; scores were significantly higher in the upper eyelid (p < 0.001). The mean LLT was 82.43 ± 24.52 nm, and the mean incomplete blinking rate was 51.04 ± 33.62% (0-100%). CAS was the only variable that correlated with the meiboscore. There was no significant correlation between incomplete blinking and a degree of palpebral fissure height or proptosis. Conclusions: Tear film instability due to increased incomplete blinking can cause dry eye in TED. In addition to the increase in CAS, meibomian gland dysfunction may also be a cause of dry eye in TED. However, further comparative studies are needed to confirm these results.