[Evaluation of ocular surface status and function in primary Sjögren's syndrome with hypothyroidism].

OBJECTIVE

To explore the effect of hypothyroidism (HT) on the ocular surface status of patients with primary Sjögren's syndrome-related dry eye (pSS-DED).

METHODS

The cross-sectional study included 36 patients with pSS-DED who were treated at the dry eye clinic of Peking University Third Hospital from December 2020 to June 2021, of whom 12 were pSS-DED patients combined with HT. In the same period, 24 patients with simple dry eye disease (DED) were served as a control group. All the patients filled out the Ocular Surface Disease Index (OSDI) questionnaire, and performed tear film break-up time (BUT), Schirmer test, tear meniscus height, corneal/conjunctival fluorescein staining, meibomian gland secretion capacity, meibum evaluation and confocal microscope examination.

RESULTS

(1) Compared with pSS-DED and simple DED patients, pSS-DED +HT patients had lower average BUT [(2.7±0.8) s], Schirmer test [(4.9±4.8) mm] and tear meniscus height [(0.13±0.03) mm], and the difference was statistically significant (=12.43, < 0.01; =6.96, < 0.01; =3.31, < 0.05). (2) Compared with DED and pSS-DED patients, the meibomian gland secretion capacity and meibomian trait scores of pSS-DED+HT patients were mainly distributed in the high division. There were statistically significant differences in the distribution of secretion capacity of meibomian glands (=10.72, < 0.05) and meibomian trait assessment scores (=8.34, < 0.05) among the three groups. (3) Serum total thyroxine and serum free thyroxine levels in the pSS-DED+HT patients showed positive correlation ( < 0.05, < 0.05) with their BUT (=0.60, 0.60), Schirmer's test (=0.64, 0.66) and tear river height (=0.61, 0.62), independent of lid gland secretory capacity; no significant correlation was found between thyroid-stimulating hormone, anti-thyroglobulin antibody and lid gland secretory capacity. Thyroid hormone, anti-thyroglobulin antibody, and thyroid peroxidase antibody were not found to be significantly correlated with ocular surface status. (4) Compared with pSS-DED, the fiber density of the subbasal nerve plexus in pSS-DED+HT group decreased (=2.06, < 0.05), and the curvature score increased (=2.13, < 0.05).

CONCLUSION

The ocular surface condition of pSS-DED patients with HT is worse than that of pSS-DED and DED patients. The main manifestations are that tear secretion, tear film stability, secretory function of the meibomian glands, meibum trait and fiber density of the subbasal nerve plexus decrease while the curvature increases. The mechanism might be related to the decrease in thyroid hormone production.