Purpose: To compare the clinical findings, tear film function and impression cytology between patients with active and inactive Thyroid Eye Disease (TED).
Methods: A total of 56 patients with TED and 30 controls were recruited in this prospective observational cohort study. TED patients were divided into active TED and inactive TED types according to a seven-point modified formulation of the Clinical Activity Score (CAS). All participants underwent full eye examinations including Ocular Surface Disease Index (OSDI) score, tear film break-up time (TBUT), fluorescein staining and Schirmer I test. Thirty nine patients with thyroid-associated orbitopathy (TAO) received Nelson's grade with conjunctival impression cytology. Proptosis, palpebral fissure width and lagophthalmos were assessed.
Results: Ocular surface parameters including proptosis, palpebral fissure width and lagophthalmos did not differ between active and inactive TED patients (P>0.05). Both active and inactive TED patients obtained higher fluorescein staining scores, lower TBUT scores and significantly lower Schirmer test scores than those of controls (P<0.001 for all). Additionally, the TBUT score was significantly lower and the OSDI score significantly higher in the active TED group compared with those in the inactive TED group (P<0.001 for both). Impression cytology revealed a higher proportion of grade 2-3 changes in the active TED group compared with the inactive TED group (P<0.001).
Conclusion: Orbital inflammation in TED patients may lead to decreased tear film stability and ocular surface squamous metaplasia.