Purpose: To examine the density and morphology of Langerhans cells (LCs) in the cornea of patients with thyroid-associated ophthalmopathy (TAO).
Methods: Forty patients with TAO and 20 healthy volunteers were studied. All subjects underwent a thorough ophthalmic examination of both eyes. The ocular surface status was assessed by Ocular Surface Disease Index (OSDI) symptom questionnaires, tear break-up time (BUT), fluorescein staining and the Schirmer test. Laser scanning in vivo confocal microscopy was applied to evaluate the LC density and morphology in both central and peripheral cornea. The correlations between confocal microscopy data and clinical data were also analyzed.
Results: The OSDI and fluorescein staining values were significantly higher, while BUT and Schirmer test scores were lower in both active and inactive TAO patients compared to the controls. Central LC densities of patients with active TAO (76.38 ± 67.77 cell/mm(2)) and inactive TAO (47.49 ± 38.58 cell/mm(2)) were both significantly higher than those of the controls (21.46 ± 21.74 cell/mm(2)). The number of LCs in the peripheral cornea was also significantly increased in the active TAO group (131.53 ± 74.18 cell/mm(2)) compared to the control group (70.21 ± 37.76 cell/mm(2)). Central LC morphology (LCM) values were significantly higher in both active (1.77 ± 0.63) and inactive (1.51 ± 0.63) TAO groups compared to the control group (1.01 ± 0.80), whereas peripheral LCM scores of the two TAO groups were increased without statistical significance. There were significant correlations between both central LC density and central LCM scores and clinical data, including clinical activity score, OSDI and Schirmer test scores, and between peripheral LC density and OSDI and Schirmer test scores. No significant correlations were found between peripheral LCM scores and clinical data.
Conclusions: The increase of corneal LCs in density and maturation in patients with TAO reflects an activated state of the local immune system, which indicates an inflammatory process in the cornea of TAO.
Keywords: In vivo confocal microscopy; Langerhans cells; inflammation; ocular surface; thyroid-associated ophthalmopathy.