The evaluation of retrobulbar fat tissue in Graves' orbitopathy with shear-wave ultrasound elastography

To evaluate retrobulbar adipose tissue of patients with active and inactive Graves' orbitopathy (GO) by shear-wave ultrasound elastography (SWE).

Followed-up in our ophthalmology clinic due to GO, 72 eyes of 36 patients and 38 eyes of 19 healthy controls were included in this cross-sectional case-control study. Graves' patients were divided into two subgroups under clinical activity score (CAS): active Graves' orbitopathy (AGO) (CAS ≥ 3) and inactive Graves' orbitopathy (IGO) (CAS < 3). SWE measurement values of retrobulbar adipose tissue of all participants were recorded in meters/second, and the intergroup comparisons were performed.

Thirty-four eyes of 17 patients in AGO, 38 eyes of 19 patients in IGO, and 38 eyes of 19 participants in the control group were included in the study. Mean values measured from retrobulbar adipose tissue through SWE were 1.00 ± 0.01 m/sec in AGO, 1.16 ± 0.01 m/sec in IGO, and 0.94 ± 0.01 m/sec in the control groups. Even so, the mean SWE value was significantly higher in the IGO group than in the other groups (p < 0.001). Mean SWE values were significantly higher in the AGO group than in the controls (p = 0.008). In the correlation analysis performed, a significant positive correlation was found between SWE and Hertel exophthalmometer measurement values (p = 0.026, r = 0.212), and thyroid-stimulating hormone receptor antibody (TSHR-Ab) levels (p = 0.018, r = 0.224).

We detected SWE values of retrobulbar adipose tissue high in GO, especially in the IGO group. Such a situation, which we associated with the development of fibrosis, may be an indicator of unresponsiveness to immunomodulatory treatments.