Thyroid Eye Disease Asymmetric Proptosis Reduces Upon Reaching Stability Phase

Asymmetric proptosis is common in early active thyroid eye disease (TED) but decreases by 50% when the stability phase is reached, according to a study published in Orbit. This finding supports a reduced need for routine diagnostic imaging and highlights the usefulness of stable phase, graded orbital decompression surgery in patients with TED.

Researchers enrolled 51 patients (72% women; mean age, 58.4±17.1 years) who presented for treatment at a mean 1.1±2.9 months following TED symptoms in the retrospective analysis. Patients underwent exophthalmometry measurements at baseline and at a 24 month follow-up visit. Asymmetric proptosis was defined as an intra-orbital difference in exophthalmometry measurements greater than 2 millimeters (mm). Thyroid treatments included antithyroid medication (53%), radioactive iodine ablation (41%) and thyroidectomy (8%). Patients who were treated with immunosuppressive therapy received a combination of orbital radiotherapy and oral prednisone (75%) or oral prednisone alone (6%). 

Among the cohort, 41% of patients presented with asymmetric proptosis, which persisted in 22% of these patients upon reaching the stable phase. Asymmetric proptosis declined the most within the first 2 months of the active phase and TED stability was established at 15.7±12.3 months. Investigators note that asymmetric proptosis rates changed throughout the active phase and 69% of patients exhibited it at some point in the study.

Older age was also associated with higher asymmetric proptosis rates at initial presentation, and individuals older than 60 years had a higher prevalence of the condition over the course of their disease (P =.017).  

“The clinical implications of this finding include a reduced concern for a sinister pathology responsible for proptosis asymmetry when seen early in the active phase of TED, reducing the need for routine diagnostic imaging in these cases,” according to the researchers. “More importantly, these findings support the surgical paradigm of stable phase graded orbital decompression performed when the ultimate globe positions have been achieved to avoid late post-operative asymmetry, resulting from the otherwise unanticipated natural evolution of proptosis when surgery is performed in the acute phase.”

Study limitations include a retrospective nature, small sample size, possible skewing of patient demographics due to referral patterns, and potential confounding due to radiotherapy and prednisone treatments.

Reference

Tran AQ, Zhou HW, Nanda T, et al. Evolution of asymmetric proptosis during the active phase of thyroid eye disease. Orbit. Published online July 8, 2022. doi:10.1080/01676830.2022.2088807