Evolution of asymmetric proptosis during the active phase of thyroid eye disease.

To assess the evolution of proptosis asymmetry during the active phase of bilateral thyroid eye disease (TED). A retrospective study was conducted on patients with bilateral, active TED. Patients were measured by a single observer, using Hertel exophthalmometry from the time of initial presentation, during the active phase of TED, to the stable phase, 24-months later. Asymmetric proptosis was defined as a >2 mm intra-orbital difference in Hertel measurements. Fifty-one patients were enrolled. Patients presented at a mean time of 1.1 ± 2.9 months following the onset of TED symptoms. Stability of TED was established at 15.7 ± 12.3 months. At initial presentation, 41% of patients demonstrated asymmetric proptosis. Upon reaching the stable phase, asymmetric proptosis persisted in only 22% of patients. A decline in the rate asymmetric proptosis was greatest within the first 3 months of the active phase. Asymmetric proptosis is common in the setting of early active TED and decreases by 50% when the stable phase is reached. Therefore, diagnostic imaging is not routinely required to exclude alternative pathology in the cases of asymmetric TED. Perhaps more importantly, this finding supports the surgical paradigm of stable phase, graded orbital decompression, performed when the ultimate globe positions are achieved to avoid late postoperative asymmetry, resulting from the unanticipated evolution of proptosis when surgery is performed during the active phase of TED.