Thyroid-associated periorbitopathy: eyebrow fat and soft tissue expansion in patients with thyroid-associated orbitopathy.

OBJECTIVE To compare soft tissue and fat volumes in the supraorbital area of healthy patients and patients with thyroid-associated orbitopathy (TAO) using 3-dimensional reconstruction software. METHODS The superiolateral orbital area was delineated on a bony framework. Three-dimensional reconstruction and volumetric calculation of the retro-orbicularis oculi fat (brow fat), galeal fat (including the retro-orbicularis oculi fat), and soft-tissue muscle were performed. RESULTS We analyzed 100 computed tomographic scans from 48 patients with TAO and 52 control subjects. All patients showed an age-related increase of fat volumes. The mean total eyebrow volume was greater in patients with TAO vs healthy control subjects (P < .001). Galeal fat (P = .02) and retro-orbicularis oculi fat (P = .01) volumes were significantly higher in patients with TAO vs control subjects. Soft-tissue muscle volume decreased with age in healthy females but remained constant in the aging female group with TAO. Both total volume and brow thickness did not appear to change with age in healthy patients but exhibited an increase in the female population with TAO. CONCLUSIONS This study brings into focus the clinicopathologic entity of thyroid-associated periorbitopathy. Three-dimensional evaluation of computed tomographic scans can provide information on volumetric changes in the eyebrow profile of patients with TAO. Further investigation of the biologic and morphologic changes of eyebrow fat and soft tissue in patients with TAO may help better characterize, classify, and guide their treatment.