Background: To evaluate exophthalmos by Hertel exophthalmometer (HE) compared to computed tomography (CT), and extraocular muscle width on CT and its relation with the clinical course in patients with thyroidal ophthalmopathy.
Methods: On reviewed 118 orbits from 59 patients (50 women, mean age 40.6 y., range 12-84) who suffered a thyroidal ophthalmopathy (Graves' disease, n = 57; Hashimoto's thyroiditis, n = 2). Muscle width was evaluated using coronal and mid-axial scans in all cases. Medial rectus (MR) width was analysed by Hallin and Feldon technique.
Results: Exophthalmos by HE was 22.5 +/- 2.5 and 23.2 +/- 3.2 mm (right-RE/left eye-LE), and CT 20.8 +/- 3.2 and 20.9 +/- 2.9 mm (p < 0.00001, r = 0.72 and 0.65, respectively). MR width on mid-axial scan was 4.1 +/- 1.6 and 4.2 +/- 1.5 mm (RE/LE). On coronal scans, MR was the muscle more often enlarged followed by superior, inferior and lateral rectus.
Conclusions: Exophthalmos measured by HE was greater than by CT-measured one, but with a good correlation. Muscle were not equally affected, being MR the most frequently enlarged. MR-width was not related to duration and severity of disease.