Hertel Exophthalmometry and Computed Tomography for the Evaluation of Exophthalmos in Patients with Thyroid-Associated Ophthalmopathy

Abstract

Objective: To compare the values of exophthalmos measured by computed tomography (CT) and Hertel exophthalmometry (HE) in patients with thyroid-associated ophthalmopathy (TAO). Material and Methods: One hundred and seventy eyes were examined in 85 patients with TAO. Each patient underwent a complete ophthalmic examination, Hertel exophthalmometry, and CT of the orbits through a 16-slice CT scanner (Bright Speed, General Electric), measuring the extraocular muscles, the total muscle thickness sum (MTS), and proptosis. The patients were divided into two groups-with activity and without TAO activity, the activity being assessed by means of the Clinical Activity Score (CAS) and the severity-according to the EUGOGO classification. Results: TAO activity was detected in 45 patients (90 eyes, 53%) with MTS of 23.54 ± 5.73 mm, IOP of 19.78 ± 4.49 mm Hg, Hertel exophthalmos of 23.08 ± 4.19 mm and measured by CT-23.32 ± 4.33 mm. Forty patients (80 eyes, 47%) were without TAO activity, with MTS of 19.28 ± 4.03, IOP of 16.6 ± 4.51 mm Hg, Hertel exophthalmos of 20.03 ± 3.84 mm and measured by CT-19.84 ± 4.47 mm. A correlation was detected between exophthalmos and: MTS, IOP, the activity and severity of TАО. High congruence was established between the two methods of measuring exophthalmos-CT and HE (Pearson correlation, r = 0.690, p = 0.000). Conclusion: Our results showed a high degree of consistency between Hertel exophthalmometry and multidetector CT for the evaluation of exophthalmos in patients with TAO. Exophthalmos is an important clinical feature and its measurement and monitoring over time assess the clinical course and outcome of treatment.