Real-time ultrasound elastographic evaluation of extraocular muscle involvement in Graves' ophthalmopathy.

: To evaluate the affected extraocular muscles (EOMs) of patients with Graves' ophthalmopathy (GO) using real-time ultrasound elastography (UE) and to compare these results with those of healthy subjects.: This prospective, comparative case series included 70 eyes of 35 patients with moderate-to-severe GO with type 2 orbitopathy (myogenic variant) according to their computed tomography (CT) scans. Forty-six eyes of 23 healthy subjects were evaluated as the control group. The strain ratio of orbital fat to medial rectus was calculated as the ratio of the medial rectus to orbital fat tissue, and the strain ratio of orbital fat to lateral rectus was calculated as the ratio of lateral rectus to orbital fat tissue.: The strain ratio of orbital fat to medial rectus was 3.03 ± 1.25 (range: 1.05-5.07) in the GO group, and 0.54 ± 0.20 (range: 0.14-1.08) in the control group ( = .0001). The strain ratio of orbital fat to lateral rectus was 0.97 ± 0.29 (range: 0.56-1.55) in the GO group, and 0.63 ± 0.23 (range: 0.18-1.09) in the control group ( = .0001).: By using real-time UE, we found the medial and the lateral recti of GO patients to be stiffer compared to those of healthy subjects.