The Size of Extraocular Muscles Estimated by Computed Tomography in Patients Undergoing Orbital Wall Fracture Repair

ABSTRACT

PURPOSE: To determine the cross sections of extraocular muscles in patients with orbital fracture and to demonstrate a relationship among the cross sections, the size of orbital fracture, the soft tissue, and fat herniation and limitation of ocular movement. METHODS: The study included 87 patients (87 eyes) with orbital fracture. The cross section was defined as multiplication of the long axis and short axis. The ratio of the cross section in normal and injured eyes was calculated at preoperative and postoperative periods. RESULTS: The cross sections of all rectus muscles, except for the superior, increased in injured eyes and subsequently decreased postoperatively. After surgery, the cross sections of lateral and medial rectus muscles recovered to near normal but the inferior remained enlarged. The increased ratio of the short and long axis was significant but not the difference of the cross sections related to the short and long axis ratio. There was a preoperative difference between injured/normal cross section ratio in relation to the size of inferior fracture. There was postoperative normalization for the cross sections of inferior rectus muscles with the restrictive limitation due to inferior fracture. CONCLUSIONS: The cross sections increased mostly after orbital fracture and subsequently decreased postoperatively. There was a change in the cross section ratio with the size of inferior fracture at preoperative period but there was no change in the cross sections related to the restrictive or paralytic limitation, except for eyes with the restriction secondary to inferior fracture. These were significantly normalized postoperatively in cross section.