A break in the floor of the bony socket (orbit) surrounding the eye. The usual cause is a hard blow from a nonpenetrating blunt object. The fracture may entrap some of the muscles that move the eye, causing double vision, especially when the person looks up. Other symptoms include bruising around the eye, protrusion of the eyeball, and numbness in the cheek or upper teeth. Tests, including CT (computed tomography) scanning, are performed to determine whether eye muscles are involved in the fracture. A blow-out fracture involving muscles requires surgical repair, which is usually performed within 14 days of the injury. If no muscles are involved, if there is no persistent diplopia (double vision), or if no serious cosmetic defect is present, the fracture is allowed to heal on its own.