The eye socket is a bony cup that surrounds and protects the eye. The rim of the socket is made of fairly thick bones, while the floor and nasal side of the socket is paper thin in many places. A fracture is a broken bone in the eye socket involving the rim, the floor or both.
Orbital rim fracture — These are caused by a direct impact to the face, most commonly by an automobile dashboard or steering wheel during a car crash. Because a great deal of force is required to cause these fractures, they often occur with extensive injuries to other facial bones, and sometimes injuries to the brain. Even if the damage is limited to the eye area, there may be additional injuries to the eye itself, such as the optic nerve (responsible for vision), the eye muscles, the nerves that provide sensation in the forehead and cheek, the sinuses around the eye and the tear duct. There are two types of orbital rim fractures. A zygomatic fracture involves the lower edge of the eye rim, which is part of the cheekbone. A frontal bone fracture or frontal sinus fracture involves the upper edge of the eye rim, which is part of the forehead's frontal bone.
Indirect orbital floor fracture ("blowout fracture") — This occurs when the bony rim of the eye remains intact, but the paper thin floor of the eye socket cracks or ruptures. This can cause a small hole in the floor of the eye socket that can trap parts of the eye muscles and surrounding structures. The injured eye may not move normally in its socket, which can cause double vision. Most blowout fractures are caused by an impact to the front of the eye from something bigger than the eye opening, such as a baseball, a fist or an automobile dashboard.
Direct orbital floor fracture — If an orbital rim fracture extends into nearby parts of the eye socket floor, both the rim and the socket floor are fractured.Approximately 2.5 million traumatic eye injuries, including eye socket fractures, occur each year in the United States. About 85% of these injuries happen by accident, during contact sports, at work, in car crashes or while doing home repair projects. About 15% are caused by violent assaults. Men suffer from traumatic eye injuries about four times more often than women do. The average age of the injured person is about 30. The source of the injury is usually a blunt object — baseball, hammer, rock, piece of lumber — and the most frequent place of injury is the home. At one time, eye injuries were common in motor vehicle accidents, usually when a victim's face struck the dashboard. Such eye injuries have decreased dramatically because more cars have airbags, and most states have laws mandating the use of seat belts.