An orbital fracture is a break in one or more of the bones that form the eye socket, a cone-shaped bony structure known as the orbit. The orbit serves as a protective enclosure for the eyeball, along with the muscles, nerves, and fat that surround it. These fractures commonly result from blunt force trauma to the face, such as impacts sustained during sports injuries, assaults, or motor vehicle accidents. The resulting damage can range from minor cracks to severe structural collapse, sometimes affecting the function of the eye itself.
Understanding the Anatomy and Fracture Types
The orbit is a complex structure formed by seven different bones that create the protective socket. The walls of this bony cavity vary significantly in thickness. The outer side, or lateral wall, is the most robust. Conversely, the floor and the inner side, or medial wall, are notably thinner, which makes them more vulnerable to injury.
The seven bones are:
- Frontal bone
- Zygomatic bone
- Maxilla bone
- Lacrimal bone
- Ethmoid bone
- Palatine bone
- Sphenoid bone
Orbital fractures are broadly categorized based on location and mechanism. The first type is the orbital rim fracture, which involves the thick, outer edge of the socket. This injury requires a high-impact force and is often associated with other complex facial fractures.
The second, more common category is the blowout fracture, which involves the thin walls of the orbit while the sturdy outer rim remains intact. Blowout fractures most frequently affect the orbital floor or the medial wall. This injury often occurs when a blunt object strikes the eye and pushes it backward. The resultant increase in internal pressure (hydraulic theory) causes the weakest wall to give way. An alternative explanation, the buckling theory, suggests the force of the impact on the rim is transmitted through the bone, causing the thinner walls to fracture.
Identifying Signs and Symptoms
Immediately following the injury, significant periorbital swelling and bruising, often referred to as a black eye, are nearly universal occurrences. This swelling can sometimes be so pronounced that it temporarily makes a comprehensive eye examination difficult. Pain is also a consistent symptom, and it often worsens noticeably when the injured person attempts to move the affected eye.
One concerning symptom is diplopia, or double vision, which is a major indication of a more severe injury. This double vision frequently occurs because the trauma has caused a piece of the thin orbital wall to break off and trap one of the extraocular muscles. When the muscle responsible for moving the eye is caught in the fracture site, it is unable to function properly, leading to misalignment of the eyes and the resulting perception of two images. If the fracture is large, the eyeball may also appear sunken into the socket, a condition called enophthalmos.
Damage to the infraorbital nerve, which runs along the orbital floor, can cause numbness or a tingling sensation. This altered sensation is felt in the cheek, the upper lip, and sometimes the upper teeth on the side of the fracture. A final, less common sign is orbital emphysema, which occurs when air from an adjacent sinus is forced into the soft tissues around the eye.
Diagnostic Procedures and Initial Care
The medical assessment for a suspected orbital fracture begins with a thorough physical examination focused on the eye and its function. Medical professionals will test visual sharpness, check the extent of the eye’s movement in all directions, and carefully measure the eye’s position within the socket. Initial imaging is necessary to confirm the diagnosis and determine the precise extent of the bone damage.
A Computed Tomography (CT) scan is the established standard for diagnosing orbital fractures, providing rapid and detailed cross-sectional images of the bony structures. The CT scan is far superior to conventional X-rays, as it clearly shows the size and location of the fracture, the degree of bone displacement, and whether any soft tissue or muscle has become entrapped. Thin-cut CT images allow surgeons to accurately measure the defect and plan reconstruction.
Initial care protocols focus on stabilizing the patient and mitigating complications while swelling subsides. Patients are typically given pain medication and instructed to use ice packs. Prophylactic antibiotics may be prescribed because the fracture often breaks the barrier between the orbit and the adjacent sinuses, introducing a risk of infection. Patients are strongly advised to avoid blowing their nose for several weeks, as this action can force air into the orbit and potentially cause further swelling or visual problems.
Surgical and Non-Surgical Treatment Options
The treatment approach for an orbital fracture depends on the size of the break and the severity of the symptoms. Small, uncomplicated fractures that do not involve muscle entrapment or significant displacement can be managed non-surgically with observation. This conservative approach includes monitoring the patient closely to ensure symptoms like double vision resolve as the initial swelling recedes. Non-surgical management is appropriate when the fracture is small, typically involving less than 50% of the orbital floor, and there is no limitation of eye movement.
Surgical repair becomes necessary when the fracture threatens long-term function or appearance. Indications for an operation include persistent double vision in the central field of gaze, evidence of muscle or soft tissue entrapment, or enophthalmos of greater than two millimeters. Surgery is also indicated for large fractures involving more than half of the orbital floor, as these defects are likely to result in the eye sinking back into the socket.
The timing of the operation is often delayed for seven to fourteen days after the injury to allow facial swelling to decrease, which provides the surgeon with a clearer field of view. During the procedure, the trapped muscle or tissue is freed, and the bony defect is bridged to restore the original shape of the orbit. Surgeons utilize various materials for this reconstruction:
- Titanium mesh
- Porous polyethylene
- Resorbable sheeting made of polymers like polylactic acid
- Resorbable sheeting made of polymers like polyglycolic acid
The goal of the surgery is to restore the normal volume of the orbital cavity, preventing long-term visual issues and cosmetic deformity.