Anatomy of the Lacrimal Bone

The lacrimal bones are small, flat craniofacial bones located in the eye socket. These rectangular bones consist of two surfaces, one facing the nose, the other facing the eye.

Facial fractures can involve the lacrimal bone. Treatment for lacrimal fractures may simply involve rest, or reconstructive surgery may be needed, depending on the severity. 

Anatomy

The rectangular-shaped lacrimal bones are approximately the size of a small fingernail. Forming part of the eye socket, they have four borders and two surfaces, nasal and orbital. Viewed face on, the lacrimal bones would be hidden behind the nasal bones.

The pair of bones, one in each eye socket, sits at the front of the orbit, near the corner of the eye, closest to the nose. Supporting the eye, the lacrimal bones are the most fragile of the 14 facial bones.

The orbital surface of the lacrimal bone is divided by a ridge called the posterior lacrimal crest. A groove to the anterior of the crest is called the lacrimal groove. A long groove on the nasal surface portion of the nasal surface forms part of the middle nasal meatus. The nasolacrimal duct (tear duct) sits between the lacrimal and maxilla bones.

The lacrimal bone is the point of insertion of the orbicularis oculi muscle. It is a circular muscle that both closes the eyelids and helps with tear drainage.

Function

Lacrimal bones are a part of the lacrimal (tear production) system. The lacrimal system contains the lacrimal gland, which produces tears, and the nasolacrimal duct, which drains tears from the eye to the nose.

Lacrimal bones provide structure for the orbital cavity and support the eye. They also provide structural support for the lacrimal system.  

Associated Conditions

The lacrimal bone is extremely fragile and fractures can result from blunt force trauma to the face, especially those to the nose and eye.

Because of their proximity to the nasal cavity and the brain, fractures of the lacrimal bone can obstruct air passage and potentially cause damage to the brain. Sometimes lacrimal bone fractures can tear the lacrimal ducts.

Orbital fractures are diagnosed by examining eye pressure, X-ray images, and sometimes a computed tomography (CT scan). Careful attention must be made to elevated eye pressure, which can lead to nerve damage and blindness. An ophthalmologist may be involved if the trauma resulted in vision or eye motion damage.

Nasolacrimal ducts, which sit next to the lacrimal bones, can sometimes become blocked. Blocked tear ducts may be the result of health conditions, trauma, or infection. Symptoms include tearing and discharge from the eye.

Treatment

Fractures of the lacrimal bone may heal on their own or require surgical intervention. Maxillofacial surgeons handle surgical repairs to the face, including those to the lacrimal bones.

If a bone is merely cracked, surgical intervention may not be necessary. If, however, during the trauma, the bones broke and moved, surgical repair is required. Tears to the nasolacrimal duct may need to be surgically repaired as well.

Lacrimal bones are commonly replaced and re-attached with wire to surrounding bones. Surgery may be done by making a small incision at the corner of the eye or through endoscopy, where instruments and cameras are threaded through the nose or mouth.

While your bones heal, it will be important to avoid blowing your nose. Nose blowing might spread infection into surrounding tissues from the fractured bone. A decongestant may help during this time.

Blocked tear ducts may respond to warm compresses, massage, and antibiotics. If the problem does not respond to at-home treatment, you may require further intervention, like dilation of the nasolacrimal duct or dacryocystorhinostomy (DCR), surgery to make a new tear duct.

Prior to a DCR, you may have a CT scan or magnetic resonance imaging (MRI) so that your healthcare provider can get a closer look at your nasal passages. DCR may be done under local or general anesthesia.

During the surgery, a small incision is made between the eye and the nose and then a small hole is made in the bone beneath, which creates a new passageway. Sometimes this passageway is held open with a stent.