Anatomy of the Nasociliary Nerve

The nasociliary nerve is a sensory nerve in the eye. It is part of the ophthalmic nerve. The nasociliary nerve provides sensory information to the cornea, eyelids, and the cells of the nasal cavity.

The nasociliary nerve is often involved in nasal pain. Nasal pain is rare and can happen spontaneously, as a result of injury, or as a side effect of surgery on the nose.

Anatomy

The nasociliary nerve is one of the three main branches of the ophthalmic nerve (the other two being the frontal nerve and the lacrimal nerve). It lies between the two divisions of the oculomotor nerve. It comes into the intracranial space just below the ethmoid bone, which is located in the center of the skull between the eyes.

The nasociliary nerve divides into the communicating branch, the ciliary nerves, the infratrochlear nerve, the posterior ethmoidal nerve, and the anterior ethmoidal nerve. As it extends to the anterior ethmoidal nerve, it passes through the middle and anterior cranial fossa, the orbit, nasal cavity, and the exterior of the nose. 

Anatomical differences in the nerve may include branching variations, including missing branches.

Function

The nasociliary nerve provides sensory perception to the cornea, eyelids, conjunctiva, and cells and mucous membranes of the nasal cavity. Its function is exclusively sensory, with no motor function.

The ophthalmic nerve, of which the nasociliary nerve branches, networks with the eye’s motor nerves. 

Associated Conditions

Damage of the nasociliary nerve can result in dysfunction of the eye and nasal pain. While nasal pain is rare, when it happens, it can be difficult to diagnose.

Charlin’s Syndrome

Nasal pain usually occurs immediately following injury, but it can also occur long after. Because of the many nerves and the intricate branching of the nasal and ophthalmic nerves, diagnosis of the origin of nasal pain can be tricky.

Nasal pain that originates from the nasociliary nerve can result as a complication from rhinoplasty (nose surgery). The procedure can sometimes result in irritation or damage of the nerve.

Sometimes a painful neuroma of the nerve stump can result in a condition called Charlin`s syndrome (also called nasal neuralgia). Charlin’s syndrome is characterized by head, facial, and eye pain, as well as severe nasal discharge and congestion.

Diagnosis of nasal pain and/or Charlin’s syndrome involves detective work. Discussing where the pain is located, how the pain behaves, and how frequently it occurs are all clues that can indicate the origin of the problem.

Your healthcare provider may order magnetic resonance imaging (MRI) and computerized tomography (CT scan) to get a better look at your brain and sinuses.

Corneal Ulcer

A corneal ulcer can irritate ophthalmic nerves, including the nasociliary nerve. A corneal ulcer is a sore on the cornea that is often caused by infection.

Infections in the cornea may result from wearing contacts too long or placing contacts with bacteria into the eye. They can also occur as a complication of herpes simplex and from infections introduced by eye injuries.

Symptoms of an ulcer may include redness, pain, discharge, vision changes, and itching. Early diagnosis is important. Left untreated, corneal ulcers can lead to blindness.

Diagnosis may involve a slit-lamp exam, which uses a microscope and bright light that allows your healthcare provider to more closely view the structures of the eye and cornea. Your healthcare provider may also perform a biopsy on a small piece of tissue from the cornea.

Rehabilitation

One way to test the integrity of the nasociliary nerve is to test the corneal reflex. When the ophthalmic nerves are functioning normally, both eyes should blink when either cornea is irritated. If the eyes do not blink, then the nasociliary nerve may be damaged.

Corneal ulcers are most often treated with antibiotic, antiviral, or antifungal medications. Sometimes steroid drops are used to reduce inflammation. In extreme cases, a corneal transplant, which involves removing part of the cornea and replacing it with healthy corneal tissue, may be recommended.

Treatment of nasal pain associated with nerve damage or Charlin’s syndrome is very rare. As such, there is not a lot of evidence of successful treatment in the scientific literature. Some people respond to tricyclic antidepressants, nerve blockers, and local anesthetic.