Optic-Nerve Swelling (Papilledema)

What Is It?

Papilledema is the swelling of the optic nerve as it enters the back of the eye. When you have a headache or unexplained nausea and vomiting, your doctor will look into your eye with an ophthalmoscope. This handheld instrument shines a bright light into your eye. Changes in the appearance of the optic nerve and the blood vessels that pass through it can be seen through the ophthalmoscope and might be related to the source of your symptoms.

The anatomy of the optic nerve makes it a sensitive marker for problems inside the brain. This nerve is a thick cord that connects the back of each eyeball and its retina to the brain. In its short span between the brain and the eye, the optic nerve's whole surface is bathed in cerebral spinal fluid. This fluid protects the nerve from sudden movement. However, even slight increases in the pressure of this fluid, from swelling of the brain, can compress the optic nerve around its whole circumference in a "choking" manner. When this nerve is exposed to high pressure, or when it develops inflammation on its own, it can bulge into the back wall of the eyeball, resulting in papilledema.

Some important causes of increased pressure from cerebral spinal fluid and papilledema are brain tumors and brain infections, such as a brain abscess, meningitis or encephalitis. Eighty percent of people who are diagnosed with brain tumors have some evidence of papilledema. A pressure increase resulting from bleeding or from very high blood pressure also can cause papilledema.

One condition can cause increased pressure in the cerebral spinal fluid without associated swelling of the brain or ventricles. This condition, called pseudotumor cerebri or benign intracranial hypertension, results from an overproduction of spinal fluid. It is more common in women who are obese and of childbearing age. The condition seems to be triggered at times that the body is adjusting to hormone changes, such as pregnancy, the start of birth-control pills, the first menstrual period or menopause. The name pseudotumor was given to this condition because it results in symptoms identical to those caused by a tumor in the brain, and causes classic papilledema.

Symptoms

Symptoms related to papilledema are caused by the increased pressure and include headache and nausea with vomiting. Twenty-five percent of people with advanced papilledema also will develop some visual symptoms. Typically, the visual changes are recurring brief episodes lasting less than 30 seconds in which the vision turns gray or blacks, sometimes described as if a veil has fallen over the eyes. The symptoms usually affect both eyes at once. Visual blackouts often are triggered by a change in position, such as by standing up very suddenly, or they may be triggered by coughing or straining within the chest or abdomen. Occasionally, people with papilledema can have an experience of flashing lights, often seen in an arc shape. Other visual changes occur over time, including a smaller field of vision with a larger blind spot and, ultimately, blindness, if successful treatment is not given.