Optic Nerve Swelling (Papilledema)
What Is It?
Papilledema is the swelling of the optic nerve as it enters the back of the eye due to raised intracranial pressure. Fluid surrounding the brain is constantly produced and reabsorbed, maintaining just enough intracranial pressure to help protect the brain if there is blunt head trauma.
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, causing papilledema.