Swelling of the optic disc, the area on the light-sensitive retina where the optic nerve enters the eye
When the eye sends a signal to the brain, the signal travels along the optic nerve. The point on the light-sensitive retina where the optic nerve enters the eye is known as the optic disc, which can swell if pressure inside the skull increases. This condition is called papilloedema or optic disc oedema. There are several causes, including raised blood pressure (see Hypertension), head injuries, a brain tumour, or inflammation of the membranes that surround the brain (see Meningitis). The disorder itself does not cause pain, but the raised pressure of blood inside the head often causes headaches and vomiting.
Papilloedema is diagnosed with an instrument called an ophthalmoscope (see Ophthalmoscopy). MRI or CT scanning may be used to look for an underlying cause of the disorder. In the meantime, corticosteroids may be given to reduce pressure in the skull and prevent lasting damage to the optic nerve.
From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.