The Optic Nerve Head
Here all the nerves that make up the retinal 'net' gather
together and leave the eye in a bunch, bound for the brain.
The retinal 'net' does not exist over this disc of optic nerve, so a blind area, corresponding to the size of this disc, is present in each eye.
Inspection of the optic disc is very useful in diagnosis:
The retinal 'net' does not exist over this disc of optic nerve, so a blind area, corresponding to the size of this disc, is present in each eye.
Inspection of the optic disc is very useful in diagnosis:
- Pressure within the skull (from a haemorrhage within the brain, or
a tumour) will cause this disc to bulge forward.
- In Glaucoma, pressure from within the eye squeezes off the blood supply (like standing on a garden hose); a reduced supply starves the retina of nourishment, and its nerve cells start to die. A regular eye examination is one of the best safeguards in in the early diagnosis of this condition.
Photo below by permission of the Internet Ophthalmology Society
This is the appearance of an optic disc in a person with glaucoma. Pressure within the eye has given it a 'hollowed out' appearance.
| Blood Vessels | Fovea | Eyelid |