Optic nerve atrophy is the death of fibres in the nerve that connects the eye to the brain. This results in visual problems ranging from mild blurring to total sight loss, depending on the extent of the damage.
Second cranial nerve atrophy, optic neuropathy
Many factors can lead to optic atrophy. In some cases there is no known cause.
The condition may be congenital (present at birth):
- This is usually hereditary - a genetic condition in which the optic nerve in one or both eyes does not develop correctly.
- Optic atrophy may also be caused by oxygen deprivation during pregnancy, childbirth or in early infancy.
- Certain drugs taken during pregnancy may also give rise to atrophy.
Optic nerve atrophy may also be acquired (not genetic), usually through problems with the blood supply to the eye or nerve. This form of the condition usually affects elderly patients.
Other causes of acquired optic nerve atrophy include:
- Inflammation or swelling of the optic nerve
- Pressure against the optic nerve (for instance, from a tumour)
- Damage to the optic nerve from shock, trauma or radiation
- Toxins such as methanol, tobacco and other poisons
- Diseases of the eye, especially glaucoma, in which the pressure inside the eye is too high
- Disorders of the central nervous system, for instance cranial arteritis, multiple sclerosis, stroke and brain tumours
- Vitamin B12 deficiency
- Paget's disease
- Blurred, dimmed, or lost vision in one or both eyes
- Loss of ability to see fine detail
- Reduction in field of vision, and distorted vision to the side
- Distorted colour vision
- Weak constriction of the pupil in reaction to light
- Involuntary eye movement (associated with some congenital optic nerve atrophy)
An ophthalmologist can confirm these symptoms with various eye tests.
Where the nerve enters the back of the eye, it looks like a small disc, which can be examined with an ophthalmoscope. The disc will be pale or white in colour if nerve fibres have been lost due to optic atrophy.
Damage to the optic nerve fibres is irreversible: there is no treatment that can restore lost or reduced vision. However, if the condition is diagnosed early, and the underlying cause is identified, it may be possible to prevent further damage. Treatment will be specific to the underlying disease or problem that has caused the atrophy.
There will always be some permanent loss of sight, whether mild or severe. At worst this may lead to blindness, at best it may be halted when the symptoms are still slight.
Complications will be specific to the underlying cause of the atrophy.
When to call your doctor
If you experience any of the listed symptoms, or any change in vision, you should contact an eye specialist urgently. If optic nerve atrophy is diagnosed, it should be closely monitored by an ophthalmologist.
A few of the causes of optic nerve atrophy may be avoided:
- Safety precautions (such as seat belts in cars) can prevent injuries to the face and eyes.
- Home-brewed alcohol containing methanol, the most common optic nerve poison, should be avoided.
- Good control of diabetes mellitus
- Vitamin supplements in cases of vitamin B deficiency
- Glaucoma management should be optimal.
Reviewed by Dr M J Labuschagne M.B.Ch.B, M Med(Ophth), (OSSA member), University of the Free State, November 2010