Anterior Ischaemic Optic Neuropathy
Ischaemic Optic Neuropathy occurs when there is poor blood flow to the optic nerve. It is the most common cause of sudden decreased vision in the over fifties.
What is Anterior Ischaemic Optic Neuropathy?
Ischaemic Optic Neuropathy (ION) is a sudden loss of central and/or side vision because of poor blood flow to the optic nerve (the information ‘wire’ from the eye to the brain). It is the most common cause of sudden decreased vision in patients older than 50 years. It is usually not related to other illness although may be more common in people with diabetes or high blood pressure.
What causes Anterior Ischaemic Optic Neuropathy?
It is not clear what causes the loss of blood supply to the optic nerve. These episodes may occur when there is a sudden drop in blood pressure (following an operation or with blood loss after an accident). Patients who smoke, or who have diabetes or high blood pressure, may be at a higher risk for ION.
What are the symptoms?
Sudden loss of central or side vision (especially the lower half) is the most common symptom of ION. Vision loss is usually at its worst when first noticed, and in most eyes permanently remains at this level.
How is it diagnosed?
A medical eye exam is performed, including measuring your visual acuity, testing how your pupil reacts to light and examining the back of your eye. A visual field test may also be performed.
How is it treated?
At this time there is no effective treatment for ION. In people with central visual loss, up to 40% of patients may improve their central vision over time, though visual field problems are unlikely to recover. It has been suggested that Aspirin and vitamin supplements may decrease the chance of an episode in the opposite eye.
FREQUENTLY ASKED QUESTIONS
What did I do to make this happen?
In most cases, there is nothing you or anyone else did to create this problem. The anatomy of your optic nerve is what you were born with. It is possible that smoking and high blood pressure may have increased your risk. Ultimately, we still do not understand the trigger that will produce the ischaemic event.
Will my vision get worse?
Within the first few days or weeks, worsening is possible though this is uncommon. To reduce this risk stop smoking and make sure that your blood pressure is adequately but not overly aggressively controlled.
Will my vision get better?
In patients with central loss, there is a 40% chance of improvement although the visual field tends to remain the same.
How can I prevent involvement of the other eye?
Taking 75mg of Aspirin a day and vitamin supplements may reduce the chances. Avoiding cigarette smoke and proper treatment of elevated blood pressure may also help.
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