Ischaemic Optic Neuropathy refers to a condition in which blood supply to the optic nerve is affected, leading to visual loss. It is one of the major causes of blindness or severely impaired vision among the middle-aged and elderly population. It is most commonly related to risk factors such as diabetes, high blood pressure, high cholesterol or smoking (“non-arteritic” ischaemic optic neuropathy) although in some cases, it may be caused by inflammation of the blood vessels ("arteritic" ischaemic optic neuropathy).

The arteritic subtype - which is primarily due to an immune condition known as giant cell arteritis – is very rare in Singapore compared to the Western world. On the other hand, the non-arteritic form is the second commonest neuro-ophthalmologic condition encountered here. In the arteritic group, the risk to the other eye is very high, and once the diagnosis is made, steroid therapy is required to prevent loss of vision in the other eye. The risk to the other eye in non-arteritic cases has been estimated to be approximately 15% to 20% within 5 years.  Currently, there is no proven effective therapy for non-arteritic ischaemic optic neuropathy or prevention of fellow eye involvement, although we advise good control of existing risk factors.

In non-arteritic ischaemic optic neuropathy (NAION), patients typically complain of sudden onset of painless visual loss in the affected eye, most often noticed upon waking up in the morning. Classically, the upper or lower half of the visual field may be affected more severely. Up to 40% of cases show some visual recovery over time, while 30% of patients may experience visual worsening and in 30% vision remains the same. If there are associated symptoms of jaw pain, headache over the temple area, scalp pain or weight loss, giant cell arteritis may be the cause of visual loss, and urgent treatment should be sought, for reasons outlined above.

Optic nerve head in a patient with NAION	Normal optic nerve head xxxxx

Please visit the following relevant links :-

Neuro-Ophthalmology Service
Neuro-Ophthalmology Clinical Staff
I Want an Eye Examination / an Appointment
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