Ischaemic Optic Neuropathy

Ischaemic optic neuropathy refers to a condition in which blood supply to the optic nerve is affected, leading to visual loss due to a “stroke” of the optic nerve. It is one of the major causes of blindness or severely impaired vision among the middle-aged and elderly population. It may be classified into non-arteritic or arteritic causes.

Non-arteritic ischaemic optic neuropathy (NAION) is most commonly related to risk factors such as diabetes, high blood pressure, high cholesterol or smoking. It is the second most common neuro-ophthalmologic condition encountered in Singapore.

For every 10 cases, four may show some visual recovery over time, three may experience visual worsening while the remaining three may retain the same vision. There is currently no specific treatment, other than controlling the underlying vascular risk factors. The risk to the other eye has been estimated to be approximately 15% to 20% within five years.

Arteritic ischaemic optic neuropathy (AION) is primarily due to an immune condition known as giant cell arteritis – rarely occurring in Singapore compared to the Western world. In this condition, 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.

Patients typically complain of sudden onset of painless visual loss in the affected eye, which is often noticed upon waking up in the morning. Classically, the upper or lower half of the visual field may be affected more severely.

If there are associated symptoms of jaw pain, headache over the temple area, scalp pain or weight loss, seek urgent treatment as giant cell arteritis may be the cause of visual loss.

Normal optic nerve head

Optic nerve head in a patient with NAION

Currently, there is no proven effective therapy for NAION or prevention of fellow eye involvement, although we advise good control of existing risk factors.