Ischaemic optic neuropathy (ION) is the commonest adult optic neuropathy encountered in Southeast Asia and will increase in incidence with an ageing population. It occurs in two forms: arteritic and non-arteritic. The latter variety being by far the commoner encountered in the region and presenting as an anterior optic neuropathy with optic disc swelling. The clinical presentation of both varieties is described with particular reference to the hyperaemic disc appearance of the non-arteritic disease as opposed to the ischaemic, pale, swollen, infarcted disc seen in arteritic anterior ION. Essential visual field defects found in both varieties are emphasized; the prognosis and treatment are discussed. Pathological specimens are also illustrated. Posterior ION is briefly mentioned being a diagnosis of exclusion.
The anatomy, especially the blood supply of the optic nerve head, is discussed along with its role in the production of the different varieties of ION.
Key words: Optic neuropathy, ischaemia, optic disc swelling, ciliary arterial circulation, pathology.