Ischaemic
optic neuropathy (ION) is the commonest adult optic nerve disorder encountered
worldwide and can be expected to increase in incidence in our ageing
population. The condition has been classified as a) anterior (AION) affecting the optic nerve head and b) posterior (PION) involving that portion of the
optic nerve behind its immediate retrolaminar portion. Furthermore there are
two pathological varieties of the disease c) Arteritic (AAION) almost
exclusively associated with Giant Cell Arteritis (GCA) and d) Non arteritic
(NA-AION or less correctly NAION) usually associated with diabetes,
hypertension and hyper cholesterol laemia. A recent treatise on the subject
runs to more than 600 pages.
