Ischaemic optic neuropathy in chronic simple glaucoma.

The characteristic visual field changes of early glaucoma occur in the Bjerrum area of the visual field and are related to damage of the arcuate nerve fibre bundles (Traquair, 1944; Harrington, i964a). The susceptibility of these nerve fibre bundles at the optic nerve head to functional changes, whether reversible, relative, or absolute, is the prime characteristic feature of the glaucomatous process, although it is not exclusive to this disease. A vascular cause for this damage has been postulated by many authors (DukeElder, I962; Gafner and Goldmann, I955; Harrington, 1959; Feldman, Sweeney, and Drance, I969), but in some instances a metabolic derangement of the neurone may influence its susceptibility to damage from reduction in blood supply (Armaly, 1969). In previous communications we have described an acute ischaemic change in the optic nerve head characterized by a symptomless haemorrhage on a sector of the disc and a corresponding fresh absolute arcuate scotoma, a sequence of events hitherto not described in chronic simple glaucoma and probably of considerable importance in the natural history of the disease (Drance and Begg, I970; Begg, Drance, and Sweeney, 1970). The present report amplifies the concept of ischaemic optic neuropathy in the glaucomatous process and shows that it can be responsible in some eyes for the conversion of ocular hypertension to chronic simple glaucoma.