Blood supply of the optic nerve head and its role in optic atrophy, glaucoma, and oedema of the optic disc

Abstract

In the normal optic disc in man, the blood supply to the lamina cribrosa and the prelaminar regions is derived from the ciliary circulation, and that to the surface nerve fibre layer is a part of the retinal circulation. Fluorescence of the normal optic disc in fluorescence fundus angiography is greatest during the arteriovenous phase of the transit of the dye. The intensity of redness of the disc and of its fluorescence has a different distribution in 70 per cent. of cases. The fluorescence patterns of optic atrophies due to different causes are described. The fluorescence of the disc is reduced in these cases. Acute elevation of the intraocular pressure in monkeys selectively obliterates the vessels of choroidal origin in the optic disc and the peripapillary choroid; there is also reduced filling of the rest of the choroid but without any obliteration of the retinal vasculature. The role of choroidal circulation in the pathogenesis of visual field defects, optic disc changes, and cavernous degeneration of the optic nerve in glaucoma is discussed. Studies in patients with oedema of the optic disc suggest that the oedema precedes the vascular changes in the optic disc and the adjoining retina. The role of the ciliary circulation in the pathogenesis of oedema of the optic disc of different origins is discussed.