Pathophysiology of Glaucomatous Optic Neuropathy: Role of Optic Nerve Head Vascular Insufficiency

Abstract

In 1970, based on my experimental and clinical studies, I defined glaucoma as: “a disease wherein the normal balance between the intraocular pressure and the blood pressure in the choroidal vessels supplying the optic disc and retrolaminar part of the optic nerve is disturbed, resulting in vascular insufficiency in the optic disc and retrolaminar part of the optic nerve, and hence in visual field defects and pathological changes in the optic disc and optic nerve.”1 Since the conventional wisdom at that time was that glaucoma was essentially mechanical in nature, caused solely by high intraocular pressure (IOP), this concept was received with marked skepticism. Since then, however, evidence that vascular insufficiency in the optic nerve head (ONH) plays an important role in pathogenesis of glaucomatous optic neuropathy has progressively accumulated; so that now its vasogenic origin is widely accepted.2 To understand the vasogenic mechanism of glaucomatous optic neuropathy, it is crucial to have a good understanding of the following: 1. Blood supply of the ONH. 2. The various factors that influence the ONH circulation. 3. Evaluation of the ONH circulation.