Anatomy and regulation of the optic nerve blood flow

The arterial supply to the optic nerve has been widely investigated; however, the precise anatomy of the anterior optic nerve microvasculature remains difficult to ascertain. Detailed assessment of this anatomy is limited by its small vessel caliber, its complex three-dimensional structure, and the relative inaccessibility of the microvascular bed. The major branches of the ophthalmic artery include vessels to each of the extraocular muscles, the central retinal artery (CRA), and the posterior ciliary arteries (PCAs). The CRA and the short PCAs provide the blood supply to the optic nerve head. The evaluation of ocular hemodynamics continues to improve with the development of new imaging technologies. The article summarizes the vascular anatomy of the optic nerve head (ONH), retina and choroid, the regulation of blood flow in the optic nerve head, and several imaging techniques used to measure blood flow in the eye.