Occlusion of the arterial blood supply leads to death of part or all of the retina. Occlusion may occur where the central retinal artery enters the eye on the optic disc (central retinal artery occlusion), or where branching of the smaller vessels occurs on the retina (branch retinal artery occlusion). Occlusion is usually due to particles of atherosclerosis breaking off from the large arteries of the neck and passing up to lodge in the smaller vessels of the eye. Rarely it may follow particles breaking off from the heart, from inflammation of the blood vessels in the eye (eg giant cell arteritis), from migraine or from very high pressures within the eye (eg acute glaucoma).
Clinical Features
Sudden painless loss of vision in one eye
May be complete loss of all vision or only a segment of vision such as upper or lower half or just a quadrant
May be preceded by episodes of transient loss of vision that recovered fully (amaurosis fugax)
