Friday, October 21, 2005

Retinal Blood Supply

Ultimately the retina derives its blood supply from the ophthalmic artery. The outer retina is supplied from the choriocapillaries. The inner retina is supplied from the distribution of the central retinal artery.
The central retinal artery is a branch of the ophthalmic artery that begins about 4 mm posterior to the optic nerve head. The branch enters the optic nerve to become central within the optic nerve and divides to 2 main branches in the optic nerve. The vessels further divide to supply each quadrant of the eye with an artery and a vein. In about 20 of individuals there are cilioretinal arteries derived from the choroidal circulation that in some individual may supply the macula alone.

The central retinal artery is a small muscular artery with fenestrated elastic lamina. retinal arterioles, do not have an internal elastic lamina and upon penetration of the retina do not have smooth muscle cells.

Retinal blood vessels maintain the blood-retinal barrier (similar to the blood-brain barrier). The endothelium is non-fenestrated and do not permit leakage of fluorescein.


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