| Identifier |
Blood_Supply_of_the_Optic_Nerve |
| Title |
Blood Supply of the Optic Nerve |
| Creator |
Andrew G. Lee, MD; Jenny Ren |
| Affiliation |
(AGL) Chairman, Department of Ophthalmology, The Methodist Hospital, Houston, Texas; Professor of Ophthalmology, Weill Cornell Medicine, New York City, New York; (JR) Class of 2022, Baylor College of Medicine, Houston, Texas |
| Subject |
Blood Supply; Optic Nerve; Ischemia |
| Description |
Dr. Lee lectures medical students on blood supply to the optic nerve. |
| Transcript |
About how knowledge of the blood supply to the optic nerve can help us understand ischemic events in the eye and in the optic nerve. And, so, the ophthalmic artery obviously supplies the eye itself and the central retinal artery. So when the ophthalmic enters into the orbit, the central retinal artery penetrates the sheath and then passes into the eye and gives off the branches in the retina - the superior temporal and the inferior temporal branch retinal arteries. So these branch retinal arteries arise from the center retinal artery, and on its way out the central retinal artery supplies part of the optic nerve head itself. The ophthalmic, however, also supplies the posterior ciliary artery circulation, and the posterior ciliary artery can have a variable number of posterior ciliaries (very small arteries), and those supply the optic nerve as well as have the posterior circulation which is in the choroid. So when we have arterial occlusive disease that affects the eye, if we have a central retinal artery occlusion, a CRAO, that will block the flow of blood into the central retinal artery, and what we see is lack of perfusion in the retina that will cause retinal whitening. But because the choroid is still being perfused from the ophthalmic, that produces a distinctive ophthalmoscopic finding called a "cherry red spot." And the reason it's cherry red is because the rest of the retina has become ischemic and opaque, and we can see through the very thin fovia - the fovia is like this because all the elements are displaced - so what we can see right down into the fovea to the choroid. And so when we see a cherry red spot we are actually looking at the choroidal blood flow accentuated by the ischemia caused in the central retinal artery distribution and making an opaque and white retina. So if we see a retinal opacity and we don't see the cherry red spot, that's one of the clues that the patient's occlusion might be more proximal and affecting both the central retinal artery as well as the choroid and that means it's more likely to be ophthalmic. It also might indicate that it's vasculitis. In an elderly patient you might be thinking about giant cell arteritis. And this kind of patient who has no cherry red spot might be no light perception vision because they have an ophthalmic artery occlusion. At the level of the disc head, a posterior ciliary artery is the presumed cause of anterior ischemic optic neuropathy, both of the arteritic type and the non-arteritic type of anterior ischemic optic neuropathy. And so when we have giant cell arteritis and vasculitis, it has a predilection for these posterior ciliary arteries, and if we have an occlusion, either a thrombus or vasculitis in this location, it'll cause a swollen disc, and that is arteritic anterior ischemic optic neuropathy. However, nocturnal or other hypotension and hypoperfusion in the same distribution is what is thought to produce non-arteritic anterior ischemic optic neuropathy. Both are anterior because they're anterior to lamina cribrosa and cause disc edema. Both are ischemic optic neuropathies because the problem is at the disc head. And the only difference is arteritic, i.e. giant cell, versus non-arteritic, and that is a blood supply problem at the optic nerve head itself. And if you have a problem with the posterior optic nerve from ischemia, also ophthalmic level distribution, that we don't call AION, we call that PION because the ischemia is behind the globe, behind the lamina cribrosa. So when we're looking at the blood supply of the optic nerve, we're really looking at posterior ciliary circulation. In the retina we're looking at central retinal artery. There are branches of the ophthalmic. We can have CRAO, BRAO, AION, either arteritic or non-arteritic, and we can have PION - posterior ischemic optic neuropathy. And so knowledge of the vascular supply to the optic nerve helps us understand ischemic events that occur in the eye. |
| Date |
2020-06-22 |
| Language |
eng |
| Format |
video/mp4 |
| Type |
Image/MovingImage |
| Collection |
Neuro-Ophthalmology Virtual Education Library: Andrew G. Lee Collection: https://novel.utah.edu/Lee/ |
| Publisher |
North American Neuro-Ophthalmology Society |
| Holding Institution |
Spencer S. Eccles Health Sciences Library, University of Utah |
| Rights Management |
Copyright 2019. For further information regarding the rights to this collection, please visit: https://NOVEL.utah.edu/about/copyright |
| ARK |
ark:/87278/s6d27h0s |
| Setname |
ehsl_novel_lee |
| ID |
1578873 |
| Reference URL |
https://collections.lib.utah.edu/ark:/87278/s6d27h0s |
