| Identifier |
Lateral_Geniculate_Field_Defects_Lee |
| Title |
Lateral Geniculate Field Defects |
| Creator |
Andrew G. Lee, MD |
| Affiliation |
(AGL) Chairman, Department of Ophthalmology, The Methodist Hospital, Houston, Texas; Professor of Ophthalmology, Weill Cornell Medicine, New York City, New York |
| Subject |
Geniculate; Sector-anopia |
| Description |
Dr. Lee lectures medical students on field defects. |
| Transcript |
"And how this can produce very specific types of visual field defects that you need to recognize. So as you know, we're looking at the visual pathway, the eyeballs, the optic nerve, the [optic] chiasm, the optic tract, the geniculate body, and then the radiations. It is this location (Lateral geniculate body) that we're going to be talking about today. So the anatomy of this lateral geniculate body is very strange and so the blood supply to the geniculate body has a very interesting configuration and it corresponds with the type of visual field defect that we see. So this whole medial part of the geniculate body has a different blood supply than the lateral parts. And so when we're seeing a visual field from a geniculate lesion, we might see a very strange configuration of the homonymous hemianopsia. So obviously it's going to be [a] retro-chiasmal lesion, [it] is going to produce a homonymous hemianopsia on the contralateral side. And so normally you're used to seeing homonymous hemianopsias that look like this. However, in geniculate lesions, because of this blood supply orientation, you might see a field effect that is a wedge to fixation, and that wedge sector-anopia kind of looks like pac-man. So it's like a right homonymous wedge sector-anopia and that results from involvement of this same wedge inside of the geniculate body. So the blood supply to the geniculate body here might involve just the lateral choroidal artery and that involvement of the lateral choroidal artery knocks out the wedge of fixation and spares the top part and the bottom part of the visual field. Conversely, if you are involving the anterior choroidal artery circulation, anterior choroidal, so if you're involving the anterior choroidal artery circulation, you'll get a homonymous hemianopsia; but instead of involving that wedge, you'll have this sparing of the wedge. And so in Goldmann fields, it might look something like this, where you have the top and the bottom knocked out but there's this sparing of the field. And so if we see pac-man type field, you really should be thinking about sparing and involvement of that wedge and we call that a wedge sector-anopia. It doesn't absolutely localize to the geniculate body because occipital lobe lesions can do the same thing, but it's highly suggestive of it. And sometimes there are metabolic lesions that knock out both geniculates at the same time. And those field defects are very characteristic and very unusual looking because it'll produce this kind of like hourglass looking thing where you have a bilateral juxtaposed homonymous wedge sector-anopias. So if you see an hourglass field, that's really going to be like a lateral geniculate body lesion that's bilateral and it's going to be in both eyes. And if you see pac-man that's also a geniculate field. So any variation of pac-man or hourglass wedge sector-anopia or sparing of the wedge you should pick genic[ulate]. " |
| Date |
2022-03 |
| 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/s6p3h7nj |
| Setname |
ehsl_novel_lee |
| ID |
1751082 |
| Reference URL |
https://collections.lib.utah.edu/ark:/87278/s6p3h7nj |
