| Transcript |
"So today I want to tell you about retinal correspondence in terms of neuro-ophthalmology. Even though this is kind of a pediatric ophthalmology concept, you need to know a little bit about it in neuro-op because these patients sometimes end up in neuro-op clinic as adults. So, as you know, the two eyes have a fovea that is going to be looking at the target, and those foveae have to correspond. So, normally the two foveae correspond to the exact same point in space, and that is normal retinal correspondence. And normal retinal correspondence is normal. However, we have the abnormal version of it, which is anomalous retinal correspondence. And the anomalous word means not only is it abnormal, but it's somehow helping the person. And the reason you have this is because the corresponding point the fovea has either been moved because of strabismus or some other reason why the fovea is not in the right place. But, if it happens in a kid before the maturation process in the cortex has occurred, you can create a corresponding point in your retina that isn't the original fovea. And so, in a patient who has strabismus, normally they have diplopia. But in a patient with anomalous retinal correspondence, they can have strabismus, their eyes crossed, but because the fovea is not corresponding to the fovea in the other eye, another spot is, then you can have strabismus with no diplopia. And what that means is if this person were to come to the adult clinic and they have a clear strabismus, but they have no diplopia, and each eye is normal 20 20 acuity. Then, we would not want to straighten this eye out. Because if you straightened it out, then they'd get diplopia. Even if their complaint is "I don't like the way it looks." In addition, we can get points that don't correspond as an acquired phenomenon, after the maturation as a kid, and that can cause diplopia in someone on an efferent basis or an afferent basis. And that is a difficult concept to understand. So when you have a clearly retinal problem, like an epi-retinal membrane, or you have a subretinal neovascular membrane from age-related macular degeneration, that can pull the fovea off its off its center. So, if the fovea moves, then you'll have disruption in the foveation of one eye compared to the other eye, and that means you'll no longer have normal retinal correspondence. So, this person here where their fovea is pulled by the epiretinal membrane, or the subretinal membrane is pulling their fovea a little bit off, the two retina do not correspond anymore, and so you'll have diplopia, binocular diplopia, not monocular diplopia, and it'll be from the retina. So the way this comes to me is the person has some sort of retinal problem, epiretinal membrane, AMD, something like that, and they're complaining about binocular diploma. So, then the retina doctor says well it's binocular diplopia, it goes away if I cover either eye. And they're going to say therefore it's not the retina and that's going to get referred to neuro-op, or it might make a stop off at strabismus. At strabismus, they put the prism on, and if they put the prism on it'll align the foveae. But then the periphery won't be aligned, so they still have diplopia. So they won't be able to fix this strabismus, because it you'll have central versus peripheral rivalry, and that peripheral versus central rivalry is created by the fovea is no longer being on corresponding points. This is going to be very hard to fix, the peripheral fusion is way stronger too, and so you're not going to be able to get this person to fuse. So, you need to know a little bit about retinal correspondence, both the normal version and the anomalous version, in the kid form as well as in the acquired adult form where the fovea is moved. This comes to neuro-op as diplopia in patients who have afferent disease or no diplopia in patients who clearly have a strabismus or efferent disease." |
