| Affiliation |
(AGL) Chairman, Department of Ophthalmology, The Methodist Hospital, Houston, Texas; Professor of Ophthalmology, Weill Cornell Medicine, New York City, New York; (EM) Class of 2023, Baylor College of Medicine, Houston, Texas |
| Transcript |
So we are going to be talking about retina versus neuro-op. Of course, neuro-op is better, but sometimes we get referred retina cases masquerading as neuro-op. And the reason is the two patient populations are quite similar. So, a prototype patient might be a 20-year-old, previously healthy, white female. And her complaint is going to be decreased vision. She may or may not have a little RAPD, and we might have a normal fundus. And so this stem, acute unilateral loss of vision, RAPD, pain without movement, and a normal fundus in a 20 year-old white female that is the stem for optic neuritis. And the most common cause: multiple sclerosis. But, sometimes its idiopathic. But what if we just add in a few little things? This stem would convert from a neuro-op case to a retina case. And so, differentiating these two is going to require symptoms and signs and then tests. So, what are the symptoms that would suggest that this is retina and not neuro-op? All of these are going to be the same. But one of the key things that separates optic neuropathy from retina is photopsias. Now, photopsias can occur in optic neuritis, but if the predominant complaint is flashing lights that's kind of a retina thing. Flashing lights. In addition, they might say its worse at night-nyctalopia-or, its worse in the day, hemeralopia. So, if we have hemeralopia or nyctalopia, day blindness or night blindness, those are really symptoms that match with the retinal photoreceptors because the retina does not really care that much whether it is day or night. But the rods and the cones care whether it's day or night. In addition, as a post optic neuritis, which normally produces a central scotoma or nerve fiber layer defect because it matches the pattern of the nerve fiber layer, retinal problems cause paracentral scotomas that look like a shape of a ring and we call that a ring scotoma. And that is because the parafoveal area with the macula and then the parafoveal area and with the fovea and the dead center is the foveal umbo. When retinal disease likes to affect the parafoveal area. So that means it might spare the acuity and a ring scotoma and then spread to the periphery. So, when we have a ring scotoma that is a sign that maybe this is a retinal problem. And finally, the fundus is normal because some retina problems are occult, and the prototype is an acute zonal occult outer retinopathy and its called an occult because the fundus is normal. We don't see anything. New innovations have occurred that allow to see the retina at a micron level however, and that is called OCT. So whenever we have a normal fundus, we are gonna do an OCT not only of the optic nerve, but of the macula. Because, what we're gonna be looking for in that OCT of the macula, is each of the layers in the layer cake from the retina nerve fiber layer to the retinal ganglion cell layer all the inner layers, the middle layers, and the outer layer. Because, even though acute zonal occult outer retinopathy is what I would call all of these normal fundus people. Now that without ST, we know that some of these zonal retinopathies are actually the inner retina or the middle retina and some are still the outer retina. An OCT can tell us where the hyperreflectivity is and where the thinning is in inner middle and outer maculopathies. And so, retina has named these like this acute middle maculopathy, or it might be inter maculopathy or outer maculopathy depending on where we see the problem with OCT. And ultimately, we sometimes have to do electrophysiology to confirm that the retina looks normal but isn't normal and that's a multifocal lenergy. So the electrophysiologic study will show that the ERG is decreased but only in the middle so we would not be using full field flash ERG in this setting. Multifocal is what we use for the center of vision. So, in this 20-year-old white female who has lost some vision and RIPD and a normal fundus-yes it could be an optic neuritis. Yes, we're gonna do an MRI looking for demyelinating plaque of MS. But, what if there are predominant symptoms of retina: photopsia, nyctalopia, hemeralopia, a ring scotoma, and we are going to deploy the OCT if we see that pathology on the OCT in the inner middle or outer macula? We might conform that that is an MERG and now this case goes from being neuro-op to being retina. |
