| Affiliation |
(AGL) Chairman, Department of Ophthalmology, The Methodist Hospital, Houston, Texas; Professor of Ophthalmology, Weill Cornell Medicine, New York City, New York; (EL) Class of 2023, Baylor College of Medicine, Houston, Texas |
| Transcript |
Today we're going to talk about a few entopic phenomena. ‘En" means in,‘ optho' means eye. These phenomena arise from inside your eye. You need to know about them because they're very strange complaints often and you could mistake the patient for being non-organic if you don't know but what to listen for. The easy ones are floaters, so like a posterior vitreous detachment of PVD. Especially when you have a detachment off of the disc itself and make a round detachment and that is often called the Weiss ring. But anybody who has any kind of vitreous debris when the light comes in, that debris will cast a shadow onto the retina and will produce a floater. So, the patient will say ‘I see something floating in my vision.' It usually moves with their eye movement, and it'll go away if they close their eyes, because the light can't hit the debris and cast a shadow. You should also know that we have traction, either vitro macular traction or vitro papillary traction, where the vitreous itself is pulling up either on the macula or pulling up on the optic nerve. So that pulling up is traction and that traction on the retina can activate the retina and so patients might see flashes of light. So, this traction doesn't have to be in the macula, it can be in the periphery and that can lead to a retinal detachment and that's why patients who have flashers and floaters, you really have to do an exam on them to make sure it's not a PVD traction or retinal detachment. So those are the easy entoptic phenomenon, the ones that are more difficult are blue field entoptic phenomenon and as you can imagine it's called blue field because patients often see it when there's a completely blue background and the most common is the blue sky. So, when they're looking up at the blue sky they see dots, and those dots are the white blood cells, and those blood cells are moving and so to the patient it will look like a series of little dots just moving in their visual field. It'll be bilateral, simultaneous, they're small, they're stereotyped, and it will happen every time the patient looks. So, they'll be reproducible so they can keep reproducing it over and over again. The other one that you might want to know about is called the Purkinje tree, and as you know in the back of your eye, you really can't see your own blood vessels so here's the optic nerve, but really the light is hitting that blood vessel and you can't see it but your brain just suppresses that image and makes it go away. But if we do in direct ophthalmoscope on this patient where you're shining a very bright light on them, and you can do this on yourself or on your colleagues, they will see the image of their retinal vasculature as an after image, and that we call the Purkinje tree phenomenon. So, you need to know about flashers, floaters, the blue field entoptic phenomenon, and the Purkinje Tree. There's another one called the Haidinger's brush, which you don't have to know about too much, but is a polarizing effect from the differences in the wavelength and the appearance of the macula. That one patients don't ever complain about because it requires light polarization. So, these entoptic phenomena are super common, they sound crazy, but they're not crazy and they're from in your eye, entoptic. |
