Acquired Hyperopic Shifts

Hello, welcome to my eyes for ears. You're off the malls, you know, a cab's board of view podcasts, where your host Ben Young. - And Amanda Redfern. - Each week could take a high-o'-talk topic and talk about the wine, how. What are we talking about this week, Amanda? - So in continuing our little trend with the Oral Board's prep, we were gonna talk about a hyper-optic shift today. - Again, these episodes are gonna be on the quicker side. It's really to help you with Oral Board of View specifically and help give you those high yield things that you need to remember if you get into a case, that's hyper-optic shift. So keeping with that, we will go through the differential and just like our previous episode, we're gonna do it in an organized manner to try to help everyone keep it in the brain. So we'll start anterior to posterior. Minicutals about the differential for the things most anterior. - So I started off with the cornea and by far in a way, the most common would be dry eyes and having those little dry spots on your cornea causing a hyper-optic shift in the refraction. This is typically going to be small, but significant. And then the next thing I think about is any flattening of the cornea that might come from other causes like contact lens wear can do that to you. You can also have overcorrection from refractive surgery. So getting that history is important. And of course, you can't forget along those lines, the old RK surgeries after a time that effect wears off and they start to have flattening of their cornea, which is really frustrating. And if you talk to these patients, they actually are pretty disappointed that they made that decision way back then. And then another thing to think about is any loss of tissue from any prior corneal injury such as an ulcer. - The next thing to think about is the lens. So there's a couple ways that the lens can give you an hyper-optic shift. One is just straight a fakia. The natural lens on average gives you plus 20 diopters of refraction. So if it drops out of view, traumaticly or from a condition like a topial lintis where your zygosmic weak and then would drop, then you could get a plus 20 fraction. One might think that that would be fairly obvious, but there are certain unusual situations where it may not be very noticeable to a patient. Just to give an example, I had a patient once who was extremely myopic, but then one day, notice her vision got a lot better and then didn't think anything about it. And then another whole lens dropped and they went from being minus like 18 or something to Plano and they were delighted. - It's like that Spider-Man effect. Do you remember the little Toby McGuire when he puts on his glasses his glory, he takes it off and it's clear? - Exactly. - Like Sam Rape was simulating a fakia. - Either your lens fell to the back of your eye or you got bit by a radioactive spider. - That's it, yeah, that's in the next thing in the differential, thanks for spoiling it. Bit by a radioactive spider. And then the other thing in terms of lens, besides you know, fakia or a topial lintis where the lens might shift in position to like if your sounds weak for some reason that ships it can also give you a hyperopic shift, is decrease a combinative tone. So some reasons for that can include pharmacologic effects. 80s people can make it more difficult for your lens to accommodate. Or you can just have natural loss of accommodation, including over time that can manifest as latent hyperopia. So think about reasons that you may not be accommodating as much or that I may be forced to not accommodate as much as causes of this hyperopic shift. - I hate to take vitreous causes away from you because this is totally up your alley, but that silicon oil that you put in people's eyes. - Uh-huh. - Hyperopic shift. - It can give you a hyperopic shift. - So it's a little bit complicated of a reason what may never come back to this in another episode. It's a little complicated of a reason why silicon oil, which is a higher refractive index, makes you hyperopic in a fake egg eye. It was like interesting math to in terms of curvature because a patient is fake egg, but just remember if someone has silicon oil placed in their eye, then in general make them hyperopic after fake egg. And at the opposite they're a fake egg. Okay. - But at least the retina's attached. - At least the retina's attached in that case, which brings us to retinal causes of hyperopia, which maybe the, so corneus may be the most common reason, but retina reasons may be the most important reason. So if your retina is being pushed more anteriorly, if it's being pushed more forward, you're gonna have a relatively shorter axial length which will give you an apparent hyperopic shift. Resist for that include macular edema. So that might be fairly common of say someone had cataract surgery was doing well, then they end up with a hyperopic shift. It could be because of macular edema from something like Irvine gas syndrome. And that means that at the post-op month one, you shouldn't give them their hyperopic, refraction, you should do an OCT and think about, do they be true with drops to fly in their macula? The other, and this is like one of the two that like, I think they're gonna need you to know to be able to pass a question of hyperopic shift is a choroidal mass. Basically any mass that's under the retina, whether it's in the choroid or in the orbit, can push the retina forward and give you a hyperopic shift. So those are like, they do not messes up. It could be tumor that could kill someone or cause a vision loss that would otherwise been maybe been preventable. And that's what we have for this episode. I mean, do you wanna give us a summary of the reasons that we talked about one more time? - Okay, so going from front to back, you have multiple reasons for corneal causes of hyperopic shifts, including dry eyes, any sort of flattening of the cordia from scars, contact lens use, prior refractive surgeries. On the lens side, which is the next, you can think about losing your lens or having your lens being displaced or changes in your accommodative tone. From the vitreous, you can have silicone oil in fake eyes, causing hyperopic shifts. And then with the retina and globe, anything that's pushing the back of your eye forward can lead to a hyperopic shift. - Yeah, if you like what you heard, you can follow us on Twitter at eyes, four years, number four, or leave us a review if you'd like to hear more of this kind of episode on iTunes or wherever you found our podcast. We'll see you guys next week. Bye. - Bye. (gentle music)