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Okie Dokie. Let's get going. Thanks for waiting guys. I hope you can all see the slides and see me and at least hear me. Um uh today's session will be led by myself Wesley, um and my colleague, um Atif who's in Reddit is currently helping um just to moderate and just to help me manage the tech. Um So today, we're covering um visual pathways, visual fields, defects and then a bit about the eye exam. Um It'll be a fairly fast paced session, so hopefully won't use up the whole hour, but it's also gonna be interactive. Um There's only a few folk here today and there's honestly no judgment. So if you've um if we ask a question um that you can pop an answer to the into the chat, then please do. Um They're mainly fairly easy questions. So you won't have to think too much in terms of um is this gonna be this or is it something else? It'll probably be quite an obvious answer for most of the questions and then we'll also have a few Mc Qs to run through. Um So it's not like going through the learning outcomes. Um So today, hopefully by the end of the session, you'll be able to understand what a visual pathway is and how it works. Recall common visual field defects with the anatomical location, conduct a fairly basic eye examination one that will see you through UK MLA and then also through foundation um and then interpret eye exam findings to consider possible differential diagnoses. So we'll start off with the structure of the eye exam. Um The things that you've probably all heard, heard of before. So we usually start by looking at the eye. So general observation, um checking the visual acuity of the eye, um checking visual fields, then looking at the pupils, um making sure to check for relative afferent pupillary defect. And then sometimes we do cover testing, then we test the muscles of the eye with what some people call the H test. And then if you're lucky to have a fundoscope, uh you can do fundoscopy. So we'll start by talking about visual acuity first. Um When you're on the wards, often they don't have a Snellen chart. Um So if you have an Android phone, you can use the app called Peak Acuity. If you've got an iphone, you can use Ola check, they're free apps pretty easy to use and they tell you how to do the test. Um II use the check all the time. Um And you basically just sit at the end of the bed about 3 m from the patient and you click through and um the patient can read the letters and then you can click whether it's 123 incorrect or all correct and it'll take you through and then it will tell you um what the visual acuity is. So visual acuity is, it's important to test at both distance and near. Um Sometimes people use the no OD and OSO D is right. Um OS is left and they usually use a Snellen chart, um which is the one that we've got on the right. Um And it's usually done at 6 m. Um So for example, if someone had 660 vision uh in here, um the top, the top number is uh the patient to chart distance. So it's 6 m and the denominator of the bottom number is the line that the patient can read. So, on this chart, that would be a um for most of us, it'd probably be the line that says six U AZ and F DT. Um If you're looking at American stuff, it's often in feet. So 6 m would be 20 ft and then so 66 is 2020. Um And I put a wee note here about pinholes. Um So when you're testing, patient, patients visual acuity, you'll usually use it with glasses, but sometimes people don't have glasses and they actually do need glasses. So if you can use a pinhole that can quickly test whether they have any refractive error that can be corrected if their va improves the pinhole, that probably means they have a refractive error. If their eyesight is so bad that they can't use the silon chart. So they can't read a, then you'd probably be thinking about the um acronyms at the bottom. So it would be counting fingers, hand movements, only perception of light or no perception of light at all. So um those are some acronyms that you can consider using. Um We come on to confrontational visual fields. I'm sure you've all done this as part of your neurological examination. So in the picture that we've got here, you can see the guy on the left is testing the guy on the right. So he's testing his left eye vision. So it's important to test each eye one at a time. It's a quick screening tool. Um It's for very gross uh visual field defects. There's more specialized equipment that you can use if you want to look to closely map visual field defects change over time. But that's not the kind of thing that we'd probably use in the ward. Um And I'm just like the neurologist, like to say visual field defects are all about localizing lesions. So, thinking about at what level, um there's AAA problem that's causing the defect that we're seeing. So we'll start off with our first question. Um And I'll pull up a wee poll so that you guys can vote. Um I don't think the poll. Um. Mhm. The poll tells anyone who's voted for whatever. So, I'll let you guys, I'll give you a minute to, um, read the questions and then you can vote smashing stuff. Um, so we've got a few votes for optic chiasm and a few votes for optic radiations. Um, so the answer is optic chiasm. Um, the questions worded a bit weirdly but, um, uh, in the last line you where it says, and finally, it does not have any peripheral vision in either eye, you'll be thinking about uh bitemporal hemiopia. Um So that leads us to visual field defects. I'm sure you've all seen a lovely chart like this before. I'm afraid this is the only one that could find that didn't have some form of copyright on it. Um So that's the one we're stuck with. Um So on the left, we have the chart which shows the visual pathway. So you'll see the eyeballs um leading down to the optic nerve to the optic chiasm, then the optic tract leading to the lateral canulate nucleus, then going to the radiations and the cortex. Um The important thing to remember is that everything's flipped. Um So nasal fibers mean they carry the temporal field. So if you're looking at the chart on the left, um you'll see that for the right eye. So looking at the green triangles, the darker green is the nasal field and it translates to temporal fibers. Um there's two other things to note. Um If you have a patient who has a central visual field defect, it's probably likely to be um macular. And if they have something that sounds like tunnel vision and it's longer standing, that's probably something like glaucoma. Um And the final tip just before we move on would be that um if you look at points um images five and six, if there's central sparing, so the central vision is not affected, then it's likely to be something in the o on the occipital cortex. Um That's a lot of information. So what we'll do is we'll break it down, we'll break down the diagram into two parts. So first we'll look at the top half. Um So in number one, so looking at the right eye, which doesn't have any sight, so left eye is fine, right eye is not affect, is, is affected. Um We can see that that's at 0.1. So looking from the top going down, you can see that the eyeball is fine and then you have a cut at the optic nerve. So that would cause a ipsilateral um visual um monocular visual loss. And then you get to the chiasm which causes the bitemporal hem inopia. And then once you're past the chiasm, then things are no longer ipsilateral, they're contralateral. So they affect the opposite side. So at 0.3 which is the right optic tract, we see that the visual defect whilst the, the the anatomical lesions on the right, the visual defects on the left. And that's the ho hemin. Okey dokey. Now we go on to the second part which is um post chasm, post tract. So, after the lateral geniculate nucleus, we have um part four which has a upper quadra anopia. Um and then five and six, they correlate. Um So if you think back to what we were saying just then about uh central sparing being an occipital lesion. So both of those um one's upper and one's lower, they have central sparing. Um So they're probably going to be occipital uh lesions as opposed to, if they were further up, they wouldn't have central sparing. So like 0.4 that's further up, that's in the radiations. Um That's the, the central vision is affected. Okie Dokie. Um that was a whistle spot, a whistle stop tour through the visual field defects. So now we'll just go into the eye exam. This will be fairly fast paced and if you uh listen along, er then it, I would love if you could pop er in the chat, what you think is going on, it should be pretty easy. Um So for example, this eye is normal, you don't need to put anything in the text, but the next few will have images which show a pretty obvious lesion or something that's wrong and if you can just pop in an answer and then we can move on as quickly as possible to the next part. And obviously, as Atavist said, there's no silly questions, there's no silly answers, just pop an answer in and then we can, we can all learn together. So, um, this is an example of a pretty common pathology. So we have a patient with an injected eye and it looks like there's some purulent stuff just at the lower l lower eyelid. Does anyone have a ha hazard? A guess what this might be smashing stuff? Perfect dear. Exactly. So conjunctivitis. Um Are you feeling brave enough to say why you think it's bacterial over viral purulent discharge? Amazing. Top 10 marked you get 100% and past med. Perfect. Let's go. Um So conjunctivitis as DEA said, and we'll go to the next patient. Um This one could be uh one of two things, scleritis. Nice Amanda. Yeah. And um if uh so it could be scleritis or it could be episcleritis doesn't have any ideas as to what we would use to differentiate the two presence of pain smashing 10 out of 10 Amanda. That's perfect. So this is an image of episcleritis. I mean, I can only tell because the person who's taking the photo has told it has has named it episcleritis. I but um the pain is usually the thing in the question stem that gives it away. Sweet. Then we come to our second question and I'll give you a minute to go through this and we'll pop a pole up. Okie Dokie. That's a minute. So we've got quite a wee spread of um, answers for the M CQ. That's, um, I think that's, that's pretty, pretty accurate. Um So you're, you've assessed the patient. Um, you've done the right thing. You've already diagnosed him with herpes zoster ophthalmicus and you referred him urgently to ophthalmology. Um The answer is actually orally cyclovir. Um So, oh, someone's changed their answer. Um But 40% of you answer that correctly. Um The key differentiator obviously is oral ver is topical ayr. So that cuts out the remaining four. It's kind of confusing because there's a few options in terms of chlorphenol steroids and oral steroids. But the main thing is this guy's got something that's affecting not only the area around his eye, but also his eye and he really does need urgent ophthalmology um review and then oral acyclovir, they might choose to add oral steroids later on. But that'd probably be a decision that um ophthalmology would take. Um This is an example of trigeminal herpes with uveitis, keratitis. I suppose an example of something that could be really, really bad. Um And for extra points, sometimes question stems will talk about uh rash on the tip of the nose or the side of the nose. Um and sometimes called Hutchison sign which indicates necessary involvement and possible ocular involvement. Ok. Dokey. Um So for our next photo, um we've got something going on with the eyelid. Does wanna have a hazard. A guess what might be going on if you don't know the, the, the term or the specific name you can just say and kind of lay and speak what you, what you think is going on. Does the lower eyelid look normal? Does it look like it's sagging or? It's ectropion? Sweet. Perfect. It is. It is. Um, so sorry if I completely butchered your name, um is exactly right. It's an ectropion. So it's an eyelid that's sagging and it's going outwards. So it's an ectropion as opposed to one that where the eyelashes would brush the inner of the eye coming inwards, that would be an entropion 10 out of 10. Um And we have an image here of a scaly looking eye. Um, probably an upper eyelid. Does anyone have a gue have a guess as to what might be going on? What kind of condition this person might be having? I can get a bit more detail just while people are thinking. Um So this patient might have uh sort of watery eye kind of allergic type symptoms. And commonly the advice would be lit hygiene. Okey dokey in the interest of time, I will give the answer this time. Um So this is blepharitis, specifically anterior blepharitis. Um And does anyone have to uh does anyone want to give it a go as to what might be going on in this patient's eye glazing? Good good, close, close. Um, so it could be either either a sty or Chian. This one is an external stye, um, nice Janet. Um, so styes are usually um staph aureus infections. They can either be internal or external. If they're internal. They affect the Mabo gland. If they're external, they affect the glands of xy or gland of mole. Management's fairly simple. It's usually hot, compress analgesia and you only ever need to give topical antibiotics usually if there's associated conjunctivitis. So this is a sty um You can see it's got a, a yellow point, eyelid looks quite red by comparison. Uh This is a Chalian. Um So a Chalian is a retention cyst, usually the Maian gland, it's usually firm and painless. Um compared to this dye, which looks quite red and has that yellow point, often good job guys. Um And this is uh just I think one of the last photos we have of the eyelid is a typical BCC. So you get all sorts of skin lesions around the eye. Um This is not a terribly great example, but you can see there's a bit of a pearly rolled edge and a bit of central depression or ulceration. Okie Dokie. Now on to our third question. Ok. Okie Dokey. Um So most of the people, most of the people have said, right, optic neuritis and they're absolutely light, right? Absolutely light. Absolutely. Right. Um So you have the 43 year old woman. She's got headaches and you've got all this chat and then you notice that when you shine your light in the right eye, her right pupil dilates. But then when you shine the light in the left, both pupils constrict. Um, so you can see that the left eye is working both sides, but it seems to be working correct because both eyes constrict, both pupils constrict, but on the right, there's the defect. So, um, looking at these examples, it's fairly easy to cut out the left options and completely easy with the right options. And then we'd be thinking about a right ent pupillary defect called, um caused by a right optic neuritis. And that leads us to our next bit just before we go over rapid. Um, we'll talk a bit about pupils just looking at this photo. Can anyone has a guess as to what's going on? Anything that's overtly obvious? Sorry, I should clarify purely descriptive. So you don't need to say what you think is the underlying diagnosis or anything, but just looking at her eyes, this patient's eyes, what do you think you can see? Aoria? Amazing Amanda. Yeah. So as Amanda's currently highlighted, Aoria is a difference in the size of the pupils. So as part of your eye exam, you'll be looking at the smashing K is exactly right, right, pupil dilated left constricted. So you'd be looking at the size, the shape, um and then the symmetry. So um shape looks normal in both size is quite varied. And then they're asymmetrical as both a man and Fiona have uh, correctly pointed out. And that brings us on to pupillary reflexes. So there's quite a few. So there's direct consensual and then Swinging light which is testing both the R APD and then there's also accommodation. So this is just a wee summary of the papillary light reflex pathway in some ways, it's helpful in some ways. It's probably not very helpful. It complicates it a wee bit. But if we just look at one of the sides, so if we look at the right side, you have light that enters the retina, it's carried by the optic nerve, then it goes to the pretectal nucleus. And then, so that's the afferent pathway. So the sensation, so light coming in going down the optic nerve um and then you go to the pretectal and then you'll see there's some fibers that stay on the same side, on the right and then there's the green line that goes to the other side. Um And that happens to both sides and, and then they go to the eating a Westphal nucleus, then to oculomotor and the spill sphincter, which actually then ends up constricting. So the going from the top to the bottom, um looking at the right eye where you see number two, that's the afferent pathway and then going down, then it's efferent, but you'll see that it requires both sides working to have an effective response. So, thinking back to our patient, the 43 year old with headaches who had um uh afferent pathway that worked on both sides, but an efferent that didn't on the other. Um And I put a wee sore at the Scottish flag here because um the R APD pupil is sometimes called a Marcus Gunn pupil. And Marcus Gun was Scottish. This is another way of just describing or pointing out what the R APD looks like. So it's chronological, going from the top to the bottom, we have uh one circle for the right eye, one circle for the left eye and the black circle is the pupil. So going to the second line, if you shine a light in the right eye, the right pupil dilates um that's the direct uh and then the left pupil also dilates. So in this, in the second line, we can see that not only the afferent pathway, so sensation uh works, but the efferent in both works. So both pupils are constricting, which is normal. Then what you can see is that when you shine the light in the left, the left and right eyes, um they, they, they, they don't constrict. So there's loss of the afferent pathway. Um And then when you shine the light back to the right, again, the afferent pathway is working and both eyes constrict, efferent is working in both eyes too. And that leads us to the fourth question. Wow, you guys absolutely smashed that. I think that was too easy of a question. Everyone knew it was horned straight away. Um, and 90% have said left. Um, which is absolutely correct. So, the woman has a, um, left eye, which is more droopy than the right. And then the left eye is also smaller, left pupil is also smaller than the right. Um, for bonus points. Is there a third sign that you might expect to see for someone with Horners lack of sweatings? Absolutely anidrosis. Well, everyone's just typing. Just that seems to be amazing. Thanks Janet, thanks, Amanda and thanks Fiona. That's perfect. OK, dokey. And that leads us to um kind of the latter half of our um eye exam. So this is fairly er niche but it can be helpful. So cover testing. Um This image has a prism on the left um which is covering the right eye. You don't need to worry about that. But on the covering the left eye, which is on the right of our image, the black circle that's performing the cover testing, cover testing is quite an easy way to think about uh whether there's a um some form of strabismus, it can differentiate tropia and four. But essentially, the easy way to remember is if you cover the fixating eye, um then and then the other eye moves, then there's probably going to be strabismus. Um That's probably all you need to know for UK M. But if you want to know more, there's also more information that can also differentiate more things that leads us to our fifth question. It's smashing stuff. So everyone's very sure it's a third nerve palsy, which is absolutely right. And most people have said a right third nerve palsy, which is correct. Um So you have that typical, first of all, um the, the, the right eye is affected and it's more down and out than the left, um which is uh due to oblique and rectus work um that brings us on to the extract, the movements and the muscles. This is a fairly complex diagram with, with a lot going on. But we'll start by looking at the left which is looking at a right eye from the outside. So from the temple, looking in, there's quite a few muscles. The top muscle is the one that is used for your um eyelids. Um And then going down, you have the superior bleak, which has an attachment, which is why it has a slightly angled um uh it can pull in an angled fashion and then you have the superior rectus, you have the um lateral and medial rectus. And then at the bottom, you have the inferior rectus and looking in the right part of the diagram. Um This just summarizes the different types of movements. Um Easy way to remember is the up and down left to right is usually mainly the rectus muscles, the names correlate. So medial rectus SPS, medially, lateral rectus, laterally, superior and inferior, obviously. Um and then inferior and superior oblique, they go at an angle at oblique angles and they also have some action going up and down too, that brings us almost to the end. Um So when you finish, when you're finishing your exam, you'd want to do fundoscopy if you can, this is an example is a normal eye. So looking at the center, at the dark kind of center, you can see the macular and the FVE and then slightly to the left of the diagram of the photo, you can see the optic nerve with the retinal vasculature coming out. It's a normal eye. So there's no cupping or anything like that. And finally, um if you were doing um fundoscopy, it's usually to exclude papilledema. Does anyone want a pretty easy question? But does anyone want to uh mention what might cause papilledema? High cp smashing stuff, Amanda. Absolutely. So quite a few different things can cause it. Um So things like tumors, high BP um but high ACP is the main main mechanism. Yeah. Okey dokey. Um So just to finish off, we've got three more questions there from the um original visual field pathway um diagram, but I've just popped the eyes. So um we'll start off with this one. So if you could just select where the defect is or where you think it is. Okey dokey. I think that's almost everyone that's written. So, um, if you wrote right optic nerve, you're correct. So everyone's correctly identified as the optic nerve that's affected. So, if I take us back to the slide with the diagram, um I should have clarified, sorry, the side that's blue is the side that you're not seeing. So if that's the reason that you've done left instead of right, then you're absolutely right. If you were thinking that the left eye is affected and you put left optic nerve, that's correct. Um Going back to what we were talking about just at the beginning, sorry, there's a lot of information, but the, if it's affecting one eye monocular field, vision loss, it, it's gonna be the optic nerve. Um and in terms of left versus right, anything that's pre chiasm will be ipsilateral. So it will affect the side that the lesions on anything post chiasm is going to affect the side, the other side, the contralateral side. Um So for the next question, it OK. Okie Dokie smashing. So everyone's in the right ballpark here. They're all thinking about radiations. That's absolutely correct. Um And it's definitely right, there's also only right option. Um And most of the people have put uh right temporal radiation, which is absolutely correct. Um So the easy way or I try and remember it is um we're thinking it's a radiation because it's um doesn't have macular, it doesn't have central sparing. So, it's unlikely to be something that's in the occipital cortex. Um It's right because it's affecting the left side. Um and it's probably temporal because everything slipped. So if you think temporal lobe is lower parietal lobe is higher, it's affecting the up. So it's probably the lower part temporal radiation is absolutely correct. And last one just to finish. OK. Smashing stuff ending on a high note, 100% from 100 100% of the people. It's definitely optic chiasm. I think that's all we have today. If you have any questions, um, feel free to pop them in the chat, we'll probably be here for a few minutes or so. Um, otherwise we look forward to seeing you at our next session, um, which we'll be posting in due time and it'll probably be a rapid review. So it'll be a whole bunch of, um, MC Qs going through photos of uh common eye things, um, and just, uh high