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Palsy. All right. That's got in session two. We have section three and in case anybody wonder this is the Durham Chapel. OK. We have a questions here, any answers from the audience? Sorry, I know it's very long presentations. All right, we've got one answer so far more. OK. So the actually is actually e squamous lung, cell, lung cancer. So what happen is when the light is dim, the right people dilate but the left does not and that is nor normal and the left eyelid is droopy. So what you have, you, you got meiosis eye that doesn't dilate and you got droopy eyelid steatosis. So that is should be something that rings a Bell Horners syndrome and Horner's syndrome love panels too. You know, the the the medical school love pancoast tumor at the medical school, state level. A lot of things actually cause Horners Syndrome. But at your level, all you need to know is pancoast tumor, tumors of the lung at the apex of the lung. So right, just like just right beneath your clavicle. You know, if there's tumors like around the area pressing on the sympathetic nerves, that's what caused Horners Syndrome. Sorry. No, no. Um the parasympathetic system raise the eyelid. Um that's uh fire the oculomotor nerve. If it's lesions, then you got full ptosis. Like oddly enough, this is one area where the sympathetic system and the parasympathetic system do not oppose each other. Um The sympathetic system also raise eyelid up but not as strong as the parasympathetic system does. So if you have Horners syndromes where the sympathetic nerve is damaged, you got partial ptosis only in the pupil. On the other hand, there is a opposite action. So you've got the sympathetic system because it's fight or flight. So when you are running away from your enemy, you want to see as far as possible, you do not need to accommodate. So you do not need to, you know, squeeze down your eyes and really concentrate and make your people small. So what happen is your people go really large? So you've got mydriasis. Now, if you have a parasympathetic response, which is when you can sit down, relax, have a cup of tea, eat something and read a book, then your eyes need to be small people. People, sorry, your people need to be small so that you can look at and focus on the near object of the book. So you got meiosis. That's a parasympathetic system. The parasympathetic system is innervated by the ocular motor nerve. The CN three, the sympathetic system is just sympathetic system for now, it cause mydriasis. Now it's hard to remember. Meiosis versus mydriasis. So I got a little memory a as well there. Meiosis means small bio a biography is a book. So a book is smaller. So meiosis is in smaller people, mydriasis. On the other hand, is a big driver, you know, driver is a person. So obviously a person is bigger than a book. So it's much bigger. That's how I remember it, the efferent and Effient pathway. Um what I want you to know is, um, you need to know the order and sequence. They definitely gonna test you on it for the purpose of the pupil uh directions. You know, it doesn't go to the normal like genicular nuclei. You see when you try to see something and you need higher brain processing, it has to go through the thalamus to the L GN and then goes through to the s the lobe and so forth and so forth. But for the case of, um, check, you know, getting the pupil size, you don't actually go to L GN, you go to a structure called pretectal area, which is still inside your midbrain. It's not the thalamus. And that protective a area actually feeds to both the left and the right. So let's say the left also goes to the right as well, the adding west nucleus, the ewn and that's why you got consensual response. And then this is the classic pictures about the rep relative afer pupillary defect. Everybody's so confused about. Um you can look at the pictures, showing the stuff, but I actually made a nice little analysis to help you memorize the difference between Afer versus EF defect and how to tell the difference. So the Afer people defect, you shine a light at the defective eye. Both eyes dilate. That's because the Aphron heart is defective. So you do not get the signal at all that there were even was a light shining in front of that defective eye. But then if you shine the eyes and the nonaffected eye, both eyes can constrict because they know that there's a light there that the the the unaffected side has intact pathway. So going back to this. So let's say if the person has left atrial pli defect, you shine a light to the right side, both pupils constrict because the right pathway still can feed the signal back to the the brain. Say, hey, you know what? There is a light, let's constrict, the pupils and both pupils got the signals to the m the muscle part part, the motor part is a non affective. Now you shine the light to the left side. On the other hand, the left side does not get the signal input. So both pupils dilate because they don't even know there was a light going signal going to the brain because they couldn't be the the the the pathway is blown. Ok? Now, if it's an EHR problem, then only the defective eyes stay dilated, whether you're shining whichever eyes that you're looking at. So you can see if it's an Afer problem, both eyes will work the same way. Whereas if it's an e problem, only one eye is affected and that's the defective eye, the other eye is fine. It won't do anything to the constrictions or dilations of. It makes sense if that helps you to uh distinguish the two. Any questions so far? Um Sorry, it's a little long. People seem to have problems understanding this concept. So I wanna make sure that everybody can nail it. Any questions. Any you can email me later, I guess if you're shy or if you want me to explain it again, I can do that. OK. So, all right. So why do we care about our APD? Why does the medical school make you to understand this concept? The swing light and the relatively afferent papi defect are they just statistic uh could be? But for me, as an ophthalmologist trainee, this is important because R APD indicate the cost of mono Muar vision loss. So later on when we do clinical reasoning, you know, in the later sections, when you have vision loss, it's very important to do the R ABPD test if the R APD test actually positive. So you do find a problem with the afferent pathway that could only mean two things. One thing is your retina com, a huge part of the retina is damaged. So that limits your option to something like CR O crv O or retinal detachment. RD, CRV O retinal vein occlusion, cr AO central retinal arterial occlusions. So that's one possibility. The other possibility is there's optic nerve damage. So, but this damage, then that means your, the pathway is feeding the the light signal back to from the eyes back to the brain is damaged and that signal is always carried by the optic nerve, right. So if the R APD is showing some problems with the afferent pathways, and you know, you can suspect the optic nerve might be problematic too. So that leaves you with few options, you know, uh things like, you know, giant cell arteritis, GCA optic neuropathy, just a fancy way of saying disease of the optic nerve or N IO N non arterial ischemic optic neuropathy. So that brings us to section four on the visual field. This is something that I'm not gonna do well, too much on because I think the anatomy sessions always do a very good job of it. Um This is something that you can get from geeky medics or whatnot. Um Make sure you do know the the the reasoning behind it. If you have problem, please email me, I can explain it in detail. Um The main thing is if you have bitemporal hemiopia, so be here and usually there's only two types of defects. You either have a tumor in the pituitary gland or craniopharyngioma, which is also a type of tumor around the pituitary area that's pressing on the optic chiasm. Um And then also the other thing, some people like the acronym pits when it comes to those uh quadrantanopia understanding. So if the parietal lobe is affected, then because the parietal lobe is on the upper side of the brain. So your eyes is funny, your the brain in, in the eye, the retina part, the part of the retina and the brain involved in looking at things. It's always looking opposite. So the brain and the eyes in on the top half, it only looks at the bottom half and the bottom half of the brain in the retina will looks at the superior, the upper half of things. So you got this nice little acronym pits to help you and the occipital lobe has dual circulations that other circulation questions again. So that's why you got macular sparing because the part that received the signal from the macular um that part is so important that even the area processing it has two blood supply. So you got the posterior cerebral artery that supply the back of the brain, that's the usual. But if that has some problem like a stroke or something, then you also have a backup called middle cerebral artery that also supply the area that process the signal from the macular. OK. So this is the other questions um for you guys give it a try the answer from the audience. OK. We got D your answer is T so this is the type of stuff they have on S AP for you, for a visual field. For this one sections, usually there is one S ap question and one SDA questions. Um So the key part is that the persons um have problems with right, superior quadrant. So the right S right quadrant goes to the left side of the brain. So that's the left and then the superior half will correspond to the bottom half of the brain. So that's the temporal lobe. And the thing that gives even more detail away is the nonsensical speech, speech part because that's the part of the brain that what you call um uh the weick aphasia. So that's why you can still speak. But you're worthy as Wordsworth by the British author um you already as Wordsworth, but it's not making sense to me. So that's how I remember it on the temporal lobe of the dominant side. So if you're right handed, your dominant half of the brain will be the left half the left atmosphere and that will be um where the R as uh uh uh center will be located at. So that's also tied back to some of the concepts in case 20 as well. No, so very cool. Um OK. So that brings me to the end of uh section four which is a short one. Section five is the clinical reason. That's the way we always get the acute reasoning. Sorry, it's s ap um, so the red eye, the, there's a load of conditions almost a bit like, you know, collecting Pokemon cards and stuff and, you know, unless you're fanatic, II still don't get all the pikachu and vet carbs and all that stuff. So I try to make it as a systemic analysis as possible to make it easy to kind of work your way through rather than uh relying on rod memorization. So rule of thumb, if it's painful for the red eye, it's likely to be serious. Refer if this cause a loss of vision. It's also serious red flag. Go for a refe referral same day assessment, please. And the main thing other than pain and vision loss is you look at the pattern of the redness. Where does the redness come from? Now, the redness obviously come from some bold bulky dilated blood vessels, right? So where does the blood vessels coming from? There's only two patterns. One is the ciliary injection. Sometimes some will call ciliary flush. What that means is you see the the border between the sclera, the white part of the eyes and the clear part of the eyes, the cornea, right? The border is called the limbus. So if you have blood vessels coming out of that border from that limbus, that means usually something more serious. It's the inflammations of things inside the eyes. So things like cornea, things like ciliary body, things like um Iris, those are inside your eyes, those are probably will have ciliary flush. Now you got conjunctival injection. So we talk about stuff that's underneath the eyelet. So if, if the blood vessels coming underneath the eyelid and spare the border between the cornea and the sclera, that's what they call conjunctiva injection. That's likely to be less serious because it's more superficial. It's the conjunctiva that is being affected or the eyelid. So this is a very important concept to you for you to have to help you kinda navigate all these conditions. Another way to kind of navigate this list of long list of conditions is look at the anatomy going by step by step. So you got eyelids, the blepharis, you know, the colas and all that stuff. Those are probably not very serious. They are self aor painless, the conjunctiva, which is quite superficial as well. So that these are not terribly um serious. 11 that you might come across quite a bit is called subconjunctival hemorrhage. It comes on suddenly it's painless, it does not cause vision loss. So if it looks really dramatic, like the whole eyes are red, usually the redness come from the conjunctiva, come from the bottom eyelid and spare the limbus part of the area. So, you know, you might ask them about blood thinner use, but it's not something that is really worrisome at all. Now, you've got things like episclera and sclera. Now, when I started to have red there, that usually can indicate a condition that actually causes a significant amount of pain. And when I said earlier, if it causes pain, it's serious. And then cornea, whenever cornea is affected, it's always painful. Now, why is that the case? Because cornea has a lot of nerve endings, that's also explained the reason why behind cornea reflex, right? If it, there's not so many nerve endings, how do you know somebody's poking your eyes and you can just, you know, close your eyes instantaneously. You know, that's because there's a lot of nerve endings and when there's a lot of nerve endings, it's gonna cause pain. So keratitis, inflammation of the cornea, painful corneal abrasion, you know, just, you know, scratching the cornea surface, painful ulcers, scratching even deeper, even more painful. The other one is anterior chamber and angle. That's glaucoma. I would discuss that later on. So, stay tuned. Um The other one is if it affects iris and the vitreous, it will cause something called anterior uveitis, which is the inflammation of the uvea. And then also if you have a recent ocular surgery, ocular implant or anything that any injection or needle you jab into your eye, you got endophthalmitis, that's another cause of um red eye. Now, the thyroid eye disease is something I'm not gonna cover because it's not part of the curriculum, but it's something I listed as part of uh completion sake, conjunctiva, conjunctivitis. Uh People really want me to make notes of that. So uh I list made a table to tell, allow you to tell the difference between the t to free. So allergic start off is the one that always bilateral. It's always happened on both eyes at the same time, it comes up with watery discharge. So that's very important. Um And diffuse injection, it causes follicular. So it causes kind of bump. That's because those bumps are like little, you know, white lymphocytes that are aggregating to cause the havoc in the first way. So they got Folli follicles and those follicles are most obvious when you lift up your eyelid and then, you know, you see the, the bottom of your upper eyelid and you see a lot of little bumpy stuff and then allergy causes a lot of itchiness. And usually if you asked about history taking, you get histories of atopy things like a rhinitis or like hay fever or asthma viral also present very similarly. But viral usually happens with a viral cyst a disease beforehand. So usually they have some cough and cold before and that's, you know, leading up to that and the viral usually is a dany virus which is highly infectious and contagious. Now, the big question is to memorize the one for bacteria, bacterial is the one that is uh very distinctive from the others because it's purulent. It's very, very, lots of pus, lots of yellowish discharge. Whereas viral and allergic gives off watery discharge, bacteria always give a very pussy, very yellowish thick discharge and crusting. Um That's uh kind of an important thing to uh do. And also the unremitting discharge is especially too true when you have conjunctivitis that is caused by STD. So things like gonorrhea or chlamydia can cause very, very bad discharge. So bad that one clinician described to me is like saying if you've got a tissue paper to wipe off those discharge, three or five minutes later, the discharge will come back like a flood with a revenge. It's very, very um productive uh in terms of creating the this discharge, sorry. Um this is gonna be a little dry but I'm trying to make it as interesting as possible. Epi scleritis versus scleritis. So, episcia is just a spin layer of blood vessels supplying the sclera. So it's more superficial. So it's less serious when you have red eye like that. And what you can tell how you can tell between the two is because epi scleritis is mild pain. So no pain, almost no pain or if there is pain mild and it doesn't affect vision. And if you actually give them an eye drop like a constricting eye drops, it blows like the ri blood vessels will go away, will whiten up. Now, scleritis on the other hand is deep boring pain. It's like there's somebody drilling inside your head and it's especially worse at night, which makes it very obvious to patients. And you, it makes it very difficult to sleep. The pain will, will, will be worse when you move your eyes or being shine a bright light. So there's pain and then also there's reduced visual acuity. So you see less. Well, so now you've got two red flag symptoms in scleritis where you have none in episcleritis. And with cis, you can't just give an eye drop to blanch. It, it won't whiten up. It's because it's deeper structure, you can't just press on it and the blood vessels will go away. It doesn't, it actually comes up with a bluish hue on it. Both conditions are associated with systemic conditions and the systemic conditions. Both of them are most associated with a keyword, rheumatoid arthritis, keratitis is when the cornea become infected. There are two ways to do that in any history taking. If somebody tells you they wear contact lens, then you need to bring your gigantic red light up. It's a red alert sign because contact lens is very high risk for pseudomonas infections of the cornea. And in fact, it's sight threatening because the pseudomonas can drill through the cornea and really damage your eyesight. So it's really much a medical emergency. You really need to start getting antibody eye drops on top of that and start wearing the contacts. Um Usually it comes with a mucopurulent discharge. But if you, if your question mentioned contact lens. Think about bacterial keratitis. That's my go to for you at this stage. It won't make things too complicated. And then the virus, there are two types. One is not listed here, but the the common type is called herpes simplex virus. The simple way to to distinguish that is you got dendritic ulceration. So the scratch, the the the breakage in the cornea looks like a tree, like a Christmas tree. So that's what dendritic means. Um you got reduced corneal sensation. So actually, ironically with herpes simplex, you might get no eye pain at all, even though the eyes are really damaged, that's a bit unusual. The reason why is because the herpes simplifies, target the nerves. So actually damage the nerve. So you don't feel the pain, not because it's not causing damage. It's because it's damaging the nerve that's causing the pain signal in the first place. So nobody is nagging you about this problem because the person that's supposed to nag you by causing pain are dead, are killed by the virus. The other virus is common isoster virus. It's not listed in this table and then corneal abrasion whenever they mention corneal abrasion, really simple, drop some fluorescein dye t turn off the light in the room, turn on the blue light on the slit lamp and you see this beautiful picture. If everything is blue, then everything is intact. It's good with this person. It got a greenish tinge here. That's the site of the abrasion. If the, if the cornea has any breakage, it will turn to area green under fluorescein. When the, when the slit lamp is shining blue light on the eyes. Unfortunately, uveitis um cause red eye, but it cause red eye in a bad way. Um it cause eye pain, it cause photophobia. So pain is one and it cause decreased visual acuity that second ciliary flush. So that's what I was talking about because it's a inflammation of the uvea of the iris of the ciliary body. It's deeper, it causes blood vessels to dilate from the limbus area. And that's why I say whenever you have ciliary flush, take notes, it's serious, it's bad. Um you also have distorted pupils. So the pupil, well, this one looks pretty ok. But sometimes you got those really silly heart looking shaped pupil that you see sometimes on Instagram and stuff that might not be a good thing because uh usually that means something's wrong. The eyes would be, you know, in order for them to turn up round. But heart shaped um previous history is a is a key sign because uveitis happen quite recur quite a bit, quite frequently. So you could have previous history in your thing. And then also you have systemic disease. It's, you know, basically uveitis is like the rheumatology of the eyes. So you got a lot of rheumatology conditions like lupus, like um uh like uh rheumatoid arthritis or uh inflammatory bowel disease or um, you know, connective tissue disease that associated with uh manifested uveitis. Now, endophthalmitis is a long list, but I just want to make you know that any time if the person has a recent ocular surgery such as a cataract replacement or any sort of intraocular drug administrations or any sort of things that people jap into your eyes causing like, you know, do a surgery or giving drugs that could introduce foreign pathogen like bacteria inside your eyes. And when that happened, it cause very red eye as you can see there. But also you can get um painful, red, painful red and hypopyon. You see that yellow level water there. Those are not water, those are not tears, those are pus pooling on the ball of the eyes. That is not a good sign, it's a medical emergency. You definitely need to refer right away. Ok. This is not