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Hi guys. I'm going to talk to you a little bit today about wilderness ophthalmology. Um My name is Dan Morris and I work in the University Hospital Wales in Wales in Cardiff. So most people a bit apprehensive about treating eye problems either because they are bored by eyes or they're very squeamish and petrified by eyes. But it's fairly true to say that most people are not really very okay treating eye problems. Don't really understand how to deal with eye problems in hospital, let alone in a wilderness setting. Um, first of all, to dispel some myths about ophthalmology. The common misperception is that we sit in dark rooms all day like bats looking into people's eyes with huge waiting rooms of grumpy patient's sat outside. Uh No, it's much more fun than that. Far more interesting. We see a lot of trauma. It's a nasty gouge which hopefully has now been basically outlawed from the game. Fingers crossed, less work for me. Um, and this, for example, young lad who was shot in the eye by a friend so called friend with an air gun last summer. You can see the puncture wound in his cornea and CT scan shows he's a very lucky lad. The palate has gone right through his eye and lodged just at the back of the orbit just before it goes into the brain. And at surgery, you can see the eye is completely deflated because it's a through and through injury, we had to remove the eye and of course, then the pellet to avoid this causing uh, issues such as meningitis later. And there is some pellet. Most of the time we spend taking cataracts out, it's our mainstay bread and butter surgery, which is a great operation. It's uh exacting high volume, quick surgery. Patient's at 99% of the time. Absolutely delighted and bring you lots of chocolates and wine. It's just marvelous. I do uh oculoplastic and orbital surgery as well, which means they removed tumor's. This is a big BCC that removed. And then we have to think about ways of reconstructing eyelids and eye sockets, which is also great fun. I also, um, the man that takes out eyes in cardiff. So if you've got a bad I, that's blind and painful and looks unsightly. I remove it. Ophthalmology, travels well to take me out to Kenya, Uganda and all over the world. In fact, um, this is operating at 10 and in Kenya. Um, and I've been um to all the big mountains in the world under the pretense of doing research, high altitude. And he is collecting data at the North pole of Everest. So, back down to reality, back to earth with a bump, I'm going to teach you about some basic wilderness opthamology and I'll see you in good stead both in the wilderness setting and also back in A and E the wilderness of A and E or in a G B practice or wherever you happen to work. So I'm going to tell you about the diagnosis of common conditions, warning signs to look out for serious problems and how to treat. And most important in this setting when and if to evacuate, in terms of further reading, the Oxford Hamburger Wilderness spreads. And it's fantastic for um all these sorts of things and we did a U I A consensus which we updated last year. So that's pretty up to date these papers. And if you want a general book on ophthalmology, if you're interested pen cause book the ABC of eyes is fantastic. So that's potentially further reading for either. Um So first of all, taking an expedition I history history is always most important before you take a group into the wilderness. Stephanie, you want to be well prepared and pre armed. So these are just a few questions I suggest you have in a pre expedition questionnaire. In terms of medical history, has person had any previous eye problems. Is there a family history of any eye problems? Um Have they have had any eye surgery and make sure you specify laser eye treatment because that's not perceived as an operation. So ask them specifically if they've had a laser eye surgery, whether they wear contact lenses will come back to that. And diabetes, obviously, because of the significance of diabetic retinopathy, just a little quick anatomy reminder, I'm sure you all know this anyway. But the eye has a tough outer leathery co called the sclera, the white bit and that goes transparent and the front of the eye turns into the cornea and then you have the anterior chamber in front of the lens and iris, uh you have a crease, the fluid. Uh and then behind the lens, you have the vitreous humor which is more jelly like and stringy and then the back of the eye, you've got the retina, um the optic nerve head opt so called optic disc. And then the seeing end is the macular and the fovea right in the middle of that. Uh the very front is a skin which mucus with music, lots of goblet cells in the conjunctiva is just a norm like normal skin. But with goblet cells in which means it's nice and moist snow blindness, something you come across often, especially in glacial environments. This is one of our porters and one of our medical expeditions, we've given all these guys sunglasses as part of looking after them, their welfare. Um But this chat was using his sunglasses to keep his hair out of the way. So he had a day walking on closure without any eye protection. And you can see the redness of his conjunctiva there and that little green bit in the middle of his, uh, cornea which actually stained up with flores in which shows he's essentially a corneal abrasion where, where the ultraviolet light has burned through the corneal epithelium. Very, very sore, extremely painful snow blindness. Um, and I would liken it to being stung in the eye by a wasp. Um, it's so sore. So, um, these people, if you've ever had snow blindness, you know what I mean? If you haven't just be sympathetic to people who have snow blindness, it's very painful. So you have painful gritty eyes and very averse to the light, the conjunctiva will be red. If you've got flores in and put some in, you will see the stain and causes are ultraviolet light. UVB, especially reflection. So if you're in a glacial setting or altitude where the air is rarified, um, then you will certainly be more likely to get snow blindness. So in terms of treatment, it's not a great deal you can do but rest light avoidance. So that porter I showed you earlier, he just crawled into a sleeping bag, but the hat over his head and by the morning he was better. Some antibiotic appointments and chloramphenicol ointment will help just to lubricate the eye more than anything else and prevent infection. Don't forget oral analgesia for any eye problems, eye conditions are painful. Um, so please do give analgesia or I M I B whatever you've got if necessary for more serious i conditions, um, sometimes nonsteroidal anti inflammatory drops may help, but I'm not a big fan. There's no real need and then obviously prevention is better than treatment and cure. So, sunglasses and goggles are the way forward to prevent um, snow blindness and these need to be good quality UV, protective sunglasses. So not sunglasses, such as those on the left, designer sunglasses have no place on the mountain. You want decent mountain goggles like the labral is gone or at least decent wraparound shades, high quality. You could do your Remy a trip with a piece of bark with a slit in it. So if you, if you really are in a survival situation and do not have sunglasses, please do feel free to make some ridiculous sunglasses out of bark or wood or paper or whatever you've got just to avoid getting snow blindness, conjective itis, probably the most common thing you'll see on an expedition setting or indeed in A and E G P practice. Um and symptoms are red, painful eyes, vision is preserved usually. So vision's good. You got red, painful ized either with pus. Uh this is a nasty gonococcal conjunctive itis with lots and lots of pus. So that is a bacterial conjunctivitis, the pus, bacterial antibiotics, um grittiness and profuse watering without puss, um suggestive of viral conjunctivitis. Now, the problem here is the viral conjunctivitis is very contagious. So, in an expedition setting, if you don't have very strict hygiene, someone gets viral conjunctivitis before you know, everyone's got viral conjunctivitis. So just be aware of that. And then if it's itch is the main problem of foreign body sensation, it may be allergic conjunctivitis and with allergic conjunctivitis, we commonly see these cobblestone for Pillay underneath the islands. If you flip the eyelid over, you can see these cobblestones and the itch comes from histamine being released from the mast cells when you rub your eyes. So obviously, the treatment should be tailored to the diagnosis or antibiotic for uh bacterial conjunctivitis. Uh not much treatment for viral conjunctivitis. You can give some antibiotic ointment just to lubricate the eye, but it's not really going to help. Um sodium chroma click it, it's a mass cell stabilizer. So that's quite useful. Um and strict hygiene measures obviously for the viral conjunctivitis and indeed bacterial. Just one thing to be aware of. If you've got a non resolving conjunctive itis not getting better or indeed getting worse. If the vision is getting worse, then you got to think that the cornea might be involved with a keratitis. Um They might have a viral keratitis like herpes simplex keratitis or indeed they might have a bacterial keratitis to that answer. And then you've got to be a bit more worried, a bit more concerned if you don't think you can cope with that. I would suggest moving them out and evacuating COVID 19 can't have a lecture these days without a bit of COVID. I'll only mention it once. But just to say that one in 30 people have conjunctivitis with COVID 19 and the eye is a major route of spread. So if you see someone conjunctivitis and respiratory symptoms, please do think COVID, I'm sure you will anyway. But just in case contact lenses, I'm sure many of you wear contact lenses. I wear contact lenses. There are different sorts. Most people these days where soft contact lenses and there are rigid gas permeable lenses. Some people wear that are smaller and harder and these all need to be cleaned every night. The soft lenses you can get daily disposable lenses, which I would suggest to the best idea for an expedition or wilderness setting. You all have potential problems. There is an increased risk of infection if you're wearing contact lenses. Um, and an increased risk of dry eyes. Um, part of the issue with contact lenses and expedition settings, often people wearing them longer than they usually do. It's like changing their normal habits. Um So always take a lot of spare contact lenses. You're not going to put in lenses that aren't comfortable, try and limit the time you're in lenses during the day. So maybe wear them during the day, but not the evening or vice versa. Um, remember glasses, well, numerous times I've been on, on trips where people have just got lenses and no glasses with them at all, which means they're stuck wearing lenses from dawn till dusk, which if there's an issue or if their eyes are getting tired or dry is no good at all. So make sure people have glasses. And this is where knowing from your pre expedition history, you can advise people who are contact lens wearers not to overdo it not to change their habits too much. Um, council contact lens wearers in strict hygiene to washing their hands before they put them in. Um, and as I say, I think daily disposables are the best option on any major trip because if, if one lenses a little bit uncomfortable, you can just whip it out. Um, and start again with a new one and there's no need to be having to clean them, mess around with them and potentially them getting contaminated with nasty bugs. I think the contact lenses, you have to take any potential infection very seriously. So if you have someone with a red eye and any discharge or blurred vision, um I think you have to take that quite seriously. Stop all contact lens where treat the topical antibiotics every hour and if no improvement, they should be evacuated, there's a few really nasty contact lens related bugs that can cause blindness. And I think if you're not properly get it out to treat that he should be evacuating the patient. So things like acanthamoeba and so on. Otherwise you'll end up with a really nasty ulcer like this. This is a significant bacterial keratitis and also right in the center of vision that is going to scar and relieve permanently reduced vision without a corneal transplant. And you can also see that level of pass um in the, in the there we are there is anterior chamber which I hope you'll note is a hypo P in. But that's it. There's also suggestive of a significant infection going right through into the eye. And it's the anterior chamber. If you don't do anything about that, don't treat it. You end up with the eye perforating. So the cornea breaks down, that's the lens sticking out of an eye of an elderly lady who's just ignored the fact her eyes infected for several weeks until she presents with just a foreign body sensation in the eye. And the foreign body was the lens poking out of her eye. So sadly that I was lost, but this is all avoidable. And there's a beautiful view of the north face Everest. This is to remind need to tell you about colleague of mine who on every summit day, he was a contact lens wearer. Um He'd got a bit behind with his contact lens hygiene and so on. And he just had had been uh using the same pair of contact lenses for four or five days on the, on the summit bid and he just been taking them out each evening, spitting on them, put it back in and just not, not looking after his eyes properly. And then on summit day, he went up and for the last few hours, he decided to swap from his goggles, um to a pair of Oakley's. Um, and he had oxygen mask on as well. It's a lot of air blowing against his eyes. So this was mainly for the pictures on the summit, which he got great pictures. But unfortunately, he couldn't see anything because his contact lenses had frozen to his eyes, which it's not ideal. Um, and he could see anything. So he had to be led down from the summit of Everest by two Sherpas. Um, you're lucky to get away with his life to be fair. Um, so a solitary tail always wear goggles and it's not all about posing for pictures and interestingly, um, found in one of the learned journals that I read another chap climbed Everest and his eyes for his knee was doing exactly the same thing, wearing sunglasses instead of goggles. And that was him on the way down with his eyes having to be bandaged when he got down. So dry eyes, um, sound very innocuous, but they can be really debilitating in certain certain situations, but certainly exacerbated by the dry windy, bright conditions that we get at high altitude and if left untreated can lead to infection, um, symptoms and signs again, red, painful gritty, I sometimes enough to cause a headache um and can, can cause blurred vision occasionally. So artificial tears were good idea, goggles, wraparound sunglasses will prevent wind, especially causing further tear of operation. Um And also try and minimize contact lens where if your eyes are getting very dry because that can eventually cause infection. We know that can do now. So just moving on there, it's a loss of vision. So I often get calls from people on expeditions saying in people, expedition medics panicking a little bit because one of their clients has lost vision, either altitude or in the jungle or wherever. And I just usually get in just to calm down and just think through it sensibly. Um And very often things settle and pass by. But usually you can, you can use a basic algorithm to try and work out whether or not you need to evacuate the patient. Essentially. Um I think pain is an important differentiator. So either they got less loss of vision with pain or without pain. Um If it's painful, it's like to be something on the surface of the eye. Um The such a snow blindness or something in the eye or back to your keratitis could be acute angle closure, glaucoma which point they would often have a thumping headache in being sick as well. And quite a hazy looking cornea optic neuritis. This is an odd one and we have seen a couple of times. The wilderness setting, a demyelination of the optic nerve causes pain and decreased vision, but it's a deep headachy type pain. Uh a new, the ITIS as well is painful. So most of those things, the first couple of things you could treat. The other thing is you probably can't acute angle closure, glaucoma, bit Diamox will help. You'll have some Diamox if you're altitude. But those sort of things you need to be getting the patient out for anyway, paying less loss of vision. These are the things like retinal detachment, a vascular occlusion, which we do see occasionally altitude. Um cerebral ischemia, which is often transient loss of vision, briefly, very high altitude and then high altitude, cerebral edema can cause loss of vision, high altitude retinopathy, which we'll talk and get about again surely. Um malignant hypertension which you can, I've seen a couple of times mainly in people who go on trips, expeditions uh and decide not to take their anti hypertensives, uh medication for whatever reason. And then end up with very, very high BP and hemorrhages all over their retina and loss of vision retinol detachment I mentioned briefly because that's probably the most likely thing that you could see. It's quite a common thing we see several a day in cardiff. The risk is greater for short sighted people, trauma increases the risk, especially rotational fast deceleration. So a full punch bungee jumping, that sort of thing, increasing the risk. Um, symptoms are flashing lights, floaters and a curtain coming across your vision and that does require urgent treatment, surgery to fix the retina back on. It doesn't have to be done within an hour, but it really within a day or two that needs to be treated. Otherwise they're going to lose vision and they're not going to get it back so they need to be evacuated. So I think we lost vision, take a full history in terms of pain, symptoms, examine the eyes carefully, whatever you've got, especially measuring vision, um and pupils um if you can't find a cause you're worried, I think you've just got to get the patient out Factive surgery. I mentioned, I think it's quite important. A lot of people now on expeditions will have had some sort of correction to their eyes. The aim with refractive surgery is to change the refractive power of the cornea. So you don't need glasses or contact lens anymore. It's increasingly popular both in the wilderness setting. People who like doing outdoor activities and, and nowadays, especially people in masks and are wearing glasses because you're looking at self on zoom all the time. You don't have to be wearing glasses. And so becoming sharply popular after lockdown, there are different types, some are safer than others, especially high altitude. The older style of practice surgeries to make deep grooves into the cornea with either radial keratotomy on the left there or arcuate keratotomy on the right. Um That's been superseded now by laser surgery where there's different sorts of LASIK is where a corneal flat is created by blade or laser. And then you shave the cornea, um, with, with a laser and then pop the flat back down to either weaken or strengthen the cornea. PRK is when you consider making a flat, you just rub the corneal epithelium off and then shave the cornea with the laser and then just let the feeling grow back under a contact lens that's slower to recover, more painful. Um So less popular but better for thinner corneas and then lay sec is a combination of the two where you need to create a mini flap of the epithelium with a blade or a laser and then you shave the cornea and then pop the epithelial flat back down. So slightly quicker recovery than PRK, not quite as quick as lay sick, but there's there's pros and console and then you can have surgery inside the eye to make to change the power of the lens. As you make a small incision, you either proper lens in the anterior chamber in the front of the iris on the right there, or you take the natural lens out a new lens in uh similar to cataract surgery. But before you got a cataract, um that's permanent. Whereas the anterior chamber lens, the Bakic I O L could be removed later. So those original types of of surgery with cutting grooves into the cornea. They will definitely cause blurred vision at high altitude. What we found is that cornea bulges and so you get really quite blurred vision. Anyone who's had a radial keratotomy will will have this um the other laser type. The LASIK, the Lasix PRK can cause blurred vision. A couple of studies done um which showed that about half of people above 7000 m will get blurred vision. I think it's very important to realize that the risk of infection is great with all types of surgical vision correction. Um And if they've had one of those lenses, but in the eye, if there's trauma, that lens might be exposed, I always advise clients not to change things too much just before an expedition. So don't rush off and have laser surgery a few weeks before you go on an expedition that's doomed to failure. Uh And any infection or decreased vision should be taken seriously. And again, considered to sent evacuation, treat them the same way you treat corneal keratitis. Um And this is why it's important to know from your pre expert expedition questionnaire what they've had. So if they present to you with a problem with their i knowing that they've had laser surgery or lens, but in the right is important. Um I'm sure many of you have read into Thin Air by John Crag. I about the 1996 Everest disaster which was then uh more immortalized into the film Everest. Um One of the players in players in that uh disaster was Beck weathers who was a Texan pathologist. Uh And this is him after they found him, what happened to him was he had had RK one of those that radial keratotomy. And when the storm came in because his vision was so blurred from having had previous corrective surgery, but it had all blurred because he was a higher, high altitude. Um, he couldn't see where he's going. So he got completely lost in the storm, was unable to find the tent was eventually rescued. But unfortunately, you can see from his hand there that's not a glove he's wearing, that's completely frostbitten hand, which he lost, I think most of that hand and his nose, you can see he lost half his nose as well. Um So because he had had a corrective surgery to his eyes is one of those older types of correction. Um, this really had a huge impact on the fact that he couldn't navigate through a storm. So you're moving on to trauma. That's uh, evisceration of an eye with a tent pole. So I removed the chat, removed his own i with a tent peg basically, um, fell, fell over 10, beg took his eye out and not much you can do for that. She had to remove it and give him a glass. One different sorts of trauma require different levels of treatment. Um, there's only one emergency and ophthalmology and that's a little compartment syndrome, retrobulbar, hemorrhage will go back to that in a second. Um, corneal exposure from proptosis, the I sticking out or a little lacerations or penetrating eye injury. Those things need to be dealt with fairly quickly within 24 hours. Um little aspiration is not causing too much exposure, need to be seen soon, but not too quickly. Um And orbital fractures can be left several weeks sometimes before they need to be treated back to orbital compartment syndrome. Um This is the only thing that really should lift the pulse rate of an ophthalmologist. And this is one of the reasons we enjoy our job because we don't have to do much on call. But if you have someone with a retrobulbar hemorrhage, they can lose vision within 90 minutes. So you need to be jumping to attention and running to that patient. Um Usually trauma, usually hemorrhage behind the eye, they get rapid painful proptosis and the eye sticks out. Vision goes, it's very painful. You can check the pupils, you'd often see a deficit there and it requires immediate action to say vision with a lateral canthotomy and canthal isis. So, here's someone with the retrobulbar hemorrhage and compartment syndrome, you see the orbits very tight, lots of fluid came osis under the conjunctiva as well. Patient is in pain. Um So what we need to do is both the lateral canthotomy. So that's the horizontal cut through the lateral canthus and then also the vertical cut. So you just strum the, the tendon there, the lateral canthal tendon and cut that as well. Uh And that will allow the eye to come forward and often you get a gush of blood as well. You should all be able to do this. It's one of those sort of emergency things. You should be able to do that many a any consultants even defer to us to do it. But really, they should be just getting on and doing it and we can buy to inspect their work afterwards is one that's been done in A and E. Um So you can see that the lateral canthus has been completely d hist and cut away and blood coming down there. But pupils come back down nicely having been blowing nice and small, we often see a hyphema from blunt trauma. Hyphema is a level of blood within the eye which you can see in this picture here. It's a sign of significant trauma to the eye, blunt trauma. Usually, um the problem with having a level of blood in the eye like that is it can cause very high intraocular pressure. Um indeed, if the eye is completely full of blood, there will be very high pressure. But in this case, you can still get high pressure as the blood cells block the exit normal exit route for fluid from the eye. And also can be site threatening. There may be other eye injuries if we've had such significant blood trauma, such as a retinal detachment or rupture of this clearer. So it does need urgent treatment investigation. So if you're not equipped to look properly, an eye that's got a significant high female like that, I would consider evacuating corneal abrasion is probably the most common thing that's seen. Um in terms of trauma in the eye setting, it's a mild injury to the eye. Um does need to be treated. The cause is just mild trauma to the eye. So it could be your own hand. When you're taking a contact lens out, it might be your dog, your cat, your friend has just scratched your eye, you might even do it to yourself in your sleep. But what you see is a little bit of the cornea epithelium has been scratched off and with a bit of flourishing in, you can see the area that's missing, it will grow back very quickly. Uh But in the meantime, it's very, very painful. Um So acute onset of red, painful. I after mild trauma, you can confirm the diagnosis with topical anesthetic because that will be of instantly relief. I'm with the fluorescent because you can then see the Cream Globe treatment, bit of antibiotic ointment. Um And that should be it really, I'm not a big fan of putting ipads on unless you actually have to um for pain relief because under an ipad bugs can grow and you're not letting tears do their, their job of providing a natural antiseptic. So I wouldn't put a pad on unless you have to, you have to corneal foreign body can hear. The history is most important. There's usually a history of hammering. Um, usually something metal. So an ice ax or a hammer or indeed, maybe a bit of stone, but a little bit high velocity, a little bit of metal usually has flown into the eye, high velocity and embedded into the cornea. Obviously, you want to make sure it hasn't gone right into the eye, but often you can just see a little bit of metal stuck to the surface of the eye. So again, red, painful gritty, I the foreign body sensation, um topical anesthetic again will help a because the patient will then be prepared to open their eye and because you can then see what's going on. Um And then a bit of flourishing to show up somewhere. The bit of metal is you should be able to remove foreign body with a needle. Um, preferably with some magnification of some sort with lots and lots of topical anesthetic and then lots of antibiotic ointment because sometimes they can get infected. Sometimes we have to remove the rust rings from the central cornea. But again, that should be saved later on, I think in the wilderness setting and don't forget the sub tassel foreign body can get out of the way there. We are sub tassel foreign body. So if you can't find a little bit of metal and there's little striations on the cornea, it might be. There's a bit of metal under the eyelid. So then you have to flick the eyelid over and just check. There isn't a bit of metal under the eyelid, eyelid lacerations. So the lid margin is interrupted. You need to consider stitching yourself primary repair, especially with the upper eyelids because you don't want to have corneal exposure. Um If you're not prepared or can't repair the eyelid, you're gonna have to get them out. So lots of ointment patch, the eye and evacuate the patient. So here's a full thickness lidl aspiration, not causing too much harm. That one you could just had that and get them out, but it might have damaged the tear that so it probably needs further investigation. Um This is an upper eyelid lacerations and you can see even with the eye closed, the corneal is cornea is still exposed. So that needs repaired urgently. And if you can't repair it, lots of ointment had the I get them out. Here's a nasty double eyelid lacerations from a plate glass window that the fellow walked through. You can see significant eyelid damage there. The I miraculously has been uh not touched but you can see really nasty um eyelid injuries which look fairly awful, but actually with a bit of judicious prepare come together nicely and patient had a great result. Can see again straight away. This, the eye has not been so fortunate. There's a large amount of blood within the eye and the eyelid looks very disorganized, but just to show that again, the eyelids come together nicely. Uh If you find all the respective ends and the I wasn't so happy, I don't think blowout fractures are all mentioned so very common, especially in the sporting environment or outside pubs on a Friday night. But also I've seen several in expedition settings as well. The idea of the blowout fracture is that the the eye socket, if it's submitted to significant blunt trauma, such as with a bore baseball like that, rather than the I splitting into that, the floor of the orbit is specifically week designed as being weak and we'll take some of that pressure and that will just bowel and crack and fracture downwards, which means that some of that in sudden increased pressure inside the orbit is relayed south instead of causing the eye to split open. And what you tend to see then is that the the contents of the orbit herniate out into the maxillary sinus. And what you see in terms of symptoms and signs is the patient may well have double vision, the eyes sunk back in words and potentially downwards and they can't look up because the inferior rectus is trapped in that herniated tissue. Um in terms of treating blowout fractures and they can be, as I said earlier, they can wait and they can, until they get home. If they've got double vision, they're going to have to leave at that point penetrating eye injuries. So here's an injury to the eye penetrating or nonpenetrating. Some are very obvious. So this chap's clearly got a screw sticking out of his eye, that's very much penetrating injury. Um Again, here, this, this person's got a bit of metal sticking out of their eyes and that is most definitely a penetrating injury. Um And yeah, this nail that very much that is definitely a penetrating injury of a nail into the eye, but not all those obvious is that this is also a penetrating injury. It's a full thickness corneal aspiration, but not nearly so obvious. So how can we tell whether an injuries penetrating or nonpenetrating? Because obviously, if it's penetrating, it's a much more serious proposition and they're going to need surgery, antibiotics. Um And there's certainly visual vision threatening. So if visions down, that's a worry, the mechanism of injury is important, especially as high velocity um with a sharp instrument or glass or metal, um that piqued pupil that we saw with other injuries important. This is another penetrating injury that, that sealed itself. So what happens is when you have a penetrating injury, the iris, the colored part of the eye comes up to that injury and just blocks uh the wound and that's to try and um uh put it, put a stop to fluid, leaving the eye and stop uh bugs getting into the eye. So it's a natural way of blocking the wound. But what it means to you looking at the eyes that you have peaked pupil, and then obviously expulsion of ocular contents. If you can see bits of the eye hanging outside of the eye, such as here, the iris has come right out, that's obviously a penetrating injury. And then if the patient has a soft watery eye, so you can just gently palpate the locked the eyes. And if one is very soft compared to the other one, um then you might well have a penetrating injury on your hands. Obviously don't push too hard on the eye management if you've got a penetrating injury and that patient needs to be evacuated immediately for specialist treatment. So start them on antibiotics, gives them some analgesia, pad the eye and get them out and then they'll need treatment such as this um where you stitch the cornea back together and hopefully get them back to a normal. I let's have a look at the eye at high altitude. Now, it's actually very rare to have any symptomatic changes um to the eye at altitude, dry eyes, have you said common but preventable, there's a slight rise in intraocular pressure altitude, which again is physiological of no pathological consequence. And the same with the subtle increase in corneal thickness that we see altitude you get occasional transient visual loss due to cerebral hypoxia. But what is commonly retinal changes not be symptomatic, but they are common heil to direct neuropathy. We see hemorrhages, we see cotton wool spots which are just hypoxic infarcts of the nerve fiber layer. And we see optic disc swelling, not papilledema is such optic disc swelling just because the blood vessels are engorged. And as I say, these are normally asymptomatic. But if one of those hemorrhages occurs, the macula central vision, then you're going to have decreased vision. So what's important to understand is that retinal vascular tortuosity and good and engorgement is normal physiological retinal response to hypoxia because the retina is very demanding of oxygen and therefore needs lots of oxygen coming in from the blood and therefore engorgement of blood vessels. So for example, here on the left is the same retina at sea level and on the right at 5200 m every space camp just after arrival, you can see how much thicker and engorged those blood vessels are. As the as the body desperately tries to get enough oxygen to the retina, that's a normal response to altitude. What's not normal is then having lots of hemorrhages after. So this is after climbing between 65 and 72, 513,200 m and then just highly exertionally bay, lots of little hemorrhages popped out all over the place, but completely asymptomatic because the macula is not involved. And the studies that we've done seem to show no relationship to raise dramatically. It, so some people thought it was because of sticky blood, um thickened blood. That's not that there doesn't seem to be a relationship to AMS symptoms or higher truth, cerebral edema, pollen edema, but it does seem to be as exertion. So the rate of a sense if you're going up very quickly, the maximum mouth you detain to the higher you go and how, how exertionally that is. If you drive up, you're not going to get images. But if you run up, you are, all these things seem to be involved, but there's still lots of work to be done. They're working out exactly what happens and of course, what's happening in the retina may well be happening in the brain as well. So in summary, don't be scared of eye problems. Most expedition eye problems related to contact lens abuse or use um and conjunct devices and say almost all eye problems are preventable. And as I say, the only I emergency was all orbital compartment syndrome, retrocaval hemorrhage. But if you excited about being an ophthalmologist now or you just have other questions, please don't hesitate to email me. Thank you for listening. Hope you enjoyed it. Take care now. Yeah.