Thank you, Bruce. I've certainly been picked up in a big way. I hope I can, live up to this.

Good evening, everybody, and, welcome to, a talk on pre-purchase eye examination. And it's, it's fairly dry as most pre-purchase examinations are just simply a very thorough clinical examination. But I thought I'd throw in a little bit about ocular ultrasound, which is something that, many of us don't do, but it can help us, to evaluate, some of the things that we're seeing in eyes and, also some of the tricky eyes that you see outside of pre-purchase examination as well.

As we go through tonight, I'll show you some examples of things that I, I've seen throughout the, the last year, and give you some tips on how to get more information on these problems if you need them. So, really, the, the pre-purchase examination, you gotta think about why you're there. What are you doing?

Now, you're there to act on behalf of the purchaser to help them make a decision. So your main job is to identify any observable o ocular abnormalities. And then you're supposed to give a judgement on the potential importance of these abnormalities with respect to the intended use of the purchaser.

And sometimes this judgement can be really difficult, and it's something that takes years and years of, of experience to say, well, yeah, that one was important. That one wasn't important. Sometimes that experience comes with a, a bit of a sour taste if you happen to get the judgement wrong.

But we're only human, and we all do make mistakes. One of the things that I find very useful, and I encourage my younger vets in the practise to do, is to ask somebody else. A pre-purchase examination is not about making a split second decision.

There is time to think about it, so do use that time. Anytime I see, an eye that has impaired vision, and we'll talk about how badly damaged a horse's eye has to be to impair the vision later. But if I see that it's got impaired vision, or I think that the eye is painful, then it's always important and immediately I reject that horse because there is something radically wrong there.

In a pre-purchase examination, you're generally looking for subtle lesions in a normal eye. Sometimes they're not so subtle, but generally they are quite subtle. And as with any pre-purchase examination.

You have to have a routine and you have to stick to it. Make sure you're not missing things, cutting corners. And one of the most important things is to remember that the temperament is important.

An uncooperative animal is impossible to evaluate with respect to the eye. Now, I take that in with the rest of the pre-purchase examination and say if the horse is that uncooperative, then really, is it a good buy for the purchaser. And the answer is generally no.

So, ophthalmological abnormalities that we're looking for generally fall into three categories. And the first category is the safest, and that's the ones that don't affect vision and are not progressive. So they're little abnormalities like collibomas, iris cysts, Y-shaped suture lines in the in the lens.

Those we know are very safe, and they're suitable for purchase, but they still need to be noted down as part of your examination because somebody comes along 3 months later and sees that. Then the purchaser is going to be asking questions. The second group is the progressive or recurrent problems.

Now, they're not affecting vision at the moment, but they may do with time, and particularly, this includes things like early cataracts, small cataracts, equine recurrent uveitis, particularly in the early stages, maybe small squamous cell carcinomas or glaucoma. Now, are they going to affect vision? Well, they may well do, particularly if they're left untreated.

And then the third group is the ones that are affecting vision now. So, cloudiness of the cornea, severe cataracts. Now some of those can be treated, and if they can be treated, then it may be that the horse will be suitable for purchase in the future.

But I always recommend that the eye be treated prior to purchase. I don't recommend people buy a problem I and then say, OK, well, we'll treat that, because the, the chance that you're going to get it 100% right is not 100%. So, you, you don't want to be buying trouble for people.

So the pre-purchase exam itself has two distinct stages. We've got the daylight phase and we've got a darkness phase. So we start off in the daylight, and we're looking at the horse's ability to navigate obstacles.

Does it trip over buckets? Does it trip over steps? Does it walk into doors?

And believe me, every now and again you do come across a horse that they don't realise is blind. They just think that it's a little bit skittish. Globe size is another one, so compare one side or one eye to the other.

So you're looking for things like microcornea, endophthalmia, exophthalmia, things like that. And the angle of the eyelashes and ocular discharge. Certainly, if it's got a very gunky eye and or you've got downward pointing upper eyelashes, then that's painful eye.

The eyes being drawn back into the socket, the eye is closing a little, and if it's not equal, With the other side. That's a painful eye. And again, that raise, rings alarm bells for me and raises all sorts of questions.

And I would be as likely to fail that just based on that, but generally I ask a lot of questions first. You want to see, to be giving them the benefit of the doubt. And then you've got the darkness phase.

And here, again, you're looking at the ability to navigate, but this time in dim light, the horses have extremely good night vision. And so if they start to knock into things or become anxious when the lights go out, there's a problem. Night blindness is one of the things that we see, particularly in association with recurrent uveitis.

In the dark, you'll also be looking for your pupillary light response and dazzle responses and seeing whether or not they're appropriate for what you're doing. And the rest of the thalmic examination, and you're looking at, the horse in the dark because that increases the pupil size without having to use midtriacates aces. And also, you're looking to reduce reflections from external light sources.

So when we're looking at the schematic of the eye, it's really most of the eye is just for conducting light from the external part of the world through the cornea, anterior chamber, lens, and vitreous. And that's just to bring the light through in a focused way so that it focuses on the retina at the back. So, most of the eye should be very clear, and is the light path, and then you've got the light sensing portion, which is the very last bit in the fundus.

And so we see, a lot of difference there. Now, what we want to see in a, a nice eye is clear, regular structures, and it should be tidy. We don't want cloudiness, we don't want haziness, torn edges, or precipitates in any of the fluids.

All of those things tell us that things aren't healthy and that there's probably a chance that we're going to have future problems. So the ophthalmic examination itself, and it's not when you're looking at a pre-purchase examination, a specialist consultation. So you don't have to be an ophthalmic genius.

All you have to do is do a reasonable examination. Using reasonable tools that you'd be expected to have in your car. So, a dark room or stable is essential, you can't do this out in the field.

You need a very bright light, you need an ophthalmoscope. It. You may also want some of the other things here, magnifying glasses, a a midriatic, a camera phone, an ultrasound.

We'll see how those sorts of things fit in as we go on. So, your bright light, OK, Papillary light response and dazzle response. Now, by bright light, I'm talking about a light that hurts when you look into it.

You really, really want it to be bright, 75 lumens or or more. And so, and they don't have to be expensive. The one that I use is 15 pound head torch, but very, very bright light.

And You want to be looking for the, the dazzle, smoothness of the corneal surface, clarity of the cornea, clarity of the anterior chamber, and the appearance of the iris. And if you've got tired old eyes like I have, then I always enhance my examination by magnification, because it does allow you to see subtle lesions, particularly when you're trying to get up close to the horse. The ophthalmoscope, usually the examination is just direct ophthalmoscopy.

We're not doing indirect evaluation of the fundus. We're looking to use this to evaluate the fundus and the lens, and because we've already looked at the anterior chambers. Slit lamp, many of your ophthalmoscopes will be set with a slit lamp that slit lamp philtre.

It's to be used for corneal clarity and aqueous flare, looking for very subtle signs of uveitis. In general, the slit lamps on normal ophthalmoscopes are too wide for a very good detailed examination. So it's not really worth the effort, and you won't get very much added information from doing it.

So I tend to leave that out of a normal vetting. With ultrasound, this can be very useful. Again, it's not for the routine vetting.

But it's to give you the added value or added information that you're looking for when you're trying to evaluate an abnormality and say, right, is that really significant, how extensive is the problem? And it can give you information about and particularly objective information about the size of the globe. So do you really have a microcornea or micro mycophthalmia?

The deformation of the cornea, as you press with the ultrasound can be seen, and that might give you an idea of intraocular pressures, whether or not they're low or whether or not they're high in glaucoma. It give you details of masses that you've seen within the globe, and it can give you an idea of the clarity of the lens. So those are the things that I, I use it for.

It's especially useful for cases where the pupil is closed, or there's blood or something else clouding the anterior chamber and cornea. And it's particularly useful, then as a diagnostic. It So this is what we're we're looking at with ultrasound.

It's through the upper eyelid, so it's just a little bit of gel on the probe applied directly to the upper eyelid, then we can see the cornea here. Anterior chamber, this is the iris with the granular ridica. We've got lens through here.

We see the anterior surface and the posterior surface of the lens, but nothing on the inside, generally. And then we've got the vitreous, which is again very, very clear going down onto the choroid at the back. In this older horse, we can see a little bit more detail of the optic disc and the optic nerve coming down through the back of the eye here.

And you see a little bit less pressure in the cornea. So we're getting a wrinkling of the inner surface of the cornea. It's, so that pressure is a little bit lower.

It's not terribly low, but it is lower. And the thing that is obvious here is that we have this opacity in the lens, and this is consistent with the onion ring type, nuclear sclerosis that you get in older horses. So it's just an old age change, both of which are acceptable.

So the things that we're going to evaluate in this examination, we'll go through the whole list going from. Outside the eye to inside the eye, and going from the front of the eye to the back of the eye. And we've got to look at every component of this examination.

So with the fairly light response, remember to look for direct and consensual. OK, it is important, it can be sometimes overlooked in the heat of the moment, but it is useful to, to note the proper propillary light response, and it would help if I spelled it correctly as well. I just noticed that.

And I can think of one example where it was quite crucial for a horse. I I had a horse, about 10 years ago. At Liverpool, and it was suffering from iris paralysis, and it was sent to us because it was considered by the owner to be blind.

But the horse was definitely not blind, but it had become spooky, but instead of being spooky in dark light, it was actually spooky in bright daylight. And the reason it had become spooky was that one of its irises had become paralysed. And so it stayed with a dilated pupil constantly.

And what we found in that horse was it was very easily dazzled. But it had no papillary light response, and certainly no direct. It did have a consensual though, so the retina was working, the eye was working.

It was just the iris that wasn't. And in the end, what fixed that horse was tinted contact lenses. And a tinted contact lens in that eye helped it to deal with the bright light of sunlight, and it behaved normally after that.

So, again, it needs to, you need to think about what might be going on there. And occasionally look for the zebra, you look for the unusual sign. A dazzle is a very good assessment of retinal function.

It's not stopped by corneal lens opacities, a a good bright light will shine straight through that, even people with very dense cataracts can see light and dark. So you don't have to have visual acuity for the dazzle response. And so it's useful for that and it's more reliable than a menace response.

As I said before, we all do the menace response but it's not necessarily the test we think it is. Yes. When you do a menace response, it just means that the horse has minimal vision.

And in fact, you can menace a legally blind person. It's not very nice to do, but you can menace an eye that is legally blind. So it doesn't mean that the horse can see very much just because it can see your hand move.

And conversely, a negative menace in horses may just mean that the horse doesn't really care, and some very laid back horses won't. So, unfortunately, the, the idea that we can measure visual acuity in horses is very, very much a dream. It would be lovely if we could, but we can't, really, all we can say is, yes, the eye is functioning.

No, the eye's not. We can't say if it's functioning 50%, 60%, 70%. There's no way of doing that.

So, again, it gives a limitation to how much information you can give somebody when we start saying, well, we think that the vision might be impaired. Well that's really just a guess, cause you can't actually tell just how impaired the vision might be, unless it's really impaired, in which case if it's really impaired, then it's probably not a good purchase. Pigmentation, again, looking for, areas of white around the eyes.

And we've got these sort of albino type eyes, solar dermatosis around the unpigmented eyelids and sclera is really a problem, as is the development of squamous cell carcinoma in these animals, particularly in geldings. And so, always something that I note, the colour of the 3rd eyelid, the colour of the upper and lower eyelids, and I warn potential purchases that that is something that might develop. It doesn't mean it will, but they, you don't want them to go away thinking that you've missed saying that, particularly when somebody else points it out to them a couple of days later.

Sarcoids, again, periocular sarcoids, I wouldn't recommend people purchase a horse with a periocular sarcoid. They can become quite aggressive. They can grow rapidly, and they can affect the vision, particularly in the upper eyelid, they can affect the function of the upper eyelid.

So, it's not to say that every horse with a periocular sarcoid will go on to go blind. It just means it's not a recommended purchase. What I would recommend is that they have it treated first, and then think about purchasing the animal once that's been done.

You wouldn't recommend that somebody buy a horse that was lame and had multiple stifled chips. What you do is you recommend that the chips get removed and then they look at at purchasing the horse afterwards. It's the same pro, principle.

So here we can see a horse that has had a periocular sarcoid treated below the lower eyelid, and the white hairs are the remnants of that treatment, and it's been very successful. And that horse was then bought. Melanomas again, definitely not a good buy, and the reason that they're even worse is because they're very difficult to treat.

And often unsuccessful at treatment. And this had had previous treatment and still present and growing rapidly. So not a good purchase.

Unfortunately, in this case, the, the purchaser brought it to me 3 days after they had purchased it. And not much you can do then except say, oh, bad move. Microcornea.

In our part of the world down here, we see a lot of this because it's fairly common in cobs and cobb crosses, whether or not that's because they felt that a wild eye was a, a, a desirable trait. I don't know. But a microcornea is a minimal blemish, versus a microphthalmia.

Which is often associated with big problems. Oftentimes they have lens changes and they have problems with the, the lenses luxating. So, mycophthalmia, big problem with a little eye.

Microcornea is not a problem. It's just the cornea is a little bit smaller. And as long as it's not insanely small, then I would not say that the horse is unsuitable for purchase.

I would just note that it was present. Great, and this brings us on to some eyelids. And again, look at the eyelid margins very carefully when you're examining a horse, and look at the 3rd eyelid.

In this case, this was a 6 month old foal that had been homebred and then insured. And then these hairs that you can see around the medial curuncle of the eye had developed. And it was then examined and, oh, some problems here.

And so they wanted to know what was going on. And basically, what we had was chronical dysraxia. We had dysplasia of the lower eyelid.

We had dysplasia of the 3rd eyelid, and we had dermoids of both the medial curuncle and of the ventral corneal limbus, . And so, lots of problems. Now, obviously, the insurance company then, well, this horse can't be insured because of problems.

So it's, it was difficult because the owner had insured this horse in good faith. They want to know that all of these problems were there. You couldn't see them from 10 ft away.

And particularly as you see this horse. 3 months after I first examined it, so it was a 9 month old foal, and re-examined it, and we were looking to, to trace it to get rid of some of those hairs, and they've actually fallen out by themselves. And at this stage, a year later, this fall, or yelling now is actually doing quite well.

It does have a lot of changes with the eye. You can see here, the dermoid at the bottom of, of this eye, which is being left alone. It's a, a minor benign blemish now.

We've got the caruncles here. We've got the third eyelid, and which is split. And we've got an abnormal shape to the, the lower eyelid, but none of those things are affecting its vision and it's not causing it any ongoing problems.

So again, judgement is, leave it alone. But at first sight at 6 months of age, I was a bit nervous as to how this was all gonna turn out for this little fault. So sometimes you do need a little bit of time.

And again, it's not improper to say to somebody, whether it be an eye or a heart, a prep examination, I've found an abnormality. We need to see what happens over a little bit of time. Not everybody's got time to spare, but it is worth at least asking for it.

This eye, very interesting one, prognosis in this is quite severe edoema there, obviously affecting the vision. Couldn't see through that in a month of Sundays. It does seem to be associated more with the upper eyelid function than it is with the lower eyelid.

However, I must admit, no idea. Exactly what triggered this and what caused it. The only thing I can say is that it resolved.

Whether that was his response to treatment or just time, hard to say. But you always try and take any, value in a win. And, it went on to have completely normal function afterwards.

So sometimes it's hard to guess what the prognosis is going to be. And when you're put on the spot by a purchaser, sometimes you just have to say, I don't know. Better to say you don't know than guess wrong.

But it's, it's hard when they're, they're really pressuring you for an answer. In this case, we've got a lot of corneal scarring, a very good picture of it and. Pigmentation of the ventral area of the cornea as well.

And again, this scar was from a melting ulcer. So that's a pretty good outcome from what was a hideous eye to begin with. In time, that continued to scar down and contract, and the horse was visual to the point of jumping afterwards.

So again, it may not always be cut and dry as to what's Going to do well and what's not going to do well. And so we need to, to give some thought to it. But would you purchase these things at the time?

And that's part of what the the purchaser is asking you to do, and the answer would be no. Let's see if they resolve, let's treat them, see if they resolve, if they go in the right direction, then they might be a good purchase. If people are in a hurry, then you'd have to advise them, steer clear of this one.

And the keratopathies certainly fall under this category. There are a number of different keratopathies that are recognised in horses, all of them leading to some degree of corneal opacity. And whether or not it's superficial, deep, or endothelial, you'll see some degree of corneal edoema.

So, in general, if you see sort of a superficial keratiis, little pock lesions in the very superficial epithelium of the cornea. The horses might have slight discomfort, rough surface. There's no vascularization.

They are responsive to time and or steroids. Again, looks better for you if you've done something rather than just and like say, yeah, they'll get better. And they often don't recur.

And very rarely do they recur. And so in a case like this. Again, I wouldn't be saying, yes, rush out and buy it now.

What I'd say is it's likely to resolve over the next few weeks, maybe a month, and at that stage, it would be suitable for purchase after re-examination. If it does resolve, then fine, you can be quite happy to say it's not likely to recur. OK.

With some of the deeper keratiti, you'll see vessels developing, you get fibrosis within the eye, a lot of reactivity, you get some edoema. Again, they can resolve quite well, but sometimes, and oftentimes you'll see varying degrees of scar formation in the, cornea. And in those cases, they may recur.

In which case, it's a problem that you're going to see again. So if it's very superficial, I say, OK, if it's deep and you've got these big sort of vessels that you can see here, it's, I'm worried that that is going to be a recurring problem with time. And so I warn people, the best steer clear, unless they really, really want the horse, in which case they buy it with the caveat, they buy it with your warning.

Same thing with endothelitis, OK, it's not a painful condition, so sometimes these horses look quite normal until you get up close to them and have a look at the cornea. And you see these areas of edoema. OK, so you might see deep blood vessels through here as well.

Again, they can be treated, they do generally resolve, but not always, and not always quickly. So again, if people want to buy this horse, I would recommend that they don't buy it until it has been resolved. And I can think of a number of occasions where colleagues of mine and even myself, although I got away with it, have recommended to, to buy horses saying, yeah, no, we can fix that, and, we'll treat it for free.

And I can think of one classic case of a racehorse that, mild clouding. They thought it would be fine. But then it started to get worse, started to show signs of uveitis and increasing pain.

And what seemed to be just a little bit of superficial keratiti was actually quite a severe case of recurrent uveitis. And then we started to get lens changes, started to get the cataract. It got very expensive.

And again, if you've given somebody the assurance that it's not going to be a problem, They're going to come gunning for you. So do be careful about saying, oh yeah, that that'll clear up, . Make sure it has cleared up before you say, yeah, this is a good purchase.

Cause it is somebody else's money at the end of the day. The anterior chamber of the eye, again, clarity is key here and that's what we want to see. Aqueous flare.

It's, it's the first sign that uveitis is developing, and it's the last sign that uveitis is resolving. So any degree of aqueous flare, so, you get the little particulate protonnaceous matter within the aqueous of the anterior chamber. It causes a diffusion of light, and you sort of see a grain of that, fluid.

Right, that tells you you've got uveitis. Be careful because uveitis is horse is often recurrent and it becomes an accelerating process over time. And again, blood, hyperpyon, they're definitely immediate reasons not to buy a horse.

If if it's got marked pathology, let that settle before you say, yes, OK, well this is going to be a good eye. Cause again, you get adhesions, you get all sorts of problems. So we're talking a little bit about uveitis, and it is probably the most common problem that vets get hung by when it comes to judgments of a disease that's gonna come back and bite you, cause it can come back in so many different ways.

And one of the signs that you can see in a horse that's had recurrent, uveitis is iridial power. And so you can see here these paler areas of Whitening within the iris, where the iris is losing its pigment, and that's just one of the signs that you'll see. In some more advanced cases that haven't gone so well, you may get adhesions of the iris either to the lens or to the cornea, depending on whether or not they're posterior or anterior sneaky.

And again, that is problematic because if you try and dilate that pupil, and in this case, the pupils actually held in this hourglass shape, and you see the pupil there and there. And it can't expand. And you can try and expand that with adrenaline and various other mid-retics.

And, all you end up with is an anterior chamber full of blood. So, you, steer clear of anything with that kind of change. And this is sometimes what happens if you really do try and force these things open.

And this was forced open. It was a posterior sneaky and where the granularridica had So, joined to the lens, and when it was forced to open with adrenaline. We see that the pupil did dilate, but it tore the iris, as we said before, tearing, not a good thing in the eye.

Ended up with terrible high femur, and that was treated, but there was nasty changes and cataracts as a result. So, stay away from from problems like that. Aridial cysts.

OK. Again, looking carefully at eyes. So this is the same eye, just looking at slightly different angles.

So here we see the nice ovoid shape of the iris, so it's formed because horses have panoramic vision through there, so a circular, pupil isn't useful for them. And hidden up here, this is a 24 year old pony that I just happened to look at, and they were actually concerned about the sunburn and solar dermatosis around its eyelids. And I looked at it and I said, Oh, so how long's it had that mass in the iris for?

And they'd never seen it. It was actually in both eyes, and they'd never, never seen them. And they're radio cysts, so congenital.

Been there since birth, but they'd never seen them. But, then I got a phone call back the next day from this client because their friend had told them. That they were actually original melanomas.

Because their horse had died from that. So of course you go back out and say, well, no, it's probably not have all the conversations. And how do you know?

Well, I put the ultrasound on. And with an iridial cyst, I was able to put an ultrasound on, and you see this hollow structure here, that's fluid-filled. If it was a melanoma, it would be solid tissue and look grey like the granular ridica.

So simple, quick, easy test to show that it's an Irish cyst. If it's been there for 24 years and not done any harm, then it's probably not gonna do any harm. So leave it alone.

Here's a, a different case. In this case, this was a previous corneal injury to this horse and it had some pigmentation of the cornea. And on ultrasound, we could see that it was actually the iris.

That had herniated up into the hole in the cornea that had been there at some point, and it's formed a permanent syney with the, the cornea as a result. So the eye was visual. The eye was OK.

It was fairly quiescent, but pretty severe trauma. And so I was very cagey about saying that this was not going to be a problem in the future. And, it did actually have recurrent uveitis that developed about 6 months after that examination.

It probably had uveitis beforehand, but, we kept being assured that it didn't. So, again, severe changes like that, I would expect that that horse has got uveitis and I would be staying away from it. So the lens, OK.

Again, clarity is the key, right? We're still in this whole light path area, so we want as much light to get through as possible. And any opacity is a cataract, and all opacities except the classic Y-shaped suture line are important.

OK, so. You want to see, I haven't got a picture of it, unfortunately, the Y shaped cataract, it's really, really difficult to get good pictures of the lens, it is difficult, but. They're, they're very classic cause they're a very dense, Y shape.

Most people have seen them, and those, you can say, yeah, that's not gonna be a problem, don't worry about that. Then the next thing that people seem to get very concerned about is these onion ring shapes here that you can see sometimes when the pupil's really dilated, and you can see it here as well. And this is just, nucleosclerosis, a senile eye.

It is a form of cataract or change, but it's, when you look at the, stars of Winslow and things like that in the fundus, it is clear. So, not a problem, and I expect to see it in older horses. I don't worry about seeing it.

It doesn't worry me whatsoever. But other cataracts, will they progress? If they're congenital, then probably not.

So if it's a very young horse that's had a cataract from birth, it's probably not going to progress. If they're very dense, they've been dense from the beginning. And unfortunately, dense congenital cataracts, you've got no option but to remove them.

If they're required, well, they are most likely going to continue to develop, and particularly cataracts with any other signs of UVIS. Will progress, OK, cause the cataract is often one of the signs of uveitis. It's one of the events that occurs, an ultrasound can help us with our assessment of of cataracts.

Some of the other signs that we're looking for with cataracts, you see here where the iris is attached itself. To the lens, OK, and that's UVIsis, we've got posterior sneaky and a little bit of tearing of the pigment away from the iris. And that causes anterior capsular change, and you start getting a cataract development.

So the whole thing mashes together. And you get this sort of thing. So, with an ultrasound of this eye.

You can easily see this big cataract in the anterior component, and, yeah, well, it's easily see that that's not going anywhere in a hurry. It's only gonna get worse. In other cases, this was a very subtle.

Cataract that I saw recently at pre-purchase examination. And progression may be hard to predict. Maybe it's gonna change fast.

Maybe it's gonna be slow. It may not change. It probably will, though.

And you can advise, re-evaluate 3 to 6 months and see if you can gauge how fast it's changing. In this case, the moment I mentioned the word cataract to the potential purchaser. They backed out at a million miles an hour.

So I didn't even have to go into a long conversation. They said, I won't buy another horse with a cataract. I had one, and it was a disaster.

So, from that viewpoint, it's, it's a bit like saying the word navicular to, a purchaser. Tends to make them run away. So, cataracts, you often don't get to see how they're going to progress.

Vitriol haze. OK, greenish glow in the back of the eye, it's a bit fuzzy, right, that's vitritis. And sometimes associated with leptospirosis, and again, degeneration of the vitreous is one of those things we do see with uveitis.

And so you get these changes, but not all things in. Or all sort of solid objects in the vitriol mass are abnormal, and when, while the vitreous should be clear in itself, you can sometimes see little membranes that float. In And they're just remnants of the, vitreal membranes, blood vessels, the, hyloid vessels.

And you can't see them generally on routine ophthalmoscopy. And so, You find the examination, you haven't seen it, it looks clear, you just see it on ultrasound. So sometimes the ultrasound's a little bit more sensitive than you really want it to be.

But normal change and you don't need to worry about those. But if you start getting degeneration of the vitreous and particulate matter developing with it, and it sort of looks like a snowstorm, then you've got some problems and it's usually Uveitis. So that brings us to the, the funding examination.

This is the part that really sends the willies up people, right? What are you gonna see there and what do the changes mean? Well, in general, the changes often mean very little.

If you've got a clear light path right the way back to the, fundus, and you've got a horse that dazzles and doesn't trip over, then it's probably OK. So you say, well, the horse is sighted, and there's no abnormalities in the light path, and generally it's all right. You can go mad thinking about all of the abnormal.

Changes that are actually normal in the fundus or the normal abnormalities as they they put . So, what we're looking at is the optic disc and the retina, and you've got the torpedal and non-terpedal regions of the the fundus. And generally, you, you're looking at the optic disc here.

It's pale salmon pink, and you've got the short blood vessels that just go across the edges, and then they radiate out into the retina proper, away from there. And in the, the torpedal area, you've got the stars of Winslow, which I always look for first, and, we'll see why in a moment. But Fundic imaging.

This is an area that's really sort of taking off at the moment over the last couple of years. I think it's great, because this way you can see something, you can think, oh my God, is that, isn't that, you know, what should I do? Take a picture of it.

Send it to somebody that you trust, share the blame. And that's what it's all about, is negligence is doing something that other people wouldn't do. So if you've got a consensus amongst a group of people that you trust as being like rational, then you can't be accused of being negligent.

It is protection, so do call upon your colleagues to do this, sort of thing. So, in this case, I'm just taking a a simple smartphone. I've got a camera app which was free, downloaded, and all that's used for is to keep the lamp on.

So you've got a coaxial light right next to the, the lens of the camera. It keeps it on, just makes it easier for the camera to focus. If you're not using, a static light, it makes, it does make it difficult.

And then you've got a diffuser over the lamp, and you can see my expensive diffuser is a little piece of sports tape. And you just put that over. If you don't do that, you actually get too bright a light and it, it flares so that you can't really see the detail.

So the diffuser does help. And then you put it as close as you can to the horse's eye, generally in the dark, so that the pupil's larger, or if you use ropecamide, you'll get much better pictures. But I, as I say, I don't tend to use ropecamide in my clinical, in my pre-purchase examinations.

But if I really see something that I think is special, then I will use it so I can see it. And then we've got that image there, which is essentially what you see on the screen. Now if I'm looking at the fundus, the first thing I look for in the fundus is the stars of Winslow.

If I can see the stars of Winslow, it means that the cornea, the anterior chamber, the lens, and the vitreous are all clear. Now I've looked at them already, but this confirms it. They're definitely clear cause I can see right the way through the light path is clear.

So now all I need to determine is whether or not the fundus is functioning and whether or not it's broadly normal. And so the stars of Windsor, if you can get them in sharp focus, so there's black dots, you want them in sharp focus, near the ends of the choroid vessels, and once you've got that, you know that your eye is is doing OK. Again, we're using direct imaging, not indirect on this.

So you need to, to look around a bit. And with the camera, you might look at different areas and then you can meld them together if you can be bothered with a bit of time, and you can make a picture of the back of the eye. And I've done that to a couple of these, other ones and just focused in on areas.

So You're looking at the pupillary light response again, it's normal light response and you can dilate the pupil. OK, and we're looking at normal fundus through there. OK, here we've got a change, right, we've instead of just having short vessels, we've got some longer vessels coming into here, got a little bit of power here, and we've got a very strong vessel coming through the retina there.

Still normal. It's just a variant OK. This is another normal eye.

We've got some pallor through here. So we've got retinal depigmentation here. We've got some real pale areas in the optic nerve, and again there.

And then we've got some hyperpigmentation just on the edge there. And again, these are all changes that occur in the retina in response to all sorts of things, mostly inflammation, but they're not affecting vision. Not so that we could notice in these horses.

So, again, the sort of normal abnormalities. So don't get too hung up if the fundus is working. OK, and again here we've got some halo effect around.

We've even got loss. Of the blood vessels here. OK, and you can see them through here and pale like sort of areas of the pigmentation.

OK, again, still a normal eye, so normal variants. When we look here, this was an interesting case. This horse did not have a normal light response.

It was one of these horses, I took it into a dark stable, it got agitated. Then I looked at the pupil, and it was big in the dark, but I shone a light on it and it stayed big. It has a hungry eye, and it's hungry for light.

I so I was like, oh, it was blind, it didn't dazzle. This to did not dazzle. I could shine the brightest light I had right in with only millimetres to the cornea, and it couldn't respond.

And it was blind. Now this is the blind horse here. Looks very similar to some of the other.

Fundus examinations that you've just seen. OK? Maybe we've got a little bit more dropout chorioretinitis out here.

The vascular pattern has been dropped more through here and, also up through there. But not very striking lesions. You wouldn't, I wouldn't look at that picture and say, oh, well, that's gonna be a blind horse.

But it was. Now maybe there was something else going on, maybe there are extraocular reasons for this horse's blindness. So you can't always say, oh yeah, that's definitely consistent with blindness.

Let's look at this horse, OK. Focal lack of pigment in here, it looks like this is the optic disc here, and it looks like it's got a second optic disc right there, and that's a coloboma. It's an atypical collarboma cause it's a little bit further from the, fissure of the eye than most.

And we've got some changes through the retina as well. Perfectly well sighted. Sometimes if these collar bomas are massive, and by massive, I'm talking greater than 2/3 of the size of the funders.

Then you can have problems with vision, but in this case, not. So incidental finding in an old horse. And so it's been there all its life, never did any harm.

And you can see here the vessels crossing it. So, it's doing quite well. Here, we've got a sort of yellowy, pale, optic disc atrophy, loss of vascularity and colour there, but again, not blind.

Maybe visual acuity down, but We can't assess that in a horse anyway. They don't read, so it really doesn't matter. As long as they can see the fence and they clear it by more than 1 millimetre, then the rider's gonna be happy.

Torpedo thinning. OK, you get a very prominent vascularity. You do get reduction in night vision when this is extensive.

OK. So, this sort of reddening comes through as the tapedin fades away. And that can cause reduced night vision in the same way that retinal depigmentation does as well.

So you see this in your Appaloosas, in some of them. So it's, it can be a problem, but again, Sometimes hard to assess just how much vision they lose. And in this one, we've got fairly extensive, this was chorioretinitis.

If the image is poor because it's right at the edge of the, the fundus. And in horses, that's actually quite important because they use the edges. They have a lot of, con, rods all the way down to the edges cause they pick up peripheral movement.

And so again, this is likely to have been associated with the reduction in visual acuity, but not to the point where you could have actually said, yeah, that horse is blind or that horse is more blind than another horse. I'm going back to our famous recurrent UVIS, OK, the bullet hole lesions of chorioretinitis. OK, this is one that's everybody talks about the butterfly lesions and the bullet holes.

If you've got one bullet hole, don't worry. The eye is very robust, the fundus is very large in comparison. And here we've got a little bit of a butterfly lesion starting to develop on the edge of the retina.

OK, in the other eye, this horse, we've got a little bit more retinitis there and we've got more, bullet holes. And this horse had had major problems with severe recurrent uveitis over a period of about 4 years. So, again, sometimes the severity of the UVI just doesn't lend to how much retinal damage you'll have, but certainly the more retinal damage you have, the more likely it is to be loss of vision, particularly of night vision in these horses.

And this is where we're talking about the stars of Winslow. If I'm unable to clearly focus on the stars of Winslow, yeah, I think that the lens and the cornea and the anterior chamber are clear. I wonder why.

And I did have a horse where I couldn't see it. And for the life of me, I couldn't get the stars of Windso into clear focus. They would flip past every now and again, but I couldn't get a clear focus on it.

You can see that the optic disc is in better focus, but the edges are lost, and then you can't get any real image behind. The camera just could not get an image of this. And the reason was that we had quite a severe retinal detachment.

And we've got the optic disc here, and the retina remains attached at the edge of the optic disc, and then it's full of fluid behind here, presumably blood or some other extra days. And we've got some real issues there. There were cataractal changes as well in this, not as severe, as the effect of the retinal detachment, which is, of course, complete blindness.

So Conclusions. Really, unfortunately it's gonna be a bit of a mixed bag here, I would say that horses with severe funic disease. Can appear normally sighted.

And unfortunately, that is the case. And sometimes your blind horses have little injury in the fundus. And it's just one of life's little mysteries as to why it doesn't relate much more directly.

And it is a problem. So often all we can say is that the horse is blind. And that there are abnormalities that may relate to the dysfunction, and that sort of gives us an excuse for saying, yeah, there you go, your horse is blind, you've got some changes, and let's move on because there isn't anything we're gonna do to fix that.

And then alternatively, we look at other abnormalities and we say, OK, well, these abnormalities are present, and they're either a major problem, they're likely to affect the behaviour and safety of this horse by affecting its vision, or they're a minor problem, and on the balance of probability, they're really of no consequence. And unfortunately, the truth often lies somewhere in between. So it is one of those things you have to make a bit of an educated guess, .

I tend to worry more about corneal and lens changes than I do about fundic changes, in a horse that seems to have normal pupillary light response and will dazzle. So unless they seem to have, affected vision, then I don't think that fundic lesions are that significant. Progression is always hard to predict, and so it is helpful if you've got a bit of an idea.

And do try and be conservative. I, it's about protecting yourself in practise. And if in doubt, record the lesions and send them on to somebody.

And you've got an idea of how to do that with a camera these days. So, thank you very much for, for listening. I hope that, it's helped you to put into perspective the pre-purchase examination of the eye.

Sean, thank you so much for that. That was hugely informative and I'm sure that all of our colleagues that are on tonight are going to have a much clearer idea of what they should be doing at the pre-purchase exam. Before we go on to questions, I'd just like to take this opportunity of thanking MSD once again for their very, very generous sponsorship of this series.

Folks, if you have a look in your chat box, Katherine has very kindly dropped in a link for you. That link will take you to the whole MSD series. We have got one left in the series, which is on Fal sepsis on the 4th of February, so not far away.

But all the other recordings are on that link as well. Go and have a look at it. The ones that you've missed, as you've seen by the quality and the expertise of, of Sean tonight, they really are worthwhile things.

And, MSD has really put their money where their mouth is and brought us some absolutely quality CBD. So don't miss out. Go and have a look at the website.

Speaking of the website, you can also have a look at our website, the webinar vet.com. We do have quite a few recordings on there as well, for those of you that are mixed practitioners, we have other species as well, a lot of small and, small animal.

There are some horse recordings on as well. Most of those you will need to be a member. The membership is, is a mere tuppence for the quality of the CPD you get.

And then on a night like tonight where it's absolutely blooming miserable outside, you can sit and listen to the expertise like Sean in the comfort of your own home. You can even have a glass of something a little fermented on the grape juice side if you want to, and nobody's going to be moaning about it. So once again, thanks to MSD.

We have run a little bit late, so we're not going to get to all the questions tonight. But Sean, let's just start and have a look at some of these. Kai wants to know, I often see the wrinkling in the backside of the cornea in corneal ulcer cases.

Is this the demon's membrane? Yes, it's, it is decimate's membrane, and particularly, on the ultrasound you can see that wrinkling. And it's a lack of, of pressure, within the anterior chamber.

And most horses, when they do have uveitis, develop hyperbaric uveitis. Glaucoma is actually very rare in the horse. And so with inflammation, it's more likely that the pressure will drop, then go high, and that's why we tend to see that wrinkling.

Excellent. You've just answered the next question, so that's fabulous. Another question comes up, when treating with dexamethasone in the eye, would there be a risk of the horses being doping positive?

Not in my experience, no. The, the levels tend to be low enough, but in general, people aren't, aren't treating at the time. They, they are, they do tend to be cautious.

They The one thing I would avoid is some people have a habit of putting depot, triamcinolone into eyelids. And I'm not saying that it's wrong because it does work in, in cases that that would swab. But, dexamethasone itself only has a 3 day withdrawal.

So I tend to tell people just stop for a few days and then continue on after the event. Excellent. Alistair asks here, is it always Y-shaped?

I sometimes see a small reflective lesion in the lens that can be diamond shape and looks like it is made of golden threads. What could that be? Occasionally you can get other shapes to it and you also get shadows as well.

But, in general, you'll get the sort of classic, sort of three-pronged effect, just because that's the, the way that the crystal of the lens, solidifies. Awesome Sean, as Anthony always says, the problem with doing webinars is that you cannot hear the thunderous applause. I'm sifting through the questions here and there are so many comments that have come in.

Thank you so much. Excellent webinar. Sean, that was fantastic.

Great lecture, excellent photos. Thank you so much. Sean, that was fantastic, brilliant slides.

And so it goes on and on and on and on. So there much appreciation pouring in here. Sean, we're just gonna take one more question here quickly before we wrap it up because we have run a little bit over.

And Tamara wants to know, would you consider sedating a horse for an an inverted commas proper examination, even though it makes the eye lazy and sleepy and therefore possibly makes making some interpretations more difficult. Even though the horse is not well behaved, owners still might be interested in the horse. Certainly you can do that after you've done the rest of your examination.

And for a clinical case, I quite frequently will sedate a, a clinical horse, particularly if you've got a sore eye, because it just makes it easier to, to do. So in a pre-purchase examination situation, I can think of a couple where I have, Done all the rest of the examination, then gone back to the eye, sedated them, and used tropicamide, at that stage to get a maximum view. And it, it can be useful.

Oftentimes it confirms what you already suspected, which is stay away from it. Fabulous. Sean, I'm afraid we have run out of time, although I would love to carry on with the questions.

More thunderous applause coming, pouring in here. From my side, I would just like to take this opportunity of thanking you for the time that you have given us here and also thanking MSD once again for their fabulous sponsorship.