Hello, so today's webinar is looking at bovine ophthalmology and also bringing into that where ultrasound can be of value to us in terms of likely success of treatment, if that's something we're considering. So I thought I'd start with just a reminder of what the normal eye looks like. So when we're thinking about the bovine eye.

That we've got that very oval pupil and like with other ungulates, when we shine lights in them, they've actually got a pretty slow pupillary light response compared to perhaps us and and and and dogs and cats. And then when we come to look at the back of the eye, the view on the left hand side that you've got on your screen is what we regard as normal. We've got this sort of Y or four pronged vessel that runs out the centre of the optic disc.

And again, unlike Some other species that optic disc isn't always myelinated and isn't always there for white in appearance. But what you can see is that that disc is pretty flat. We have a topey and a non-teal fundus just as we do in many of our other.

Veterinary species, and that there will be, you know, variable amounts of reflection, that reflection in that left hand picture is perhaps more pronounced because a flash was used to obtain this image. And then when we move to the right hand image of the retina, this, if you like, is a variation of normal. It's a very odd shape, which is, which, like I say, can be very normal.

And the reason for this odd shape partly is because we've got a hyaloid remnant, which is quite common and called Bergmeister's papilla. And this myelination is, like I say, a variation of normal and then these changes that we get right in the centre of where those large vessels join is that yeloid remnant. So now let's move on and think about ultrasonographic anatomy and very handily, ultrasonographic anatomy is very er similar to what you would expect it to be anatomically.

So we would normally scan the eye through the eyelid, which can be really helpful if we do have corneal disease. And the structure that's gonna be right at the top of your image is gonna be the cornea. Now, ultrasound isn't a brilliant way for, evaluating the cornea, but certainly we can see it, we can see when it's very thick.

And then below that we've got the anterior chamber. And then when we're imaging in the correct plane, we should then see the anterior and the posterior lens capsule. And like you can see in this picture on the left, they should be super smooth and sort of very echoic.

We've then got the iris sitting to the laterally and medially to the lens, and then we have the posterior segment, and then we see the retinochoroid unit as a discrete area. So again, it's not brilliant for evaluating retinal disease, but it can tell us about retinal and choroidal detachments. We can somewhat see behind the eye with retrobulbar muscles and fat, but even with exophthalmus cases where you suspect there might be a tumour or an abscess behind the eye, it isn't always that easy to really interrogate that with with ultrasound.

And I then wanted to just highlight that, you know, we all get very used to looking at cows have got brown eyes. And this was a study conducted not that long ago, looking at heritability of this iridial hypopigmentation. And like the one in the sort of image at the bottom, you can see that that hypopigmentation in this, in this cow is bilateral and is affecting the whole of the iris.

Whereas if you look in the picture on the right hand side at the top, you can see it's just impacting on particular areas actually isn't symmetrical between and between eyes. And these this aridial hypopigmentation, we do know is heritable in Holstein Friesians, but it doesn't seem to impact on on vision. So I've sort of put that if you like into variations of normal.

So I now thought that we would move on to thinking about disorders of the cornea. And unsurprisingly in cattle, these are predominantly infectious, and we can see changes with both the cornea and other other parts of the eye with BVD, malignant catyal. Fever, Listeria, TB, toxoplasmosis, and then sepsis, particularly secondary to diarrhoea and calves, but we can also see ophthalmic manifestations of sepsis in adult cattle, secondary to things like E.

Coli, mastitis, metritis, etc. And then obviously the other group to consider are the neoplastic causes of disease that we see, which predominantly in cattle are squamous cell carcinoma in the UK but we can see changes with both spontaneous lymphoma in cattle, and then in other parts of the world, secondary to a bovine leucosis virus. So I thought I'd start with this, and when you read lots of textbooks talking about manifestations of ophthalmic disease, they make it sound like it's really, really easy to work out exactly what condition you've got and how you're gonna treat it.

What I'm hopefully gonna show you is that to some extent, we can have some pointers as to what that likely disease is that's going on, but equally, we can get many of these non-specific changes with systemic infection and inflammation. This image on the left hand side is a thromboembolic, secondary, sorry, to a thromboembolic meningoencephalitis caused by Haemophilus somness. And what you can see in this picture is we've got the, we've got a very, very marked conjunctivitis.

We've got corneal edoema giving us that sort of sort of blue glass appearance to the surface of the eye. We've got hyperpyon or pus sitting in the anterior chamber. And then we've got this sort of radiating neovascularization running all the way, around the edge of the cornea, sort of in that limbic region.

And just remember, think about that picture in a minute when we, when I show you some pictures of some specific diseases and how they manifest in the eye. This image on the right is taken from a calf that's got E. Coli, diarrhoea and sepsis, and again here you can see actually this calf's got uveitis, if you look really closely, you can see that the pupil's constricted and that we've got this sort of corneal edoema as well.

OK, so we're now gonna move on and talk about IBR, infectious bovine rhinotracheitis. And what I've got here is that we know that IBR results in a severe, usually non-ulcerative curratoconjunctivitis, and we see we see these diseases with other herpes viruses in other species as well. So if you look at the images that we've got here, these all look very, very different in terms of their presentation, despite the fact we, it, the underlying cause was confirmed to be the same.

So when we look at picture one, we've got in this cow that we've got a, which is, which is actually the, A picture, my picture's muddled up. My, the picture on the right shows a sort of quite early stage of disease. It's got bilateral uveitis.

You can see that the pupil's really, really small. And remember that those constricted pupils result in, moderate to severe ocular pain. We've got some mild corneal edoema, we've got And we've got some injected conjunctiva, so not really severe, but you know, pretty, pretty obvious that that's where, where we've got.

And we've also, if we look at that picture on the left, we, again, we've got uveitis, you won't be able to see that from the picture, but you can see we've got this sort of really marked, conjunctival edoema sitting on that surface. And then the horse, the, the, the image that we've got in the middle is a uveitis with very marked corneal edoema, and you can almost see really hard from an image to know whether that sort of. Change in surface, if that sort of unusual appearance ventrally is a change in the the smoothness, if you like, of the cornea or whether we've actually got deposits sitting in the anterior chamber.

But when we go back to that picture on the left, this was an outbreak of IVR alongside animals that had got respiratory disease. And when you took samples from the, from the surface of that conjunctiva, there was lymphocyte infiltration. Surface necrosis, but more interestingly, not all of the animals in that group looked the same.

Some of them had uveitis so looked like the image on the right, and others had keratiti, so looked much more like the case that's in the middle. And in terms of management of these cases, often, as we know, it's non-specific, really, really beneficial if you can give these animals non-steroidals because of the welfare implications of the ocular pain. And then we know, particularly when we get curratoconjunctivitis.

Compromises the surface of both, obviously the conjunctiva, but also the cornea, and that's going to make it at risk of secondary bacterial infections, which we might need to, we might need to treat and manage in order to prevent development of of ulceration. The next disease that will manifest with corneal change that I'm gonna talk about is Listeria monocytogenes, which obviously colloquially we call silage eye. And that you can see here, again, we've got some of those changes that I showed you in that, in that sort of non-specific disease manifestation in those slides a few, a few slides ago.

So with Listeria, we'll often see epiphora early on in the disease. See that the cattle are photophobic. Again, they get corneal edoema, and they also get that circumferential neovascularization that we can see with any form of sepsis secondary to corneal manifestations in in cattle.

You can also see in in this case, we can sometimes get this sort of yellowing change with presumably ongoing and and involvement in other secondary bacteria, leading to this sort of greeny yellow appearance of the cornea making it look pretty unhealthy. And in terms of prevention, better quality silage, as we know, is always gonna help reduce that risk of any forms of disease with Listeria, and also opening the, the silage when it's wrapped a few days prior to feeding. In terms of treatment, treatments, treatments regarded, there, there's been a few studies looking at, best practise when we're managing these cases, and some say it makes no difference whether you use subconjunctivaloxy, tetracycline, and steroid.

And others say that actually it will prolong the period to heal if you don't apply treatment. They might need that subconjunctival combination more than once depending upon the severity of the ophthalmic disease. The next condition that we're gonna talk about is IBK, so infectious bovine, curratoconjunctivitis, or again, colloquially known as pink eye, and the underlying organism for this is Moroella bovis.

And again, we've got this sort of range of manifestations of this disease, depending upon the stage that it is and also how severe the disease becomes, which is somewhat related to the immune response or lack thereof of the immune response. So when we look at the picture on the left, we've got a pretty uncomplicated early IVK. The lesions in this case where they're causing this sort of ulceration are usually medial.

We then moved to the image in the middle which gives it its name, Pinkeye. This is much more complicated, this case. We can see we've got quite a severe and deep ulcer in the centre of the cornea, that has resulted in a desert.

Metace, which is the, the sort of black bit and then the, the white part to the side of it that you can that you can see. And again, we've got that really marked radial neovascularization that cows do so well. This was actually, this was actually in a, in a pretty valuable cow that they wanted to try and save the eye.

So in fact, we did a pedicle graft on this one in the centre, and although it was left with a small scar in the middle of its cornea, it did in fact it did in fact keep its eye. And then the image on the right is actually taken from a calf that had got glaucoma, secondary to IBK you can see it's got this blue appearance, and it had, Incredibly high intraocular pressures and cows do this really cool thing with their eyes, they get this sort of marked granulation granulation tissue response, which is why you get that sort of Scarring if you like, whiteness on the surface of the cornea that's in the centre of that image with the sort of bluish corneal edoema around it, and again worth remembering that, Glaucoma's a really painful condition, and you know, treatment options with these with these animals depending what jurisdiction you're working in is in nucleation if it doesn't look like it's gonna resolve quickly, management of the pain with non-steroidals, and if you did want to keep the eye. Options are available and have, have been described in, in other species of using intravitreal gentamicin.

Gentamicin has got MRLs for both meat and milk in in Europe, so has to be used with caution, but we, we do know, we do know withdrawal times. And then when we think about IBK we often find it in outbreaks, we'll have groups of animals which obviously has both welfare and financial implications. We know it's transmitted via flies, animal handlers' hands, and also direct.

And infection rates will vary by season, usually higher in calves than in cows, and older previously exposed cattle will usually get milder forms of disease, presumably because we know immunity develops and then will persist. And then we move on to onto M M bovis. And here we know that again, you can see from this range of images that we have that we've got again this sort of variety and variation of disease.

We know that with this condition we have got. It's a multifactorial disease and that we will have various factors that will impact on both the severity and how many how many animals are, are affected. We know that UV plays a role because it leads to degeneration and increased sloughing of epithelial cells which promotes attachment of the organism.

We know that animals that have got less pigmentation, like the one on the right hand side, are gonna be at higher risk. And also, at times where we've got, that it's very windy, or we've got a lot of dust or tall grass, we know that they will be physically irritant to the ocular surface. And the last risk factor is concurrent infection, particularly with IBR or a recent live vaccination to IVR and this seems to increase both the severity and the prevalence of disease.

As well, we know that Mycoplasma also promotes colonisation. So when we look at the ocular manifestations of this disease, if we start on the left hand side, this is a an animal showing a very marked scar indicative of previous infection, and you can see again that this cornea is incredibly scarred because of the because of the marked inflammatory response that previously occurred. This one in the centre is sort of nearly healed, if you like, that you can, you can see we've got again, that marked radial neovascularization that's almost joined in the middle.

And then the one on the right hand side, this is a sort of milder scar that you can see, and you can see we've got that sort of, you know, more white colour of the cornea sitting in that, in that medial, canvas. So no ophthalmic talk would be complete without talking about the ocular manifestations of malignant cataral fever. And as we've said before, herpes virus, although different types manifest in different ways, and they often do have in, in all species will have some forms of change that we can see in the eyes.

So when we're talking about malignant catal fever, we often see corneal edoema, as you can see in that bottom picture. You can see we've got increase in vascularity of the limbus and and mild conjunctivitis. But if we could look into the eye, we would be able to see that these animals.

Have got uveitis and have got meiosis, as well as all of the other systemic manifestations that you can see in the care in the top picture, but the ocular component of this disease again is pretty painful. And then we move on to blue tongue, and again we'll often see corneal edoema with blue tongue, particularly in calves that were infected in utero. And the blueness in the corneal edoema is actually a temporary condition caused by a type 3 hypersensitivity.

So you normally find that these animals are PCR positive for bluetongue virus, they, Were infected in utero, and then they received immunisation via colostrum, and this combination of having both antigen and antibody complexes circulating results in deposits of these complexes on those epitheliotrophic organs, so that includes the kidneys and also the eyes. These complexes attract neutrophils and enzymes which results in these these, this manifestation. Usually if they, once they recover, the blueness and the of the eyes and the corneal edoema resolves within sort of around about a week.

And then the last cool condition that I wanted to talk about in terms of things that we see on the corneal surface were dermoids. And dermoids are an inappropriate growth of hair on the corneal surface, and we always have to remember that the cornea is a special form of skin, so if . It developmentally, if it's development doesn't follow the routes that it's supposed to, it can result in being skin.

So here's an example of a dermoid in a jersey calf. This calf also had some mild conjunctivitis, and if these are causing a problem, which they often do because they grow bits of hair, they can be pretty easy to under a local block and some topical local anaesthetic, and they can be removed with a partial keroectomy. And then the last disease to talk about and its various manifestations impacting on the cornea are squamous cell carcinomas.

And these squamous cell carcinomas usually start at the lateral campus, which is what you can see in both of these images. The one at. Top is a very early form, and you can just see some some changes, some skin changes, and also some sort of vascular changes beneath that, on the limbus.

And then the picture at the bottom is showing that sort of more classic cauliflower appearance where it's a little bit more developed. Occasionally, when they haven't started at the lateral campus, you find that they might begin on the 3rd eyelid, which has got lots of advantages because the 3rd eyelid is pretty easy. To resect.

We know that in susceptible breeds, we've got 10% that will be bilateral, and 30% of animals will actually have multiple lesions. And as we've said, it's usually those animals that have got little to no pigmentation around the eye that seem to be at risk. And these would include Herefords, Hereford crosses, simmmentals and short horns.

And again, like we talked about with M. Bovis, it's a multifactorial disease. There's a UV component, there's a genetic component, and then there's also the hypopigmentation.

And as with other species, we know that there are usually precursors to them becoming the squamous cell carcinomas. And in those early stages, there'll be these benign raised, white, hyperplastic plaques, and, and sometimes we'll start off as papillomas. We know that about a third of these precursors regress, but that we also know recurrence can occur in exactly the same place.

Metastasis of this tumour is pretty late in its disease process as we as as occurs with other species. And invasion of the globe is actually pretty rare. It can happen, but it's much easier for the tumour to grow outwards than to grow through into the cornea.

Now in an ideal world, we would reset these when they're small, and actually you can, it's not, again, a difficult procedure to perform, you do need some relatively fine instruments, but again, with local blocks and topical local anaesthetics, when they're in that region of being pretty small, you can remove them, you leave the animal with an with an ulcer that will that will heal with minimal amounts of involvement. The other thing to be aware of, and again this is in, in, in other species, is that we know, these sort of cellular carcinomas are sensitive to a drug called peroxicam, and there have been some studies in both horses and to show that actually meloxicam can have similar results and. I've certainly used meloxicam in a, in a cow with an early squamous cell carcinoma, where we did see resolution of signs.

You can often get away with using the meloxicam at lower doses and at longer dosing, intervals if you want to try and control this disease for, for, for specific reasons. And then these are some images of more advanced, more advanced squamous cell carcinoma, that we can see. So the two that I showed you on the previous slides would be very easy to, would be very easy to, to resect in practise.

The two images at the bottom here are starting to become pretty invasive. The one at the bottom left looks like it's starting to invade the, the eyelid, which is when life becomes pretty challenging because we lose the integrity of the eyelid, we lose protection of those eyelids. The one in the top left has just covered the whole of the surface of the eye and really there's gonna be very little other than in nucleation if needed to be able to manage that.

And then this one top right is a real problem because it's caused defamation and splitting of that . Of the lower eyelids, which is certainly gonna comp is gonna compromise integrity of that eyelid and being able to protect the eye. And then the last image I wanted to show in this section was a lymphoma, and in fact, this was a spontaneous lymphoma, not one caused by bovine leucosis virus in the UK.

And what you can see here is that you've got this very marked conjunctival swelling, and we might expect. To be able to see that with with allergic manifestations of allergic disease in the eyes. But normally if you've got er some form of, of allergy resulting in that degree of inflammation, you would expect there to be high femur and also epira.

And this condition was bilateral, and this animal did also have a peripheral lymphadenopathy. So we've got this sort of conjunctival swelling because we've got a neoplasm behind the eye. OK, so the next section we're gonna move on to is looking at disorders of eye position.

And these are relatively common in cows, perhaps compared to what we would expect to see in other species. And the first condition we're gonna talk about is convergent strabismus. And this can be associated with either an exothalmus, as you can see in this sort of Hereford cross that we've got in the top.

So that right eye you can see is exophthalmic, whereas the left eye is actually microophthalmic. And what you often notice is that the eye is rotated, permanently rotated. Ventrimedly, doesn't have to be ventromedial but it often is, and that their eyes are sort of convergence, so they're sort of looking together, making really impacting negatively on on vision.

We see it in jerseys and short horns and then less commonly in Ayrshires, Holstein Frisians and brown Swiss. We know that it can be secondary to congenital hydrocephalus and also to sort of those neuro-ophthalmic congenital manifestations of BVD. And this was again another case of a hereditary strabismus.

And it's pretty, pretty marked, that strabismus, that this cow is gonna have a very poor ability to be able to see or focus. And when we ultrasounded this eye, which we did to see, what, what lay beneath, hopefully you can see the eye's always gonna be rotated, but the lens in this, the lens in. In this image, hopefully you can see that with my pointer is off over to the right hand side, but you can also see that we've got actually here a very focal but quite large posterior capsular cataract.

So this is this is one of those, one of those cases where you look at it and you think actually there's there's other manifestations of ophthalmic disease going on in this case. Now, the next case is an interesting one, and I, I apologise that these pictures aren't totally sharp. This was an incredibly, dark area where this crush was.

So, you initially look at this, this eye, we were asked to, to, to look at this. The farmer was concerned, the eye had looked like this for a while, but that the animal had seemed to become, a bit. Bit less normal, I suppose, she wasn't, she wasn't coming into the parlour in the same place as usual, he was worried that she'd got some low grade pain and he thought this eye was perhaps bulging more than it had before.

And our initial look at this eye, you look at it and you just think, this eye has just got really severe scarring and secondary to one of those infectious ocular manifestations we talked about at the beginning of the talk. She's got this sort of, you know, perhaps this piece of granulation tissue in the centre, and that, you know, the, the corneal scarring in this case has resulted in melanin deposits, which is why it's black. But then what became very evident when you touched this eye was that you could sort of rotate it in a very, in a very abnormal way.

So you looked at it and you're like, well, it looks an an exophthalmic eye, you wonder how painful it is. And then. When we actually imaged this eye, this is another one that's got a posterior capsule, a cataract.

When we imaged this eye, you could actually see this was the back of the eye that was nearest to us. And that, in fact, the lens and the cornea were, were deep in. So it appeared that this tissue that we've got here was in fact the optic nerve that had been severed, and the reason that the cow's eye could spin, as it were, on a sort of horizontal axis, was because it had presumably damaged or for whatever reason, not had that they weren't normal, it had damaged some of the extra ophthalmic muscles that usually support its position.

This eye was glaucomatous, and so we recommended that this eye needed a nucleating for for welfare reasons as it probably was pretty painful. So we've talked about some of the abnormalities of eye position. We're now gonna talk about some of the diseases that affect the anterior chamber and the lens.

And I've sort of already talked about some of the ones that affect the anterior chamber. That lead to corneal edoema, because where you've got meiosis and corneal edoema, they're sort of gonna overlap, and obviously leading to hyperpyon, and fibrin in the anterior chamber. So I thought that we would just do a quick overview of the uveitis, we've already talked about it, in terms of, some of it to do with specific diseases.

But we know that uveitis occurs secondary to corneal, systemic disease, which is usually bilateral, and also to trauma, which is usually unilateral. And cows don't always appear as overtly painful as other animals when they've got UVI. They certainly can do and have photophobia, leprospasm, and epiphera.

But sometimes they look like they're quite comfortable and the eyelid's not necessarily closed, but it's likely to be, certainly likely to be the underlying pain involved with that. So as we've said, we see corneal edoema, we see this deep corneal neovascularization, which is radial. We get aqueous flare all the way to hyperpyon.

We can get swollen irises which actually are often very difficult to appreciate because we've got corneal edoema in the way. We've got meiosis, which you can just about see in this picture, assume when you've got corneal edoema, you've got meiosis and pain, and then we can also. If we get to the other side of that disease process, we can end up with posterior syche formation and cataracts, which will again impact on vision and the ability to cope in different forms of light.

We know we can see it's secondary to sepsis, both with, in neonates. Usually that's gonna have manifested as diarrhoea, but also in adult cattle, secondary to severe mastitis, metritis, traumatic reticulitis or reticulo pericarditis, MCF, TB, IBK, thromboembolic meningoencephalitis, which is, what this case is here. Leptospira, toxoplasma, Listeria, and occasionally lymphoma.

And in terms of generic management of uveitis, topical and systemic antibiotics, topical midriatics in the form of atropine, and we know from EMA regulations that atropine's got no, no need for MRLs because it's . Metabolised actually probably doesn't enter the bloodstream but is metabolised very, very quickly and non-steroidals. And those latter two really important in terms of managing discomfort and pain associated with ophthalmic disease.

So I apologise for the flash that's on the middle of this picture, but hopefully you can see that this is a a case, this animal probably had ophthalmic disease several weeks to months ago. And you can see that we've got a cataract in the middle, sort of cloudiness in the middle of the iris, and then we've got all of these black pigments and strands, which are connections between the iris and the and the lens resulting in . These posterior sinki, and I mean this cow's gonna have minimal vision in this eye, and it can be variably painful after these episodes from nothing to continued mild levels of pain.

And then these are some images that we've got of cataracts. So the top left-hand picture is a cataract, very developed cataract in a in a. Young Hereford calf and these cataracts were bilateral.

And interestingly, the dam of this animal had also got bilateral cataracts, making it more likely to be an inherited form of disease. And we know that we often see these inherited cataracts in jerseys, Herefords, Holsteins, Shhorns, Holstein Friesians. And that that abnormal cataract development can also be associated with other ocular inherited ocular abnormalities that will include the lens being displaced, although that may just be a manifestation of an abnormal and a larger lens than there should be, but can also be associated with microphthalmus and ethalamus as well.

In short horns, there's a, a combined, unfortunate combined condition of of of an inherited condition of cataracts which are seen in conjunction with hydrocephalus, cerebellar hyperplasia and myopathy that are not related to in utero infections with BVD. And then the second form of of cataracts that we can see in animals are those that are congenital. So, we know that we can see those with BVD if they're infected in utero at a time when that.

Neuro-ophthalmic system is developing and there are some reports that sort of question whether or not we can also see congenital cataracts with bluetongue virus as well in utero, infections of bluetongue virus. The ultrasound image at the bottom was actually taken from a, a jersey, and this animal had got a very focal, nuclear cataract. And this animal could actually see, you could image the, cataract when you used an ophthalmoscope, but the, the actual, Lens itself certainly didn't have this this sort of ground glass appearance in the way it does where you've got these much more marked inherited or congenital cataracts.

I mean this is likely to be congenital, but it just was wasn't very severe. And then this last picture was one just showing some we can get some persistent pupillary membranes. And these are pretty rare congenital abnormalities, and I haven't got a picture of one, but they can appear very similarly to posterior sinkier post inflammation, which is what this picture is then.

You can see this sort of spider web connections here passing from the iris down to the surface of their lens and this this animal has also got a capsular cataract, and when you see this, you know that this animal has had previous uveitis, but those persistent pupillary membranes that you can see, they have a sort of very similar appearance. And then the other thing, I showed you those pictures at the beginning of that sort of iridial hypopigmentation that doesn't seem to impact in Holstein Frisians on vision, but these are two, other manifestations of changes in Irish colour, where in these particular cases, it did. The image on the left hand side is from an albino jersey calf, and this animal as well as having this appearance to the eye.

And you can see that this animal has got a very meotic pupil. The animal also had nystagmus and had photophobia. So there were other ocular and neurologic abnormalities that were going on with that animal.

And this second picture here, this is obviously an incomplete albinism, this is actually from a Hereford, and you can see that incomplete and that change in colour of the iris that we've got down here in this sort of ventral portion. And this again was this animal also had other ophthalmic abnormalities and didn't appear to have totally normal processing of vision, from this on. So then we move on to the last section of this talk, which is looking at disorders of the posterior segment.

And . Many of these we're gonna discuss are going to be changes that we can see if we ever look into the into the eyes of, of cattle and gonna be retinal changes. We're gonna start with retinal collarboma because they're pretty cool, they're pretty common in cattle, and we know that in Charolets they're inherited, as a dominant trait which has complete penetrance in balls and incomplete penetrance in, Tackle.

They're usually symmetrical, but they are, sorry, they're usually bilateral, but they're not usually symmetrical. So you can see here in this top image that the the part that I'm just highlighting and the sort of the, the dorsal part of the. Of the white part of the image is the optic disc and that looks pretty normal, and then we've got this abnormal tissue with a little bit of hyperpigmentation at the bottom, and coloboma means absence of tissue, but you can see that actually this, this, Cow's got pretty normal vessels, that's got a hyaloid remnant in the centre, but probably that's gonna have minimal impact on vision.

And this is the, this is another one down at the bottom. So you can see this is the normal optic disc at the top, and then this is the abnormal collarbone mirror at the bottom. And then the other thing that we see, just as we see with the cornea, we also, we can see marked retinal changes with secondary to systemic disease.

And so what we've got here, this image here is a choreo retinitis in a. Young heifer, so you can sort of see we've got, they look like little worms, but they're not worms, but we've got sort of degeneration of this, to people fundus, and, you know, sort of choreo retinitis, we've got some changes up here, that connect with the, the optic disc. Up here we've got some haemorrhage in a yearling steer that also had acute neurologic signs associated with thromboembolic meningoencephalitis.

And these haemorrhages result from damage to the end on choroidal vessels. And then this image down at the bottom here actually is a bullet retinal detachment, so we've got multiple haemorrhages that we can see down in the bottom part of the image, and then you can hopefully just see that this part of the This part of the retina in this topial region hasn't got the same reflectivity, it's probably sitting in a slightly er different plane. And this animal had got clinical signs of vestibular disease as well, but responded really, really well to antibiotics and continued being able to It continued having, having vision and the, the haemorrhage obviously resolved.

And this image in the centre, this very green image which is focused on the tapeta, actually was secondary to a, a streptococcus sepsis in an adult guernsey. And you can see we've got this sort of really odd change in, colour and pigmentation of the, of the torpedal fundus. So sometimes looking within can actually give us .

Give us information. And that then sort of moves me on to vitamin A deficiency. I certainly have been involved in a few outbreaks of these, sometimes with concurrent vitamin D deficiency as well, and vitamin A deficiency can have two different manifestations, and that depends on the age of animal and when they were exposed to that lack of vitamin A.

Where you get calves affected, they will often, in utero, they will often develop bilateral optic nerve hyperplasia, whereas in older cattle that if you like, it's an acquired condition, they will exhibit papilla edoema, which is what you can see in this . Top image up here where it's got, if you like a sort of fuzzy edge to the to the optic discs, it actually got slightly small but it does have the presence of normal ish blood vessels. Or alternatively you can see, retinal degeneration, which is what we've got in this bottom image here.

This was a chronic deficiency in a steer. Again, we've got some evidence of papilledema, but we've also got this sort of loss of pigment sitting down here in that non-typeral fundus. And we know that low maternal development causes sorry, low maternal vitamin A causes abnormal bone development in a reduced diameter of the optic nerve canal, which can then result in optic nerve hypolate.

And then blindness in calves. Whereas in those growing and adult cattle, low vitamin A causes increased CSF pressure, the papia edoema, like you can see in these pictures, and then the retinal degeneration, like you've got in this bottom image. And if you were looking at this bottom image and you'd looked up and you could see the topeal fungus, you often find that there's increased reflectivity, which I'm sorry, is, is maybe slightly visible at the top part of this picture, but it's not completely clear.

And we can measure plasma vitamin A concentrations for diagnosis, and we do know that parenteral vitamin A, in adult cattle at least can be successful if that retinal degeneration's not too advanced. And then the next image that I'm gonna show you, I'm gonna show you because it's really actually just very, very cool. And this was taken from this image was obtained from a calf, and that had got cyanotic, that was cyanotic and on clinical exam, secondary to some complex form of congenital, cardiac disease.

And what you can see here is Because this animal's been hypoxic for a few weeks, it's become, polycythemic. And that polycythemia has led to, lengthening and really a large and tortuous, vessels sitting at the back of the eye. I mean, obviously, there was no, treatment for this animal, but, the image was, pretty cool to obtain.

And then just to finish off, I said we'd talk about the value of, of ultrasound, and ultrasound really comes into play where you've got corneal edoema, and you want to know whether or not it's worth trying to treat the eye that you've got and manage the pain and welfare implications that come with that, or whether actually we know that that eye is probably pretty . Unlikely to result in a positive outcome and a comfortable eye. And these are two different ultrasound images taken from animals that have got corneal edoema.

In fact, both of these images came from animals that the ophthalmic disease was regarded as likely traumatic in origin. So let's start with this image up on the left-hand side. So you can see here, we look like we've got increased ecogenicity in the posterior segment, we expect the posterior segment to be largely black.

And we can also see that we've got this we've got this wavy line, for want of a better word, we've got this structure sitting within the posterior segment that we shouldn't be able to see. So the question with this eye is, is this inflammation or does this animal have a . Have a detached retina, cos if this is inflammatory, and there's a good reason why we want to save this eye, then this will probably resolve with appropriate treatments.

Whereas when we move on to this eye on the right hand side, you can hopefully see here, we've not got that really nice sharp edge to the lens, so we look like we've got a cataract. And we've also got this sort of V-shaped or seagull sign, of a, a pacification in the posterior segment, which is as pass. Mnemonic as we can get to having a retinal detachment.

So this eye is A, not visual now, B is never going to be visual. So it might help with our decision making of what we're gonna do, especially if we've got corneal edoema. Let's, let's not get too excited about trying to, trying to treat or manage that eye.

So in conclusion, we know that ocular disease is often painful and therefore non-steroidals, topical atropine, or renucleation, which could be physical or chemical, should be utilised in order to ensure optimal welfare. We know that many corneal conditions, especially those with an infectious aetiology, can look quite similar, perhaps more similar than the textbooks er allude to, and that we can use ultrasound, particularly following trauma, or when corneal edoema is present to aid with decision making and management of those eyes. And with that, I will thank you very much for your attention.

If anyone has any questions, please feel free to email me at gay.Hallowell@ IVC Evidencia.com.

Thanks very much indeed.