Good morning, good afternoon, good evening, wherever you may be. Welcome to my second talk of 2022. A couple of months ago, I have lectured about unusual diseases of the feline cornea, and today I'll be lecturing about unusual diseases of the uvea.

Yes, when we talk about UVR we automatically tend to think about UVIT and rightly so, cause that's the most common disease of the UVR. However, as you can see in these pictures and as I will be lecturing today, it's really not just UVITs, there are other UVL diseases that you should consider. Just to get us started, one brief, one slide devoted to a brief anatomical review to remind us what's the UVR.

So you can think of the eye as a globe consisting of three layers. In blue, we have the outer connective tissue that's the cornea up here continued by the sclera more posteriorly. We have in red, the innermost layer, the retina, and in yellow, we have the intermediate layer which is the UVa consisting as you can see here of the iris, ciliary body and choroid.

So this would be both the vascular and muscular layer of the eye as opposed to the connective tissue in blue and the neuronal tissue in red. We tend to divide the UVR into two parts. We are talking about, excuse me, anterior UVA, which consists of the iris ancillary body here because they're so intimately connected to one another and then there is a posterior uvea associated with the retina.

In fact, supplying blood to the outer layers of the retina and here in this diagram you can see what I mean by supplying blood to the retina, the rich vascular supply of the UVA and that's why, as I said, we call it a muscular layer and a vascular layer. Even though the topic of this talk is that The UVA is not just about UVITs. I really feel I can't give a talk about the UVR without devoting at least a couple of slides to UVITs cause it's such an important disease in ophthalmology and really it's such an important disease in veterinary medicine.

And I say that it's an important disease in veterinary medicine cause I want you to think of uveitis as an ocular lymphadenopathy, an immune reaction of the eye to a systemic disease. So just like systemic disease can cause lymphadenopathy of the submandibular lymph nodes or the pre-scapular lymph nodes, it will cause ocular lymphadenopathy. It will cause uveitis.

In fact, UVitis may be the presenting complaint of many, many systemic diseases and therefore, it is a clinical sign, not a diagnosis, just like you find lymphadenopathy of the submandibular lymph nodes, you don't say, aha, I have a diagnosis. If you diagnose UVIis, you don't go ah. I have a diagnosis.

No. In both cases, you work up the patient to determine the primary cause of the lymphadenopathy or of the UVIis. Once you find the primary cause, you treat it and you treat the eyes with anti-inflammatory drugs, with a topical or systemic steroids depending on the systemic condition.

Whether or not the cornea is ulcerated, in which case obviously you'd move to non-steroidal drugs and whether it is anterior or posterior vies cause topical drugs are only indicated in interiorit, they will not reach the posterior segment of the eyes and please don't forget to give atropine to all of your UVITs patients. Now, I say that UVitis is due to, is caused by systemic diseases and here is one study from North Carolina State University looking at 120 cats supporting what I've just said. These cats were worked up for systemic disease and as you can see, almost a quarter of them had toxoplasmosis, FIP at 15%, FIV and FELV at 10%, neoplasia at 5%, but the worrying number is this 1, 41% of them were idiopathic despite the Extensive workup in North Carolina State University and really idiopathic UVis is the most common diagnosis both in dogs and cats.

You still have to do the workup because you won't know if a patient has Toxo or FIP or some other disease, but be prepared that many times you'll come up empty-handed. This ends my quick review of UVITs and if you want to hear more, I invite you to watch the webinar archives. I gave a talk about it January 19, 2019 talking about UVIDs.

As I said, the take home message is that it's clinical sign, not a diagnosis. But going back to the picture of this cat here that you were seeing with UVITs, the question is whether you can think of an additional differential diagnosis in this cat other than UVITs. And if we were together in one room two years ago before COVID came into our lives and introduced us to Zoom, I'd ask for a show of hands.

So if you want You may pause the recording for a second and think of another differential for this and hopefully most of you thought of an intraocular tumour and really tumours should be suspected in every case of unilateral uveitis, unilateral hyfema and or unilateral glaucoma in elderly patients. Which brings me to the first topic of my talk today, which is intraocular tumours or uveal tumours. And the UVR just like any other tissue in the body, can be affected by primary tumours that originate in the UVA and may be affected by secondary tumours that metastasize to the UVA.

So looking at primary tumours, melanoma that you're seeing here in this dog is the most common tumour in both dogs and cats, followed by adenoma and adenocarcinoma. And unfortunately in cats, we also have a fair number of intraocular sarcoma and we shall discuss all these three tumours. And looking at secondary tumours, lymphoma is the most common secondary tumour to the eye and as you can see in this picture here, and in fact, the eye is the most common target organ of lymphatic tumours outside the lymphatic system.

So before they metastasize to any abdominal organ or any other organ, they will metastasize to the eye, but we're talking about secondary tumours, so anything is possible. Anything can metastasize to the eye. But starting things off with primary tumours and starting things off with melanoma, I think that melanoma is one, another classic example of the famous saying that I say again and again in these talks, a cat is not a small dog.

I've said it in my conjunctivitis talk with Work up and treat our canine and feline contivitis patients in different ways. In fact, I think I gave a whole talk, titled The Cat is not a Small dog cause there are many, diseases that we see diagnosed and treat differently in cats. As I said two months ago, I gave an entire To devoted to unique diseases of the feline cornea like cornea sequesttrum, etc.

Etc. And melanoma is another classic example cause the fate of these two patients, the prognosis of these two patients is completely different. In dogs, melanoma, may be malignant, but even if it is malignant, it progresses very, very slowly.

It rarely metastasizes and dogs can live for many, many years with Uveal melanoma. Unlike this cat with diffuse iris melanoma, where the prognosis is much worse, here is a paper looking at feline melanoma and you can see that they had 16 cats with intraocular melanoma, 10 of the 16, 2/3. Really were killed because of the tumour within 6 months and only 4 are surviving 255 days, which is less than a year.

OK. Speaking of ocular melanoma, I must mention palpibrar melanoma, which as you can see, is also a nasty tumour with a life. Expectancy of about a year and a half.

And again, going back to uil melanomas, metastasis occur in 2/3 of the cats. Now, I realised this is a paper from 1988, but unfortunately, not much has changed since then. Obviously, our oncology.

Care to many patients has improved both surgically and using chemotherapy, but unfortunately, it's not, we haven't made much progress in the treatment of iris melanoma in cats. So really it is a very, very nasty tumour and as you can see, carries a very grave prognosis, which means that when you diagnose Intraocular or uvial melanoma in cats, you should really nucleate the patient as soon as possible and pray that the tumour has not yet metastasized because you can see the hy metastasis right here. But we have a problem in cats that I'm sure you're aware of in that there are differing degrees of Melancytic lesions in the feline iris.

Some of them can present with this lesion here which is just a freckle. It's benign hyperplasia of normal melanocytes. Not a problem, and you can see here indeed it's a very quiet eye, no UVis, no glaucoma.

The cat can live forever with this freckle here. Unfortunately, sometimes these melanocytes will proliferate and will form a slightly elevated uveal mass which we call a nervous and these nerves may even transform into be benign melanocytoma. Which eventually can transform into malignant melanoma, which is what we are seeing here, where the melanoma is now involving most of the iris and if you look closely, you can even see melanocytic cells on the anterior lens capsule, which means That this eye really should come out.

It's probably even somewhat too late because you've got cells, melanoma cells floating in the interior chamber. Some of them have adhered to the interior lens capsule, but some of them unfortunately probably made it through the corneal angle to Venous circulation and metastasized to God knows where. But really, we have a problem here cause not every melocytic lesion in the iris or in the feline iris is, malignant.

So the question is how do we decide when to take out the eye? When do we want to, nucleate? And the problem is that jeez, there are numerous histopathological markers and biochem.

Markers, to determine malignancy, you can see lots of studies of immuno histochemistry of various biological markers for malignancy, but obviously these are not used routinely in our clinical work. So the question is what can we do as clinicians when we are presented with these feline eyes with melanocytic. Lesions and how do we evaluate them?

How do we decide when to remove the eye because we suspect melanoma and when do we leave the eye in place cause we think it's a benign melanocytoma or a nervous or a freckle. And the bottom line is that this, there is no clear cut answer to this dilemma and indeed it is a very big dilemma which is demonstrated by this amazing study from UC Davis. Unfortunately it was only presented as a meeting abstract.

It was never published as a paper, but what they did here was they took Pictures of 6 cats that were nucleated, so they had the histological diagnosis for iris melanoma in 2 of the 6s, sorry, melanosis for 2 cats and melanoma in 4 cats. And they sent out pictures and clinical data of the 6 CAs to 100 ACVO diplomats, meaning 100 board certified specialists in the United States, asking them what do you think these are? Is it melanosis or melanoma?

They got back replies from 78 diplomats. OK. Now again, if we were in classroom, I'd ask you how many of these 78 diplomats do you think got all 6 correct?

And the answer is shocking. Only 22 of 78 people looked and correctly identified the diagnosis at all 6 pictures. And again, I'm talking about boarded specialists, full-time ophthalmologists.

Look at the numbers, they couldn't tell . Whether it was melanoma or melanosis and sadly enough, we can't. I remember I had an old pathology teacher who said, gosh, you can only make a histopathological diagnosis using histopathology, and he's so damn right, you know, and I think this, the results of this study here, demonstrated, I cannot look at this eye and say for sure whether it's melanoma or melanosis.

So what can we do? Well, one option is maybe do aqueous synthesis, go with the needle through the limbus here and aspirate a sample of aquitumor. Cyto spin the cells and look at them.

And in fact, there are a couple of studies looking at this technique for the workup of dogs and cats with UVIT. So it's not just trying to work, determine whether or not it's a malignant tumour, it's a technique, diagnostic technique that's used in the workup of UVIT cases and as you can see here in this study from England, Looking at almost 100 dogs and cats with UVI, really the only disease that yielded a high rate of diagnosis using this technique was lymphoma. Another study from UC Davis looking at 22 dogs and cats, and again, they're saying that aussumer cytology pre permitted diagnosis of muplasia in dogs and generally not helpful in cats.

So, Yeah, we could theoretically take these cells. It's not very helpful in UVITs, may be helpful in neoplasia. Technically, what we do is we anaesthetize the patient.

We go in with a 25 gauge needle at the limbis as you saw in the previous sample picture, you use a syringe to Withdraw a small volume and then if you've got site to spin, then the best thing would do is use site to spin in order to prepare your slide cause the cells can disintegrate really very, very quickly. Even if you don't have a site to spin, use your centrifuge. For 5 to 10 minutes at a slow speed so it's not to destroy the cells, get the sediment and then make a smear and hopefully you can reach a cytological diagnosis.

But other than that, really, we have all we can offer the owners of these patients is to monitor them. So if we're seeing small focal lesions that are not progressing and not causing secondary glaucoma or secondary UVITs, then we monitor them or if they are very localised, we can Refer them to surgery, we can use cryotherapy, laser or local excision, especially in dogs where we don't have the diffuse melanoma that characterises cats. Some of these may be amenable to surgery.

So we monitored these patients and especially in cats, eventually we have to nucleate them cause we are afraid that the tumour or the lesion, I should say, is being transformed from melanocytoma to melanoma. Indications for that would be secondary glaucoma, secondary hyfema or uveitis. If we see a mass infiltrating the iridocorneal angle, it says refer for gonuoscopy, you'd need to refer a dog for gonuoscopy.

In cats, you can actually look at them from the side and see the irido corneal angle and see whether a mass is infiltrating the angle. Changes in the shape or the motility of the pupil as you're seeing here and an increase in the number of size of the masses or whether they are elevated. All of these should ring alarm bells and tell you that yes, this is now turning into malignant melanoma and you should nucleate cause if you don't nucleate, as I said, these tumours carry a very bad prognosis.

Oops. Excuse me. As I've said, adenoma, adenocarcinoma is the second most common primary tumour of the UVA and it's more common in dogs than in cats.

Adenocarcinoma is more malignant of the two and the treatment is similar to what I We have just outlined for melanoma. We monitor the patient and we nucleate when there is evidence for progression, when we see the mass growing, when we see secondary UVIs, when we see A secondary glaucoma, etc. Or maybe if it's a world circumcised tumour, you may refer them to a specialist who could try and excise these well-defined tumours.

The third primary tumour that I want to discuss is intraocular sarcoma. It's a tumour that we are seeing only in cats. As you know, sarcomas are very, very malignant.

In this case, we don't just accelerate them, we don't just nucleate them, sorry, we accentuate them, meaning we remove the eye and all of the orbital tissues. Fat and the muscles and the optic nerve and the periosteum, we really clean up the orbit to the best of our ability, but often that's not enough, and many of them die within a few months cause yes, it's a very ugly and a very invasive tumour which spreads into the orbit to the brain and other tissues. What can trigger intraocular sarcoma in cats?

Well, they often occur following penetrating cat claw injury. So if two cats get in a fight and the claw of one of them penetrates the cornea and the Lens capsule of the other cat that may trigger sarcoma. Here is a very nice review of the disease, from Juline Journal of feline medicine and Surgery in 2019, talking about the causes and treatment of These tumours and when I say treatment in these cats that present with cat claw injury that involves the lens, often the best treatment would be immediate cataract surgery in order to remove the lens because studies show us that.

The sarcoma actually arise from transformation of the lens epithelium, OK. So the cat club penetrated the lens, triggers a transformation of the lens epithelium into intraocular sarcoma and therefore this Injured lands must be removed as soon as possible in cats. Dogs, we also remove them, but we do it for a different reason.

We, dogs don't get intraocular sarcoma as I said, but we are afraid of septic lens, septic septic implantation syndrome or lens induced sitis. So yes, facal emulsification surgery may be the best option for cat claw injury both in dogs and in cats. The fact that intraocular injury may trigger sarcoma has implications for one more aspect of veterinary ophthalmology and that is intraocular gentamicin injections.

You all know probably that intraocular gentamicin injections are sometimes used to treat eyes with end-stage glaucoma, end-stage glaucoma, meaning that the eye is blind and painful. We are unable to control glaucoma medically. The owners refuse to nucleate and then in these cases, we sometimes offer, offer intraocular gentamicin injections.

Yes, I offer them in dogs. Yes, I could offer them in elderly cats, 1718, 19 year old cat with glaucoma. I don't want to take the cat into Surgery which involves general anaesthesia, maybe be a problem in such an elderly cat.

I'm happy to offer gentamycin injection because it's an 18 year old cat. It does take the sarcoma 23, or even up to 5 years to develop. So I'm not afraid that I will kill this patient with sarcoma.

However, with young cats, I am not offering this treatment modality. Here you can see a study from the University of Madison, Wisconsin. 8 cases of gentamicin, intraocular gentamicin injection, 5 of them resulted in intraocular sarcoma.

So be careful of offering this option in young cats. And one slide devoted to secondary tumours of the UVA, as I said, the most common secondary tumour is lymphoma, and you should suspect lymphoma whenever you see a white pink mass in the interior chamber or on the iris, as you can see here, the distorted pupil is another indication that yes, this iris is completely infiltrated by lymphoma frequently. They'll have present with UVI, secondary UVis, secondary glaucoma, and all the associated signs, edoema, flare chorea retinitis.

So again, I remind you to please, please, please consider neoplasia in any case of an elderly patient presenting with unilateral uveitis, un unilateral glaucoma or unilateral hyema. We see intraocular lymphoma in both dogs and cats, but in cats, they are obviously associated with FELV or FIV infection. And if there is ocular involvement, as you can see the life.

Expectancy is dramatically reduced. We can try treating the systemic disease with chemotherapy and we should treat the eye for the secondary uVis, secondary glaucoma, or a nucleate. Here is another mass, and again, I urge you to pause your recording, take a look at this and think of what it may be.

Is it a tumour or not? And if you're back, I hope most of you came up with the answer that this is a cyst. This is not a tumour, it's a uveal cyst.

I know it's a cyst because of a few things here in the picture. Number one, you can see that it has very well defined borders, sharp borders. It's not the diffused tumours that I've shown in previous pictures.

2, it is semi-transparent. I can see the typical reflection here through this cyst. And as you can see in this picture, often it is really floating in the eye, the dog or the cat shake their heads and you see the cyst moving around.

However, I do mention it as a differential for uVL tumours cause they can be confused with uVL tumours. Here is a study again from the University of Madison, Wisconsin in the United States where they have a big histopathology lab, which is why we're seeing all these Histopathology studies originating at the university, they look at 14 cases, cat eyes that were a nucleated due to suspected neoplasia but turned out to be iridociliary sis, so 14 nucleated cat eyes, 9 of the 14 were actually nucleated after they were seen by a board certified specialist and in 8. Of the 14, the clinician considered melanoma as the only suspected diagnosis, but in fact, all eyes were free neoplasia.

They had just cysts, OK? So very unpleasant situation where you tell the owners, gosh, this is melanoma. Doctor Rre said that we must nucleate as soon as possible and then it comes back as a cyst and it shouldn't have been nucleated.

So what are uveal cysts? Well, a cyst is a cyst. It's like a balloon that originates from the pigment epithelium of the iris or the ciliary body.

That's why it's pigmented. So arising from these tissues here and as you can see, these tissues give birth to. Single or multiple cysts that may be in a one eye or in both.

Sometimes they are congenital, sometimes they appear in adults, and it's another enigmatic disease, we're really not sure why they come or Go, I shouldn't say go because they don't go. Why they appear. Most are spontaneous, sometimes post-inflammatory, sometimes post-traumatic, but this is what they look like histologically and here is what they look like clinically.

So, We are talking about well-defined cystic structures that may be black, brown or varying size and shape, but as you can see in both of these pictures, sometimes you can see them transparent. They're often free-floating in the interior chamber, but sometimes may be attached to the posterior uvea cause as you can see they really originate in the posterior uvea behind the iris. So sometimes they may become visible only if you dilate the pupil or if you ultrasound the eye.

And as I said, trans illumination is a very important technique cause that's the one that will allow you to determine whether or not they are transparent. And here is another series of pictures both in cats on the left and dogs in the right, and yeah, look at it. Cats, I guess you could understand the reasons for those 14 eyes that were nucleated cause clinicians, including specialists thought it was a melanoma.

You see this huge bulging structures, melanocytic structures come picking out from behind the iris. Yeah, you could understand why some people may be mistaken, but again, look at the sharp, well demarcated borders and use your thing of transluminator to try and trans-illuminate them. Sometimes they're so heavily pigmented that they will not transluminate, but sometimes you can see clearly through them and that will Tell you they are a cyst.

Here in this histological picture and in this scanning electron microscopy picture, you can see the cysts actually attached to the posterior iris. Here, the white arrows are pointing at cysts filled with blood, which is an important clinical entity. I'll come back to in in a couple of slides.

So we see these cysts in many pictures. We see them in dogs, horses, and cats, as I've just seen, we see them also in exotic species. Here is a paper that he was truly published a couple of years ago about multiple cysts in an alligator in the cayman actually that I saw in Brazil, you can see how the entire posterior segment is just, and the interior segment is full of these cystic structures.

Here is a picture from, by a colleague from Texas looking, showing us uvial cysts in a snake highlighted against the background of this cataract. So what are the potential clinical implications of these cysts other than the possibility that they could be confused with melanoma, in which case you'd make a wrong decision to nucleate the patient. Well, if You did if you're having to fuse them with melanoma, if you correctly identify them as cysts, then often they are clinically insignificant and I tell the owners, jeez, it's just a beautiful but clinically insignificant finding.

However, sometimes, They can interfere with vision. Take this dog for example, if you've got, especially if you've got so many cysts, practically the entire eyes filled up with cysts, obviously it interferes with vision. It may affect pupil function.

Again, if I go back a couple of slides, oops, you can see how these huge cysts will affect the pupil function. They'll interfere with aqueous dynamics if the entire interior chamber is filled up with cysts that will interfere with drainage of aqueous through the angle. If they're in the back of the eye, behind the iris, they may push the iris forward and that could also interfere with aqueous dynamics and They may adhere to the interior lens capsule or the posterior, anterior, sorry, posterior inner aspect of the cornea, especially when they're deflated and then they cause a lens or corneal opacity.

So what can we do about them? Well, here is another beautiful picture of a cyst using a slit lamp. So you can see one slit on the cornea and the second inner slit on the iris and here it is climbing over a cyst and you can see that the cyst is in fact transparent.

So, unless you have the complications that I mentioned earlier, numerous cysts affecting vision, pupil function, or aqueous dynamics, we do nothing. However, if they do interfere with any of those functions, then you need to remove them or to deflate them and we can do that either when we using our accal multiplication. We can use a laser to really shoot them, sort of pop them like a balloon, like you throw darts in the balloon, you'd use a laser to shoot the cyst and deflate it or maybe a needle going with a needle into the eye to deflate the cyst or to aspirate it.

And here are a few. Articles about it. So the picture that I showed you earlier of a colleague from Texas with the Ireist, With the Irishist In a snake, it was treated with fake modification because it also had cataracts.

Here is a report of laser using to pop, the cysts in dogs, cats, and horses. And here is a picture from our clinic. I think I have to get rid of my laser for this to run, .

Showing how we would treat them. Yeah, with a needle, so you can see that this huge cyst is occluding the pupil, which is why we decided to treat it. Go in with a needle at the limbus.

This is obviously full and fully anaesthetized dog. Go in, go in, pop into the cyst and now you aspirate and as we aspirate, you can start seeing more and more of the pupil. Here.

Now you can see more and more of the pupil. Once we've totally deflated it, we can leave it there cause it's like a deflated balloon or if we wish, we can make a small incision in the limbus, going with fine forceps and remove the deflated balloon. So, So, going in with the forceps to remove the deflated balloon may require a specialist, but just deflation with a needle is maybe something you could do in your clinic, because actually this talk, does involve several indications for going with a needle into the interior chamber.

I showed you earlier that we can use this procedure for tapping the interior chamber, aqueoussynthesis. In order to take a psychological sample from the consumer. If you saw my earlier talk about UVITs, then you know that we sometimes use this procedure in order to inject tissue plasminggan activator into the interior chamber, and here is a third indication to deflate intraocular cyst, actually, I should.

Mention a 4th 1, and that is emergency lowering of intraocular pressure in cases of acute glaucoma. Just a few weeks ago, I visited a friend of mine, a veterinarian, to help with an acute glaucoma case. My friend didn't have Manitol, which would be my drug of choice, for acute, immediate emergency lowering.

Of acute intraocular pressure spike. So I just went in with the needle at the limbus, didn't even attach a syringe to the needle, just let a few drops of aqueous drip out of the needle. So you could do it, it doesn't require a specialist, but I hardly recommend that you, practise on a few cadavers before you do that.

As I said, these cysts are mostly benign, but there is one exception, and that is the golden retriever and the Labrador retriever that have a very nasty disease called golden retriever uveitis, the hallmark of which is lots of pigment in the interior chamber. The pigment disperses in the interior. Chamber, it clogs the corneal angle and with the UVI deteriorates into secondary glaucoma.

You can see that in this study of 75 golden retriever dogs, the overall prognosis is guarded 46% of the eyes became blind due to secondary glaucoma. Why do I mention it? Because you can see the cysts were common in histopathology in advanced glaucoma eyes.

OK. So this is, uveal cysts are really a predisposing factor to this disease in golden retrievers and Labrador retrievers. Some of them are full of pigments, some of them are full of blood.

I showed you earlier a picture of a cyst full of blood. And yes, they should be. And when they're diagnosed in Labrador and golden retrievers, they are definitely not incidental.

This could be a predisposing factor to a very nasty disease and you should probably refer it to a specialist. Moving on to our next disease. Again, I urge you to pause the recording and contemplate whether this cat is normal and if it's not normal, which is the normal eye, the left eye or the blue eye, and if you are back, I hope that you came back with the answer that both of these eyes are normal.

The only difference here being that one eye. Oh, sorry, I should get my laser back on. Excuse me for one second.

I think it makes it easier to see the presentation. There we go. So one eye is pigmented, you can see a pigmented iris and a nice bitter reflection and in the albinotic eye characterised by the blue iris, we see a red fundoscopic reflection.

People often owners, sometimes veterinarians will Associated with haemorrhage, but in fact, this is not haemorrhage. This is the normal appearance of an albinotic eye, just like in the days before cell phones came along, we take pictures with our cameras and if you take a picture of a blonde person with blue irises, then you'd see their pupils light lit up in red. And the reason for that is the amount of pigmentation in the RPE in the retinal pigment epithelium.

Which is a single layer of epithelium that is located between the choroid down here and the retina up here and the pigmentation of the rein pigment epithelium gives the dark. Of the non-tepitum in normally pigmented eyes in patients with a dark iris and a dark coat. Again, we are seeing a normally pigmented cat with a green teituum actually.

This is a dog picture, I apologise, and a dark non-tepitum. However, in an albinotic or a non or a subalbinotic eye, the RPE is not pigmented or very sparsely pigmented. Again, compare the amount of pigmentation here to the amount of pigmentation in this layer here and if the RPE is non-pigmented, then you can see that we really don't have a dark nontyppi in Instead, in the non-tapital area, we see the red reflection of the choroid, which explains the red reflection in the left eye of this cat.

It's subalbinotic. I know it because of the blue iris and that means also that there is less pigment in the RPE and the reflection from the choroid gives us this red reflection and again, I refer you to a talk. That I gave earlier and you can find it in the archives about doing a fundoscopic examination and explaining all the various normal variations that you can see in your funduscopic examination.

One last disease I want to discuss is what you are seeing here and yet again, because we are not in a classroom together, I urge you to stop the recording for a minute and consider why is this dog blind. Is it blind because of a tumour, an autoimmune disease, toxicity, or Leishmannia? And if you are back, I hope you gave the answer B, this dog is blind due to an autoimmune disease called UV uveal dermatological syndrome, sometimes seen in cats and horses, but most often in dogs.

Uveal dermatological syndrome, meaning it involves both the eyes and the skin and I refer you to A recent review paper that came out of UC Davis, University of California Davis looking at 50 dogs with uo dermatological syndrome. This is the most recent and comprehensive review of the disease. The disease is seen in the Arctic breeds or the northern breeds, so most often in the Akita, as you can see here, but also in the Siberian huskies, Samoyed, Alaskan Malamud.

So in fact, this was one hint for you that you can't see the eyes to tell you why the dog is blind, but you can see the breed. So this is one hint here. The disease is for some reason most, more common in male and a middle aged disease.

As I said, we are talking about an autoimmune disease and The target tissue is something you could see in the previous picture and also in this picture, the target tissue is really the pigmented tissue, which is why I am seeing the pigmentation in the eyelids and in the nose. So yes, we are talking about an autoimmune reaction against melanocytes and there are antigens. Sometimes you'd hear the People call the Uo dermatological syndrome VKH.

VKH, excuse me, is actually the name of the disease in humans, as humans suffer from a similar disease whereby we have an autoimmune inflammation against melanocytes. Unfortunately, in humans, it's a nasty disease cause it also causes meningitis. Thankfully, our patients don't get meningitis, but they do present.

Often with ocular signs and 100% of them will present with skin lesions. So what are the ocular signs? Well, we have an autoimmune disease directed against pigment.

Where do we find pigment in the eye? Well, we find it in the interior uvea, in the iris. We just saw pictures of lots of pigment in the iris and the ciliary body.

All those cysts that I showed you originated in the pigmented epithidium of the. Iris and the ciliary body and we find it in the posterior I just showed you the RPE full of pigment in the non-topital area. So those are two target tissues as well as the eyelids that will become depigmented.

And just like any autoimmune inflammation, it's a very nasty inflammation in the study from UC Davis, half the dogs were blind at presentation because the UVIis caused secondary glaucoma. Looking at the skin lesions, again, the disease attacks the pigmented tissues. So look for the pigmentation in the oral cavity, in the foot pads, in the lips, in the scrotum, and in the claws.

So you're looking for loukoderma, lootria are the most common skin lesions. You can see lots of Erosions and ulcerations and repeia and in the foot pads, you'd see hyperkeratosis and loss of claws. So really a very, very nasty dermatological disease, but as you can see, this dog also has UVI, OK.

So really a prevalence, as I said, ocular disease will occur in 85% of them. The skin disease occurs in 100% of the patients, especially in the face, in the nose, in the eyelids, as you can see here, look for the pigmentation in the lips and examine other pigmented tissues and here are a few pictures showing you the dermatological lesions that should raise your index of suspicion that you are seeing uvial dermatological syndrome. Back to the ophthalmic signs, as I said, you will see eyelid depigmentation.

And you will see uveitis, both anterior uveitis that we are seeing here with corneal edoema, lots of flare, corneal vascularization, typical red eye, and all of these indicate that not only do we have UVIis, we are also having secondary glaucoma. Pataggnomonic sign for the disease is the changes that we see in the non-tepitium. They're not so obvious here, but you can see these whitish shallows, here they are more obvious.

These are focal areas of depigmentation where the immune system attacks the Melanin in the retinal pigment epithelium causing these focal lesions that you are seeing here and here. So, if you suspect uo dermatological syndrome and you would say actually, I would forgive you if you say that some other dermatological diseases may have similar presentation, lupus, etc. So you really need to confirm your diagnosis histopathologically.

And if you take and when I'm saying histopathologically, I'm talking about a dermal punch biopsy from involved areas from deep pigmented areas and this is the report you'd get from the pathologist who would see subdermal infiltrate, lots of macrophages, lots of lymphocytes, lots of inflammatory cells. You can see them here in the deep dermis. In the arrowheads, and you can see the arrows pointing at these granular dust like microphages that are really melanosomes in the macrophages.

Once you have a diagnosis, obviously, we treat the disease and just like any autoimmune disease, we throw all of the anti-inflammatory drugs that we can at the dog. We use steroids, be they oral, topical, or subconjunctival. We use other.

Anti-inflammatory drugs such as cyclosporin, tacrolimus, azathalprine, cyclopentolate, whatever is available in your country. And even though the disease has both ocular and dermatological manifestations, the treatment is really based on the severity of the ocular signs, OK. If the uveitis is very mild, maybe you would maintain the patient.

Just on topical drugs, but whenever you have a flare-up of the ocular signs flare-up of uveitis, then you would switch to oral or subconjunctive treatment and more aggressive drugs. Often you'll get a remission, but hey, it's an autoimmune disease, so you, lots of relapses and as I said, half of the dogs in the most recent study have become blind by the disease. So this ends my review of Uveal diseases that you should consider other than uveitis as I said, please think of the tumours.

Please consider cysts as a differential that may look like a tumour but is not a tumour. Remember that albinotic dogs may present like this with a red fundus reflection and remember the workup and treatment of your uvealder mythological syndrome. Because this is a recorded lecture, I can't see you and therefore, I brought my own applause.

Thank you very much for your attention and I will see you again in the summer in May with my first lecture on equine ophthalmology. Thank you very much and goodbye.