Hello, everyone, and welcome to my talk about the red eye. I call this talk 50 Shades of Red in reference to the book 50 Shades of Grey. I admit I haven't read the book, but I like the title cause I assume, even though I haven't read it.
That, it means that not all greys are the same, not all grey colours are the same. They are of different shades, and I think the same is true of the red eye. Red eye is a very common presentation, .
In our patients, but not all red eyes are the same. Here are two examples, 2 red eyes, but they are definitely suffering from different diseases and hopefully by the end of the talk today you'll know how to diagnose and treat them. As I said, red eye is a very common presentation in veterinary medicine, veterinary ophthalmology, simply because of the rich blood supply of the eye.
You can see here the numerous blood vessels supplying both the eyelids and the conjunctiva and the intraocular structures, and here you can see them in this cast. Yes, it is richly vascularized. So there are a number of diseases that can present with red eye.
Here are 3 of them, and I urge you to I hit the pause button for a second, look at these 3 pictures and see if you can determine what each of these eyes is suffering from. So you press pause, I'll stop for a minute. And if you are back, we can go to the answers.
So this eye is suffering from glaucoma, this one has uveitis, and this one has conjunctivitis, and these are indeed the three leading different. For a red eye, but they are not the only ones. Red eye may also be a presentation in cases of deep keatitis, superficial keatitis, and orbital disease that you are seeing here.
So really we're talking about 6 diseases here that I've just mentioned and the question is how do I know which is which? And in order to reach a diagnosis of a red eye, I have put together this checklist for you. Here is a list of all the things that you must check in order to determine what caused The red eye and obviously we will go through them one by one, starting with the depth of the blood vessels, which blood vessels are congested causing the appearance of red eye.
So red eye may be due to congestion of superficial vessels or deep vessels. Superficial vessel congestion is usually associated with a superficial disease or a chronic disease. So we are usually talking about conjunctivitis or superficial keatitis, which is what we are seeing here with these blood vessels invading the cornea.
Deep vessels are associated with a deep disease, and we'll see some examples later on, or an acute disease and the leading differentials are uveitis, glaucoma, deep keatitis, and orbital disease. And again, here we have an example of an eye with kerato uveitis, so it incorporates the first and the 3rd diagnosis. But the question you're obviously asking yourself, yeah, this is a great superficial deep, but how do I know whether I'm looking at deep or superficial vessels?
Well, here is the answer. Superficial vessels usually originate in the conjunctiva, but they invade the cornea and they are individually. Identifiable.
You can see here, each of the vessels that's invading the cornea can actually be traced back to its origins in the conjunctiva, so they are extension of conjunctival vessels and you can identify them individually. Also, if you take a close look, you can see that they branch like branches of a tree or the roots of a tree. They often present with commosis or edoema of the conjunctiva, which is what we are seeing here.
They are of smaller diameter than the vessels will be discussing in the next slide, and they are mobile in the sense that I can put a drop of total anaesthetic on this eye, take forceps or cotton swab. And move them, move the conjunctiva, and you'll see that the vessels move with it because they are conjunctival vessels, as we said earlier, they are of conjunctival origin, so I can move the conjunctiva and I'll see these vessels moving. And if you're still uncertain, take a drop of epinephrine, place it in the eye, and they will blanch immediately.
So all these are indications that we are looking at superficial vessels, which are, as I said, are associated with superficial or chronic disease, namely conjunctivitis or superficial caratitis. Deep vessels can be divided into two or out of two origins. We are talking about epicleral vessels which we are seeing in this diagram here on the surface of the eye on the underneath the conjunctiva, as the name implies they are.
Between the sclera and the conjunctiva, or they may be anterior ciliary vessels. And a congestion of ciliary vessels of intraocular vessels. The episcleral vessels that you are seeing here are large diameter vessels and you are seeing here very large diameter vessels, as opposed to the smaller diameter of the vessels that we've seen here.
Here we can see how this is a small diameter conjunctival vessels, and this is a large diameter episcleral vessel again, small diameter conjunctival, large diameter epicleral. I think you can tell the difference in their diameter and the congestion of episcleral vessels is typically associated with glaucoma. In cases of uveitis, uveitis is obviously inflammation of the iris and the ciliary body.
That's when we have congestion of the interior ciliary vessels that you are seeing here. They are intraocular vessels, so you can't see individual vessels as you would in the case of conjunctivitis or keatitis. Instead, you would see sort of a diffuse red flush that you are seeing here.
And if they invade the cornea, it will have a paintbrush appearance or toothbrush appearance. You can't see the individual blood vessels just like you can't see the individual blood vessel, sorry, the Individual bristles in a paintbrush or toothbrush, OK, so unlike The cases of conjunctivitis or epistle congestion where you could identify individual vessels, here you can't really identify the individual blood vessels. It's more of a diffuse appearance because we're talking about congestion of vessels inside the eye.
Congestion of blood vessel of deep vessels is, rarely associated with chemosis. They rarely branch and because they are deep vessels, they are immobile. Put a drop of anaesthetic in this eye or in this eye, take your swab or 4.
The blood vessels will not move you are moving the conjunctiva, but these blood vessels are beneath the conjunctiva and they'll remain immobile. And if you put a drop of epinephrine, yes, eventually they will blanch, but it will take much longer than the blanching that you see if you are, see if you're faced with congestion of superficial vessels. So this is the appearance of deep blood vessels and here they are side by side.
So again, conjunctivitis, you are seeing individual blood vessels that are branching like the roots of a tree, OK? And you can see that they are also torches. Episcleral vessels associated with glaucoma.
You can see the much larger diameter, compare this one to this one, compare this one to this one. They don't branch as you can see, and they are not as. Tortuous.
OK. So this is a good side by side comparison and again these ones will be mobile, these ones will not be mobile. These ones will blanch immediately with epinephrine.
These ones will take a couple of minutes to blanch with epinephrine. So just by looking at the blood vessels and Identifying whether they are superficial or whether they are deep, we can already get an indication whether we are looking at glaucoma, UVitis, or deep keatitis, which are associated, as I said, with congestion deep vessels or whether we are looking at conjunctivitis or dry eye superficial keraitis associated with congestion of the superficial blood vessels. Next on our list is the Schermer tear test used to diagnose dry eye, conjunctivitis and superficial keatitis.
And as it says here, please, in every patient that presents with red eye, and it doesn't matter whether it's deep vessels or superficial vessels, if you're uncertain, please. Measure tear production before the Schmer tear test. It takes just 60 seconds or 120 seconds for both eyes, and it gives you a diagnosis.
And you may be surprised to see how many cases of dry eye you missed simply because you haven't performed the Shimmer tear test. So, it's very diagnostic. It takes only 60 seconds.
And another thing I like about it is that it's very visual and you can share the results with the owners. You know, sometimes, you do an ultrasound or you do an ECG and you try to show the owners here, you see this ultrasound image, your dog is suffering from, This or that, or you see this ECG trace, your dog has this or that. They're looking at the screen, but they don't really understand what they're seeing.
Shearer, it is so easy. You show them the strip and you say your dog was supposed to have more than 15 millimetres of wetting within a minute, but it only has 4. Your cat.
It was supposed to have 9, but it only has 4. Your, pet has dry eye. So it's a very visual test.
The owners can immediately understand what you're talking about. They can understand why they're now going to spend lots of money on tacrolimus or cyclosporin. And when they come for recheck, you can easily show with them the improvement of the treatment that you have prescribed.
So, just by doing a Schmert test, you can definitely reach a diagnosis and confirm a diagnosis of a dry eye. The next thing you wanna look at is the size of the pupil and is it constricting? Is there a PLR or not?
Uveitis is associated with meiosis because of spasms of the ciliary body and in fact, because the pupil is meiotic, as you can see in the left eye of this dog, it may have minimal direct PLR cause it's already so constricted, it can hardly constrict any further. There will be, however, an indirect PLR when you stimulate this, this pupil. Hopefully will constrict.
However, in U VITs. Please note that the pupil may be distorted. As you can see in this picture, it's distorted because the iris is adhered to the anterior lens capsule, what we call, posterior sinicia, and that is another indication that this animal has uveitis.
So yes, meiosis or distorted pupil are two indications that the red eye, which you're seeing here is due to. Uveitis. However, note that a pupil may also be meiotic in acute keraitis or corneal ulceration, and that's because every sensory stimulation of the trigeminal nerve in the cornea, .
Stimulates the ciliary body through a neuronal feedback mechanism. So meiosis may may also be associated with keraitis which or corneal ulceration which indeed causes secondary uveitis. On the other hand, glaucoma patients will present with a dilated pupil.
Often a fixed dilated pupil. So this is looking at the pupil and seeing whether it's myotic or metriatic can definitely help you differentiate between Uatis and glaucoma. Remember that a fixed dilated pupil may also be associated with an orbital disease because retrobar disease may involve the optic nerve.
Conjunctivitis, superficial keratiti, KCS present with a normal pupil. So just looking at the size of the pupil and whether it's responsive or not can give you an indication of which of the diseases we are looking at. Are we looking at glaucoma, fixed dilated pupil?
Are we looking at UVITs? Myotic pupil that can hardly constrict any further or are we looking at conjunctivitis which is associated with a normal pupil. Next on our checklist is aquiz flair, loss of transparency of the aquiz humour.
Aquez flair is a Very, very important clinical sign of UVI. It tells us that the aqueous tumour, which is normally transparent, is filled up with inflammatory material, white blood cells, protein, platelets due to uveitis. And the analogy that I give for detection of aqueous flair is think of yourself sitting in, going to a movie, you're sitting in a cinema that Cinema is dark just before the movie starts, and then the projector at the back of the room comes on, bright beam of light, and all of a sudden you see all these dust particles that are floating in the air.
They were there also when the room was dark. You just didn't see them, but they are highlighted by the movie projector. This is exactly what we are seeing in an eye with UVI.
On the left here, we have a normal eye with no inflammation. We illuminate the eye with a bright beam of light using our slit lamp. That's why you're seeing that it's a narrow beam of light, and I'm seeing one beam of light here on the cornea, a bit on the eyelid margin, and I'm seeing the inner beam of light here illuminating the lens and the iris.
In between the cornea and the lens and the iris is the interior chamber full of aquiumor and you can see it is dark. It is dark cause it's completely transparent. There are no particles in it.
On the other hand, here, we have an inflamed eye, an eye with UVI. Again, we illuminate it with our slit lamp, we see the First beam of light on the cornea and on the 3rd eyelid and on the eyelid, we see the inner beam of light illuminating the. Lns and the iris and in between them, the aque humour which was previously dark, is now lit up.
It is lit up because the beam of light . Is illuminating all of the inflammatory material. It is illuminating.
It is reflected by the blood cells and the protein and the fibrine just like the dust particles in the movie house. . If you don't have a slit lamp, which is a bit of an expensive instrument, don't worry.
You can use or you can see the same effect using your direct phthalmoscope, turn it to the smallest aperture, . Look at the Aquisumer and you'll be able to see whether it is transparent or whether it is not transparent. Again, just like the movie house and if you don't like the analogy of the movie house, and the projector illuminating dust particles.
Here is another analogy that I'm sure you'll, remember. I gave this lecture once in China and we're talking about UVITs and after the lecture, we went, to have dinner and obviously we had some beer and then the guy sitting next to me says, here is your aquis flair. Filtered beer, unfiltered beer, OK?
Beer without particles, transparent, unfiltered beer, you can see all of the particles floating in the beer, so I'm sure that this will help you remember what a quiz flare is all about. The inflammatory particles that are floating in the interior chamber in the aqueous humour as part of the inflammation, may actually Condense, they may form a hypopion, clot of white blood cells. You can see also some red blood cells here.
The fibrine there, which is floating in the interior chamber may also form a clot again with some blood elements. Obviously you can get leakage of blood from the Inflamed blood from the blood vessels of the inflamed iris ancillary body and the inflammatory material may also sink on the inner. Part of the cornea on the endothelial posterior cornea, which is what we're seeing here, we call it keatic precipitates.
You take a close look at the cornea and it's as if someone has thrown mud against the cornea, someone inside the eye is throwing mud. And it adhered to the inner cornea and which is also what you're seeing here, or alternatively it can adhere to the interior lens capsule, which is what we are seeing here, so carattic and lens precipitates. So Aquis flair.
Fibrin in the interior chamber, high femur in the interior chamber, inflammatory material deposited on the lens or on the inner cornea, all of that would tell you that you are looking at an eye with UBI. Next on our checklist, tometry, measurement of intraocular pressure to determine whether or not the eye is suffering from glaucoma or from uveitis. Most, animals would have a normal pressure range of 15 to 25 millimetres of mercury.
Pressure increases in glaucoma due to drainage problems, and less aque is exiting the eye, thereby increasing intraocular pressure. Pressure is lower in UVITs due to increase in the unconventional outflow of aqueous from the eye, and if you don't know what I mean by unconventional outflow, I urge you to go to the alphabet, archives and see, my lecture about glaucoma. And finally, pressure is normal in conjunctivitis.
So again, a very simple test that will help you determine which of the three leading red-eye, differentials you're looking at. Are you looking at glaucoma, UVitis or conjunctivitis, elevated pressure, lower pressure, or normal pressure. When measuring pressure, please measure it in both eyes because significant differences in pressure between eyes are suspicious.
I just said that the normal pressure is 15 to 25, but if you have pressure of 12 in one eye and 24 in the other eye, then a difference of 100% is obviously very worrying. It shouldn't happen and you need to ask yourself why. Another thing to keep in the back of your mind is that normal to high pressure in uveitis is suspicious.
I just said that in uveitis, pressure decreases due to increasing the unconventional drainage of aqueous from the eye. In I with uveitis, we typically measure a pressure of 456 mill millimetres of mercury. If you're presented with an eye that has UVIs based on the presence of aqueous flare, etc.
Etc. Yet the pressure is 22, you should be concerned. 22 is theoretically normal.
I said 15 to 25 is normal, but 22. It is not normal for an eye with UVITs, and you should be asking yourself whether the hypertension, the lower pressure caused by UVITs, is in fact masking the elevated IOP associated with glaucoma. When measuring pressure, please make sure that the assistant is not pressing on the jugular veins cause aqueous drains into venous circulation and pressing on the jugular veins does elevate pressure, in people wearing neckties is a risk factor for glaucoma and please use an instrument, not your fingers, to measure pressure.
If you can afford one of the modern electronic. Tonometers that I, I highly recommended the tonopen or the rebound tonometer Tonovet or tonovet plus, all of them take very accurate readings. They take several readings and display the mean IOP with a statistical error.
They are very user friendly and are well tolerated by the animals and. However, if you can't afford this, you should at least buy a shield indentation toometer. It's an older instrument.
It's a mechanical instrument. There is a bigger learning curve on how to use it. Animals don't like it as much.
The head has to be held. Particularly as you can see in this picture, the readings need to be converted, etc. Etc.
But with practise, it will give you a good indication of IOP. This is an instrument that was used in humans, for many, many years until the more modern therometers came out. So just by measuring intraocular pressure, you can tell whether you're looking at glaucoma or whether you are looking at UVI test.
Next on my checklist, we're getting towards the end is retropulsion, which would help us determine whether the patient is suffering from retrovular disease. Retropulsion is what we are doing here. As you can see, we are using we are applying.
Pressure on both eyes through the eyelids. I am not measuring intraocular pressure in this picture, OK? I just said that to measure intraocular pressure you need an instrument.
You can't measure intraocular pressure with your fingers. What I'm doing here is pressing. On the globe through the eyelids, and I am trying to determine whether the eye is sinking into the orbit as I press on it, or whether there is something behind the eye that's resisting that is not letting me push the eye back into the orbit, OK?
Now, I know it sounds like I'm walking a fine line. Is this an eye with elevated pressure, a tough eye that is sinking back into the orbit, or is this a normal tensive eye with normal pressure that will not sink back into the orbit, but with enough practise, you can tell the difference and also this is the reason for doing it in both eyes at the same time. You will feel that normal pressure.
In one eye as you push it back into the orbit and you feel identical pressure in the other eye that will not sink back into the orbit. Of course, another way to confirm retrobular disease is through imaging, be it CT, ultrasound, or MRI which shows you retro bulbar disease such as you're seeing in this patient with a retrovulbar tumour. So a retropulsion test or imaging of the retrovulbar space would tell you whether you are looking at an orbital disease.
And finally, in our checklist after we've done everything, fluorescent staining, to tell you whether the cornea is ulcerated or not, will help you differentiate between deep keraitis, often associated with a deep ulcer, superficial corneal disease, or plain old conjunctivitis. So this is my checklist for the red eye, but in addition to that, we also have unique signs for each of the differentials, leading differentials that I've discussed. Unique signs of conjunctivitis.
Well, conjunctive patients with conjunctivitis present with mucoid or purulent discharge. We don't see any discharge in UVIis or in glaucoma. There is involvement of the 3rd eyelid.
The 3rd eyelid is also congested and would also be red cause the 3rd eyelid is really lined by conjunctiva. So any conjunctivitis that's affecting the Palpi conjunctiva, the bulbar conjunctiva will also affect the conjunctiva of the third eyelid. So if you see a third eye, a red 3rd eyelid, it's probably a sign of conjunctivitis, but remember that it may also be elevated in or.
And maybe even red in orbital disease, we saw that here in this patient, yes, because the orbital disease disrupts the circulation in the orbit, you may get third eye involvement. Kemosis or edoema of the conjunctiva is another sign that is unique to conjunctivitis. We don't see any chemosis in uveitis.
We do not see any chemosis in glaucoma. And finally, hypertrophy of lymphatic follicles, you are seeing them here on the sorry, on the palpibral conjunctiva of the lower lid, you can see them on the outer surface of the third eyelid and most prominently, you will see them on the inner aspect of the third eyelid. So if you took it, put a drop of topical aesthetic in.
The eye, take fine forceps or cotton swab, invert the third eyelid, you can see significant hypertrophy of lymphatic follicles and again lymphatic follicles are unique for conjunctivitis. You will not hypertrophy of these follicles is not associated with Uitis or with glaucoma. Unique signs of glaucoma include talus, as you're seeing in the right eye of this dog, as the pressure increases, the eye inflates like a balloon, so obviously that is a sign that we see only in glaucoma.
And another sign that we are seeing in glaucoma is stride keratopathy as the eye stretches, as you get talus, all of the that you get stretching of the sclera and you get stretching of the cornea, and we are seeing these white lines here on the cornea. They are fractures in the cornea, just like fractures in the ground in cases of an earthquake. Really, the cornea is so stretched that you get these fracture lines.
These two signs are pathognomonic for glaucoma. . In case of strike keratopathy, it was a sign that does not recede.
So even if you have managed to bring the pressure down, fractures will not heal, so the stri. Curtopathy will tell you that this eye may have had the glaucoma attack in the past. Bufalmus is a sign that may recede, bumus is more noticeable in young patients where the sclera is more elastic and therefore it stretches more easily and if the pressure comes down, then it Easily reverts back to its original size.
In an elderly patient with less elastic sclera, the balmus is maybe not as noticeable or maybe it takes longer to become visible, and when the pressure comes down, you. Excuse me, the eye may still remain balmic because again the sclera is not so elastic and it will not revert back to its original size. Another pathognomonic sign for glaucoma is optic nerve cupping.
If we look at the fundus, we can see changes in the optic nerve associated with glaucoma. Here is a fundus of a normal dog with a healthy looking. Optic nerve head, we can see it is pink, in colour, we can see that it's triangular in shape, and we can see the blood vessels crossing the surface of the optic disc as they cross it here histologically.
If pressure is elevated, you get ischemia of the optic nerve, you get mechanical compression of the optic nerve, and that's what we are seeing here due to the compression of the optic nerve. You can see that the optic nerve really sinks back. Compare this picture to this picture and as it sinks back we can no longer see the blood vessels crossing the surface of the disc.
And the optic nervehead loses its smiling sheath. Therefore, it is more circular than triangular. It is more grey in appearance rather than pink in appearance.
So this is another classical pathognomonic unique sign of glaucoma. And finally, for our 3rd differential UVIs, it is also associated with unique signs. We spoke about a quiz flair earlier, but it has a few more classical signs.
Number one, the iris is dark and congested. As you can see in the left eye of this cat because of the increased blood flow in the iris, we can get posterior sinicia which I mentioned earlier, adhesions between the iris and the lens. That is also something that we see only in cases of UVIT.
And that's because the adhesions are, is facilitate are facilitated by the inflammatory material that is present in the interior chamber in uveitis. OK. I mentioned that in uveitis, the aqueousumer fills up with white blood cells.
It fills up with platelets, it fills up with fibrin. All of this is sticky material. And if you have a meiotic pupil in your VI, and, and the meiotic pupil means that the iris is in contact with the lens and lots of glue, lots of sticking material is floating in the interior chamber, then you'll get adhesions between the iris and the lens.
Again, something that we see only in UVI. And anterior uveitis may spread to involve the posterior uvea, the choriortinitis. So when you see a red eye with posterior segment disease such as you are seeing here, that is another unique sign of UVI because this is not something we'll see in glaucoma.
This is not something we will see in conjunctivitis. So, in addition to the checklist that we've reviewed earlier, look for the unique signs, look for the secretions and follicular hypertrophy that tells you it's conjunctivitis. Look for the bufalmus triatopathy and optic nerve cupping that tell you it's glaucoma.
Look for the congested iris, for the adhesions, for the aqueous flare, for the posterior segment disease that tell you that it is a case of uveitis. And then hopefully, you will be able to know what. Are you seeing which disease is causing the red eye in your patient?
And Once you've reached diagnosis, I want to devote a couple of words to how do we treat these diseases. Each of them is really a talk onto itself, and again, I urge you to go to the alphabet archives and listen to the talks about UVitis, glaucoma, and conjunctivitis, but take home message for the treatment of each of these diseases. UVI Please remember that bilateral uveitis is most often due to a systemic diseases, to a systemic disease.
I have a colleague at the University of California, Davis, David Maggs, who really says that UVitis is an ocular lymph adenopathy. And just like a systemic infectious disease can cause lymphadenopathy of the submandibular lymph nodes or the pre-scapular lymph nodes, it causes a lymphadenopathy in the eye. So, It is really a consequence of a systemic disease and that leads me to the second take home message.
UVitis is really a clinical sign. It is not a diagnosis, OK? Once you've determined that a patient has Uveitis again based on the myotic pupil and low IOP pres presence of aqueous flare, etc.
Etc. You haven't made a diagnosis. You've just determined that the patient has UVIS, but as I've said, in many cases, the UVIis is due to a systemic disease and therefore, if you've determined that the patient has UVIis, you must perform a systemic workup, comprehensive systemic workup, history, physical exam, .
Minimal blood work, CBC, biochemistry, and depending on what you find, continue with urinalysis and chest X-rays and molecular testing, PCR analysis, etc. Etc. You must try and reach a systemic diagnosis, number one, in order to treat the UVIT successfully, and number 2 cause if your patient has a systemic disease, you obviously wanna determine the cause.
However, Please beware that even though bilateral uveitis is often due to systemic disease, many cases of uveitis are idiopathic, and this is something that you have to tell the owners and warn the owners. You have to tell them, listen, I'm going to do this extensive workup which is going to cost you a few €100 or pounds or dollars, but be prepared that many times the The blood work will come back normal. I'll be happy for you if it's normal.
I'll be frustrated that we don't have a systemic disease to treat which makes the, prognosis of UVIis better, but in any case, we must do it cause we must know whether your pet, your dog, or your cat is suffering from a systemic disease. Here are a couple of studies just showing what or demonstrating what I've just said. A study of 55 cases of canine UVIT at Purdue University in the United States.
You can see that, many patients were suffering from infectious diseases and you can see that in, in In Purdue, in Indiana, fungal diseases are very common. If I were to do the same study, I'd probably find lots of lichia. If my colleagues in Spain would do the study, they'd probably find lots of yishmania.
It all depends on what's endemic in your area, but yes, infectious diseases are common. BKH and autoimmune disease, sometimes it can be idiopathic, but look at this. Almost 2/3 of them are idiopathic despite extensive workup in a very good vet school in the United States, no systemic diagnosis was reached, OK?
So that goes back to what I said. You must perform the workup cause you wanna know if the patient has blasto or lepto or histo or whatever, . You must do the workup.
But tell the owners, hey, there is a very good chance that all the blood work will come back normal, warn them ahead of time cause owners don't like to spend money and then hear that everything is normal. The same is true for cats. A study of 120 cats with UVITs in North Carolina State University.
Leading differentials in CAT are TOXO, FIP, FIV, and FELV. Again, cases of neoplasia, and again, as you can see, the majority of cats, they actually UVI was actually idiopathic. All of the testing in North Carolina State University was normal.
If you're doing the math in your head, you may see that the total here comes up to more than 100. I realise that it is not a typing mistake. It's because, as you know, toxoplasma will often present with FIV or FELV and that is why we have more than 100% here.
Some cases were, some cats were positive for more than one of the agents. And finally, the most important thing that you ought to remember about conjunctivitis is that conjunctivitis is really a classic case of a dog is not a big cat. A cat is not a small dog, and that's because our clinical approach to a Cat with UVI and a dog with UVI is completely different.
In a dog with UVI, the in the con conjunctive, said Uveitis, sorry, conjunctivitis. In a dog with conjunctivitis, The disease is usually secondary. We're talking about a secondary infection or secondary inflammation due to chronic irritation of the eye.
Maybe it's a bra, it's a phallic breed like a Pekinese or a shih-tzu with the exposed eyes and the lack of almus, maybe. There is, it's a case of dysychia enthusiasis irritating the cornea. Maybe there is entropion or ectropion.
Maybe there is a dry eye such as you are seeing here, evidenced by the dull flash of the camera there. It is something that is irritating the eye and because of the chronic irritation, you really get overgrowth of the normal flora of the eye and you get secondary conjunctivitis, secondary conjunctivitis. Which is why really when I am presented with a case of canine conjunctivitis.
I rarely take. So, I, I, I, I rarely collect a cultural insensitivity because I know that 95% of the time it will come back as Stylococ or streptococ. It will just be the overgrowth of the normal flora of the eye.
So instead of wasting the owner's money on culture and sensitivity, you should concentrate on identifying and treating. The primary cause. So do a comprehensive oanic exam.
Look for entropion. Look for ectropion, look for dysychia, look for tracheosis. Do the chimer tear test again, another case of dry eye, because again you can see the dull camera flash.
Identify the primary cause, treat the primary cause, and Then you can treat the residual conjunctivitis with broad spectrum antibiotics or steroids. But really the most important thing to remember about canine conjunctivitis is that if you treat it without reaching a diagnosis of the primary cause, you will not cure the disease, OK? Let's take this patient, for example, yeah, I can give it antibio topical antibiotics.
I can give it topical steroids. It will make the inflammation go away simply because I'm wetting the eye with the steroids or with the antibiotics or even with tap water. But as soon as the owner stops treatment 2 or 3 weeks down the road, the inflammation will come back because I didn't diagnose the dry eye.
I didn't treat the primary problem. OK. As opposed to feline conjunctivitis where it's a primary disease, OK.
We just said in dogs, conjunctivitis is a secondary disease in cats, it's a primary disease. There are primary pathogens of the feline conjunctiva and as I often tell my students, the three leading pathogens are herpes, herpes, and herpes with chlamydia in 4th. Most cats in the world are latent carriers of the feline herpes virus, and when the cat is exposed to stress, you will get recurring disease.
Because stress is such an important factor in the pathogenesis of herpetic conjunctivitis in cats, I often say that in mild cases, no treatment may be the best option because, you know, cats are. They don't like to be grabbed 2 or 3 times a day and have the owners put drops or oral drugs in their mouth, that may induce lots of stress. So actually sometimes treatment may.
Make things worse and you'll remember that do no harm is the first principle of treatment in our patients and therefore, sometimes in mild cases, no treatment may be the best option. In more severe cases where treatment is necessary, oralamcyclovir and Toycidofovir are very effective drugs that can be given only twice daily. There are other effective drugs out there like trifluoridine or like a doxorudine, but they have to be given 5 or 6 times daily.
Brings back the . Risk of stress, drugs that have to be given only twice daily are much safer than these other drugs. And if you heard my lecture about feline conjunctivitis, you know that in our school we use pencyclovir cream, pencyclovir.
I actually I should say Pancyclovir is the pro-drug of pencyclovir. So when you give or pencyclovir, it is converted into pencyclovir. However, in many countries, pencyclovir It is available as a cream to treat herpes in humans, so it's a dermal preparation, but we've been giving it safely in cats for many years and we are very happy in the results.
And the final thing you want to remember about treatment of conjunctivitis is that all of the drugs that I've mentioned are static. You do not kill the virus. You do not eliminate the virus.
The definition of successful treatment in cats with conjunctivitis is that the virus reverts back into a latent state and unfortunately, if the cat experiences stress, then the disease may recur. And finally, the most important thing that I want you to remember about the treatment of glaucoma is that primary glaucoma patients may present with unilateral disease. In fact, many patients with inherited primary glaucoma present with a disease in one eye, with the second eye being affected an average of 8 months later.
And therefore, when you are presented with a patient with unilateral glaucoma, please consider giving prophylactic treatment to the other eye. What do I mean by that? You've just been presented with a patient with glaucoma in the right eye.
This may be a case of primary inherited glaucoma, in which case this eye is at risk of developing glaucoma 8 months down the road, or it may be a case of secondary glaucoma. Maybe this patient has a tumour in the eye. Maybe it has a lens laxation.
So, when you see this patient, try to determine if there is evidence of this being secondary glaucoma. Is there uveitis in this eye? Is there a tumour in this eye?
Is there a lensation in this eye? All of these diseases could have caused secondary glaucoma in this eye, and it means that this eye is not at risk. But If you do not see evidence of UVI, if you do not see evidence of a tumour, if you do not see lens laxation, this suggests that this eye may be suffering from primary glaucoma, in which case you should prescribe prophylactic treatment to the left eye.
Obviously prophylactic treatment will not. Cure glaucoma. It will not prevent this left eye from developing glaucoma, but studies have shown us that it will postpone the onset of glaucoma by 2 years.
So the second eye, instead of presenting with glaucoma 8 months from now, will present with glaucoma 32 months from now, you have bought this eye another 2 years. So, this completes my checklist of red eye and how you should work up your patients. And I'm going to leave you, and, sorry, how to work up your patients and how to determine whether they're suffering from glaucoma, UVIis, deep keatitis.
Conjunctivitis, superficial keraitis, or orbital disease, and I'm going to leave you with this flow chart, put together by my friend and colleague Karen Plummer from the University of Florida, that can also guide you through your workup of a patient presenting with a red eye. As I've said, many of the diseases we've been discussing in this talk are available in the Alphabet archives and library. So if you wanna hear more about any of these diseases, I welcome you, invite you to go and listen to these lectures.
Thank you very much for your attention and goodbye.