OK. Hello, everyone, and welcome to yet another ophthalmology lecture in the webinar vet series. My name is Ron Offrey.

I'm a professor of veterinary ophthalmology at the Hebrew University of Jerusalem, Israel, and today I'll be talking to you about ophthalmic examination of your patients, what you should have, and what should you do as an ophthalmic patient walks into your clinic. As always, I won't declare that I have no financial or non-financial relationship with any product I'll be mentioning in my talk. However, by way of disclosing or shameless advertising, I should note that 4 months ago, I gave another lecture on ophthalmic examination of the fundus or ophthalmoscopy.

And when you combine today's lecture with this previous lecture, then you will be ready for my upcoming lecture January 7th when we shall be discussing blind patients. So really you wanna listen to both of these lectures, we will not be covering the fundus today because we covered it in August and If you listen to recordings rather than live broadcasts, then in fact, I suggest you listen to this ophthalmic exam lecture first, then listen to the fundoscopic exam and you'll be ready to go for the blindness lecture in January 7. And those of you who've been to my previous talk know that I have another slide of shameless advertising or disclosure in that many of the pictures I'm showing in my lectures are taken from a textbook in Veterinary ophthalmology that I've co-authored now for 3 editions together with David Max from UC Davis and Paul Miller from University of Wisconsin-Madison.

Right. So, I know that many people are apprehensive about an ophthalmic examination, and they are apprehensive for two reasons. Number one, they think, oh my gosh, it's so complicated.

It's such a small organ. How do I examine it? And really an ophthalmic examination is not complicated.

I divided into three parts. The first part is a cross examination of the patient, from a distance. We're not looking too closely at the eye, we're not touching the eye.

We're just examining the patient as a demonstrate in a minute. Then we assess the patient's vision. And then we examine the entire eye from the front to the back, from the eyelids and the conjunctiva through the cornea and the interior chamber and the lens all the way to the fundus.

And if you remember this anatomical order of the ocular structures and examine them from front to back, then you will have performed a comprehensive ophthalmic examination. The other reason that people are somewhat apprehensive about an ophthalmic examination is that they think, oh my gosh, I need all sorts of expensive equipment to perform it and actually, you don't. Here is everything that you need for a comprehensive ophthalmic examination.

There is one expensive item here, that's the tunnel pin, which we use to measure intraocular pressure. However, there is a much cheaper substitute for it that I'll mention later on in my talk. Everything else are is really rather cheap items.

We have a handle, and the handle is used to mount my direct ophthalmoscope. And myin of Trans Illuminator. This handle will usually also accept your otoscope, so really three instruments that can be mounted on the same handle.

You need a handheld lens which along with the transluminator gives you a view of the fundus or alternatively, you can use the monocular indirect ophthalmoscope, which we discussed in my previous lecture about ophthalmoscopy. You need some sort of magnification as shown here by these loops, a few strips, a few eye drops, excuse me, a few test strips, maybe some swabs, and fine forceps, and that's it. That's everything you need for comprehensive ophthalmic examination.

Actually, the most important item for an ophthalmic examination is not shown here in this picture. The most important item for comprehensive ophthalmic examination is darkness. This is not a malfunction of your computer.

Please do not try to perform an orphanic examination in a lit room. It must be a darkened room. And a darkened room with a strong light source, you can really see 90% of what you need to see just with these two conditions, a good focal light source, a thing of trans-illuminator, and a darkened room.

The other 10%. Is all the other instruments that I have shown you. But please do not try to perform an ophthalmic examination in a lit room.

I know it sounds somewhat absurd or counterintuitive, but really you'll see things much better in the dark. Two things to remember when performing a comprehensive examination is that many Eye diseases, especially in dogs, are inherited eye diseases. In fact, it is such an important topic that there are textbooks devoted to the subject.

So when my technician tells me that I have a cocker spaniel or golden retriever or whatever waiting for me in the exam room, then as I'm making my way to the exam room, I'm Already running in my head the list of inherited eye diseases in the cocker spaniel or, or the golden retriever cause there is a fair chance that my patient will be suffering from an inherited eye disease. So especially in dogs, always consider this possibility and always keep in the back of your mind the breed that you're examining. And the other important thing to remember is that, yes, maybe the patient presented for an ophthalmic disorder, but in fact, it may be an ocular manifestation of a systemic disease or a neurological disease.

And here we have two examples, a patient presenting for blindness due to cataract. But actually, it's a diabetic cataract, so that's ocular manifestation of systemic disease. And here is a patient presenting for blindness, but actually it is suffering from distemper, so an ocular manifestation of a neurological disease.

So yes, they're coming for an ocular reason, but in fact, they may be suffering from a systemic or a neurological disease. So with these things in the back of your mind, let's move on to the ophthalmic examination. And as I said, I divided into three parts.

The first part being a cross examination, looking at the patient from a distance as it is laying on the table and I'm chatting to the owner and While looking at the patient, I'm asking myself 3 questions. The first one is, are both eyes open normally? If they're not open normally, there may be two reasons for that.

Number one, maybe the eye is painful, what we call the pharospasm, as you are seeing in these two pictures, and I think these two pictures also demonstrate why this is something you want to look for when you're examining the patient from a distance, because obviously, if I walk up to this cat and I start Touching its face and handling the eye and taking a close look at the eyes, it will also start squinting in the other eye or it will open both eyes, widely. This is a rather subtle sign that will only be picked up if the cat is relaxed on the table, if I'm not threatening it or handling it. So, really something you want to look for from a distance.

Obviously, if the patient is squinting, you may be forced to use topical anaesthetic in order to, facilitate opening the eye. A very, very important point and one which I always stress in my lectures is that topical anaesthetic is only A diagnostic solution. It is not a therapeutic solution.

I've been practising veterinary ophthalmology almost 25 years now. I have never ever prescribed topical anaesthesia to a patient. It's always in my pocket.

And the reason I emphasise that is that I put a drop of topical anaesthetic in the eye of this dog, for example, the dog opens its eye and the owner looks at me and says, wow, you're a magician. 2 seconds and you've already cured my dog. No, of course, I haven't cured the dog, you know, whatever caused pain in this dog is still there, be the corneal ulcer or a foreign body or whatever.

I haven't cured anything. I just took away the pain. And sometimes I'll have owners begging me for these magical drops that took away the pain.

Never ever give the owners these drops because they'll take them home, and next time their dog or their cat, or God forbid, maybe their child will have a painful eye. They'll remember these magic drops that the vet used. They'll put them in the eye, the eye will open, they think they I think they took care of the problem when in fact they haven't.

So you never ever prescribe Tokill anaesthesia. In fact, a few of my colleagues tell me that they've had clients steal Tokill anaesthesia from the exam table when the vet wasn't looking, be very careful with their use and with their dispensation. The second reason that eyelids, the eye may not be open normally is because of eyelid problems.

There may be a prolapse of the eyelid, such as you are seeing in the right eye of this golden retriever, and if you want, you can. Pause the recording for a second and take a minute to think of why this eye is drooping. I'll be back to it in a second, or it may be a problem of eyelid conformation, entropion, ectropion excessive facial faults such as in this sharp pei.

Every once in a while, I'll be dropping you one of these advertisements if you wish, because we are today discussing ophthalmic examination, I'll be mentioning a wide variety of ophthalmic diseases. Most of them have been covered in my previous webinars and I'll try pointing you to webinars in the library which you may wish to listen to. If you want to go back and listen to a certain subject, so we did discuss I problems on September 13, 2018.

Back to the golden retriever, if you thought about it, actually, the right eye is suffering from Horner's syndrome or sympathetic denervation. You can see that in addition to the drooping upper lid of or the prolapse of the upper I did. We also have elevation of the 3rd eyelid, and we have meiosis compared the size of the two pupils.

So that's a sign of sympathetic denervation and golden retrievers are predisposed to Horner syndrome. Again, taking you back to what I mentioned earlier, many ocular diseases have a genetic or breed predisposition. So, again, the patient is still on the table.

I haven't walked up to it. I haven't touched it. I'm just looking from a distance.

I've checked to see whether the eyelids are open normally. The second thing I checked for is whether there are There are secretions, and if there are secretions, they can be divided into one of two types. One, maybe there is an excess of tears, and you can see the tear tears staying here.

And if an animal presents with a tear stain, there may be two reasons for it. Maybe there is an overproduction of tears because something is irritating the eye, for example, Eyelid or eyelash abnormalities such as entropin or dysthychia or the other possibility is that there is normal production of tears, but tears do not drain normally from the eye to the nose. Because the nasolacrimal duct is blocked somewhere and therefore tears are overflowing onto the face and these two possibilities were discussed in our webinar on lacrimal diseases last year, November 20th.

So this is one type of secretions, we are talking about tear overflow. The other possibility is that we have some sort of inflammatory or infectious secretion, so it could could be serious or mucoid or purulent discharge such as you are seeing here. If you plan to collect culture and sensitivity from this patient, please do so before you place any eye drops in the eye because most of the eye drops do contain preservatives and these preservatives will affect the results of your cultural insensitivity test.

So cultural insensitivity. Is collected before placing any eye drops, but those of you who attended my webinar from December 11, 2019 will remember that I attach minimal therapeutic importance to culture and sensitivity, both in dogs and cats. In dogs, there is little Therapeutic importance to this test because most of the infections, corneal and conjunctive infections are secondary.

There is something irritating the eye, and this chronic irritation causes an overgrowth of natural flora of the eye. And therefore, there is no point in taking cultural and sensitivity because 95% of the time, it will come back as staphylococ or streptococ or again, part of the normal flora of the eye. So instead of taking culture and sensitivity, as I said back in December, what you should do is concentrate on finding the prime.

Cause of irritation. In this case, I hope everyone can see that the primary cause is dry eye. You can see the lacklustre, cornea here pointing to the fact that this dog is suffering from a dry eye.

And in cats, there is little therapeutic importance to, the collection of cultural and Sensitivity because I know the cause of carot conjunctivitis in cats. We're talking about herpes, herpes and herpes as the three leading causes and chlamydia in 4th place. So again, why waste the owner's money on cultural insensitivity if you already know the answer.

And the third thing that we are looking for as the animal is lying on the table and we're still examining it from the distance is we look at the size of the globe and we compare the two globes to see the relative size and symmetry in size. It is obvious that there is something wrong with The left eye of this cat and the right eye of this dog. When you are faced with a non-symmetrical looking eye, you may be looking at one of two problems.

Maybe it is balmus or enlarged eye, and enlarged eye, your only differential. Is glaucoma or perhaps it is exopthalmus, exopthalmus meaning a normal eye that is being pushed forward by a retro bulbar process by a disease in the orbit, usually an abscess or a tumour that is space occupying in the orbit and pushing the globe forward and Here, in fact, you have one example of each. The dog is suffering from glaucoma and thalus, the cat is suffering from retro bulbar disease and exothalmos.

And if you want to know how I know, go back to my lecture from October 26, 2017, where we discuss how to tell exophthalmus and balmus apart. So that completes my cross examination again conducted at a distance. We are not touching or handling the patient.

We are just looking for three things. Is the eye open normally? Are there secretions and is the globe of normal size and symmetry compared to the other eye?

The second thing I'm going to check is assess my patient's vision, and vision is assessed by one of 3 methods listed here. Most commonly we'll go through all of them, but most commonly we use to test the menace response. We make a menacing gesture and watch our patient blink in response to this menacing gesture.

However, when testing the minus response, it's very important to keep in the back of your mind that it may suffer from false positive. False positive. Meaning it's positive, the patient is blinking, but it's a false positive.

It is blinking even though it cannot see you. Two possible reasons for false positives. Number one, maybe with your hand, you weren't careful.

You touched the facial hair, you touched the eyelashes, maybe your hand movement was too violent and generated an error. Current and the patient could feel the movement of air. In other words, you cause some sort of trigeminal or sensory stimulation due to touching of the hair or air currents and the patient is reacting to trigeminal stimulation.

And if you suspect that this may be the cause of the blinking, please consider performing the test behind a clear plastic or glass shield such as you are seeing here. The other possible source of false positive is the other eye. Suppose this dog is blind in the right eye and visual in the left eye.

Now, if I wasn't covering the left eye, then as I'm testing the menace response of the right eye, the dog would blink. But it wouldn't blink because the right eye is seeing me. It would blink because the left eye is seeing the menacing gesture and therefore the untested eye should always be covered because it may also be a source of a false positive.

Just like the Menu test has may suffer from false positives. It may also suffer from false negative. False negative, it's negative.

The patient is not blinking, but it's a false negative. It's not blinking even though it can see the hand. Possible reasons for false negatives include age, note that we are talking about MNS response, not MNS reflex, and one of the differences between a response and the reflex is that you're born with a reflex, but the response is something that you need to learn and the animal needs to.

Learned that this menacing gesture is a threat and that it needs to close its its eye to protect itself. So it's something that needs to be learned, it's not present in very young animals, and depending on the species, it is generally a non-useful test before the age of approximately 4 months. Another possible reason for false negative is facial nerve paralysis.

Cranial nerve 7 controls the blinking, and if it's paralysed, the animal is seeing you, but it is unable to blink. Therefore, whenever the animal is not blinking in response to a menacing gesture, what you want to do is test the blink reflex. You touch the skin at the lateral and the medial canthus and you check the blink reflex.

Now we're talking about a reflex blinking in. Responds to trigeminal stimulation of the hair at the lateral and medial canthus. Another thing to watch for if you suspect facial nerve paralysis is the third eyelid.

If the patient sees you and sees the menacing gesture, excuse me, it usually Responds by retracting the eye. Animals have a retractor pulled by muscle which allows them to retract their eye. That's an extra an extra extraocular muscle that we humans do not have.

Usually we do not. See the retraction of the globe in response to a menace because the patient is blinking and shutting its eye. However, if there is facial nerve paralysis and the patient is unable to blink, then, and it is visual, then you will be able to see the actual retraction of the globe and the passive third eyelid elevation, something to watch for if you suspect a false negative.

And finally, another possible cause of false negative may be personality, especially in cats, you know, a stoic animal that sits there on the table and, you know, it's simply not impressed by your menacing gesture. It's not impressed by anything. You can jump up and down and wave your arms about and it just sits there staring at you.

However, Take a laser laser pointer and the cat goes crazy. Cats absolutely love to follow a laser pointer. It doesn't have to be in the shape of a mouse like the one I found here on the internet.

But whenever I go to assess vision in a cat, I always carry a laser pointer in my pocket, demonstrated here. So you can see that obviously the cat is visual, maybe it doesn't have a menace, but it's responding to a laser pointer or to silent objects such as a cotton ball, you saw it in a cat, you saw it in this dog. But really, you may use any silent object.

Here is another example, oops. So you can see that obviously, this cat is visual. This is actually a cat that was blind 3 weeks previously, so we were very happy with the results of this test.

And just a couple of months ago, I got from one of my clients this high-tech 21st century visual assessment test of the cat. So obviously, the cat is seeing the moving icon on the telephone. Another way to assess vision in the patient is what is called a placement reflex.

Now we're talking about a reflex, so it may be performed in younger animals and the way you perform it is shown here. You take the animal, you hold it in the air, in your armpit. And you approach a table or hard surface.

Now an animal doesn't like to be suspended in the air, so if it is seeing the table, it extends its four limbs forward like you see in this picture. It's almost like an aeroplane extend, putting down its wheels as it comes in for landing. The Dog wants to land on the table, it's extending its legs.

So obviously here we're talking about a combination of both visual and motor pathways, but if you see this four limb extension, the placement reflex, then you know the animal is visual. So again, you can't do it in a 40 kg Rottweiler, but yes, it's something we frequently do in younger animals that have not yet developed the menu's response. And the final way to assess the patient's vision is through what we call an ACE test, or an obstacle course.

One advantage of the obstacle course is that that you can do it in both light and dark conditions and this helps diagnose inherited retinal diseases cause many patients presenting with Inherited retinopathies actually present with a loss of nighttime vision and only at later stages of the disease do they lose their daytime vision. So an obstacle course will allow you to compare their performance in light and dark and maybe get an early diagnosis of inherited retinopathy. People have a tendency when building an obstacle course to build an Obstacle course, that's suitable for a military commando unit.

You don't need to make it too complicated, just a few obstacles that can be navigated by normal age-matched animals. You can measure passage time, number of collisions. Here are two.

With demonstrating this. As I said earlier, most inherited retinopathies will begin with loss of nighttime vision, but those of you who've been in the profession long enough know that for every route, there is an exception. So yes, most inherited retinopathies begin with loss of nighttime vision, but there are a few diseases or one disease actually that begins with loss of daytime vision.

And this is demonstrated in these two movies. First one shot in the dark, and actually it's a movie shot in the dark of a black Gordon setter, so you may have a bit of problem seeing it, but here is a dog. And you can see it navigating in the dark once again.

So it's doing well in the dark. Take the same dog outdoors and OK, it's almost as if he's picking those obstacles. So an obstacle course is a way to determine the patient's vision.

The three tests we've discussed so far, the menace response, the placement reflex, and the obstacle course really assess cortical vision, but another important part of our assessment of the patient's visual pathways is the subcortical reflexes and the most notable one is the pupid or the most famous one is the pupillary light reflex. So to test the pupillary light reflex, we begin by checking the symmetry of the pupils in the light and you know the typical reflection from both eyes which helps you compare the diameter of the two pupils, then you turn off the light. And assess the symmetrical dilatation of the pupil in the darkness.

If there is anisocoria, then obviously, if an anisocoria means pupils of unequal size, then obviously the most important question you wanna ask yourself at this stage is, which is the abnormal pupil? You're seeing one meiotic pupil. One midriatic pupil, but you still don't know which is the normal one and which is the abnormal one, which I should I concentrate on.

So this comparison of the pupil diameter in light and in dark helps you determine which one is abnormal. OK, and that's shown the detailed here. If the amount of anisochoa decreased in the darkness, midriatic is abnormal.

What does that mean? Place, here is the situation in the In the light, move to the darkness. If this pupil was able to dilate in the dark, then it means that the amount of anisocoria decreased and that implies that this was the abnormal pupil.

On the other hand, place the animals . In the dark. And both pupils want to.

Dilate. This 1 may be able to dilate further. This one is unable to dilate the amount of anisocoria increased in the dark that tells you that the meiotic pupil is abnormal, so that's the way you can figure out which eye you can concentrate on.

As you know, After assessing the diameters of the two pupils, then we check the response of the pupils to a bright light stimulation and we are checking both the direct PLR and the consensual PLR. The direct PLR meaning that the stimulated eye is constricting or not and Excuse me, the consensual PLR, you stimulate one eye and you look to see whether the other eye is constricting or not, and that would help you determine whether there is an efferent or an afferent lesion in the eyes that are not constricting directly or indirectly. Another The subcortical reflex you may wish to test is the dazzle reflex.

A dazzle reflex is shown here, that is the squinting or the blinking in response to a very bright light source. Note, we are talking about a subcortical reflex. OK, we're not talking about vision.

The fact that this dog is blinking right now doesn't mean that it actually has cortical vision. We're assessing subcortical pathways, but I will be demonstrating in my upcoming lecture in January when we actually talk about blindness. It's a very important part of the workup of blind patients, the ability of the patient to respond to a bright light by blinking or the dazzle reflex.

And both the indirect PLR that I mentioned earlier and the dazzle reflex allows you very crude but quick evaluation of rein function if you cannot see the fundus. Take or cannot see the pupil. Take for example this eye full of high femur or blood in the anterior chamber.

Obviously, I cannot look at the patient's retina. I can't even assess the patient's PLR, so I really, looking at this eye, I have no way of knowing whether the retina is functioning or not. However, this patient should still have an indirect PLR, meaning that if I take a strong focal light source and place it next to the eye.

Enough light would penetrate the high femur for the other pupil to constrict. And this patient should always have a positive dazzle reflex once again because enough light will penetrate the high femur to trigger the dazzle reflex. So both of them are very cheap, quick, and useful ways to know if the retina is functioning or not when you cannot see the retina of the, or the pupil.

Note that in both cases I said a strong focal source of light. The PLR and the dazzle reflex should be tested with a thing of trans-illuminator, a fully chargedin of trans-illuminator. Don't try testing it with the light on your Phone or with the LED on the key chain, these are not strong enough, they will not trigger a dazzle or a PLR and believe me, Again, 25 years of experience talking here.

The most common reason for absence of PLR in a patient is the clinician not using a strong enough light source, OK. This is really the number one reason, and believe me, there is nothing as embarrassing as a veterinarian referring. A patient to me for lack of PLR and the patient comes in and tests PLRs and they're completely normal.

It turns out that the referring vet used a weak light source and I sort of have to talk my way out of it without embarrassing the referring vet too much. So please use a focal light source. Keeping in mind again that as I said, we are talking about subcortical reflexes and therefore normal PLR and a normal dazzle reflex do not necessarily mean that the patient.

Is visual. They will be present in blind patients. Two reasons.

One, as I mentioned, if an animal has cortical blindness, both the PLR and the dazzle will be normal because we are talking about subcortical reflex. And the other reason, which I'll come back to in my January 7th lecture, but very important to mention here as well, minimal stimulation is needed for the PLR, not for the dazzle, but for the PLR, which means that the PLR will also be present in animals with advanced cataract and inherited retinal degenerations. So yeah, .

Even if 95% of the retina is degenerated, the remaining 5% may be enough to trigger the PLR, so not much of an afferent input is required for a normal PLR, but still a very important test we'll discuss it again in January. Now, if you've been following me and you remember the order of the sequence of events, I've started by looking at the patient from a distance, checking for, excuse me, checking for where to see whether or not the eyes are opening, checking for secretions, looking at globe size. I did the evaluation of vision with a placement test or with the menace test.

I assessed the size of the pupils in the light, I turned off the light to see whether both pupils dilate symmetrically and actually right now the room is, is in dark and all the rest of my examination. When I examine the eyelids and the eyelashes and including, etc. Is now going to be conducted in the dark.

OK. Again, I said it is counterintuitive, but really the ophthalmic examination should be performed in a dark room with a focal light source and magnification. So use the thing of transilluminator that I showed earlier, use the loops that I showed you in my 3rd or 4th slide.

And And start examining the eye from front to back, beginning with the eyelid margins, and what you, what you wanna see is that the eyelid margin is in firm contact with the globe. You want to see the so-called grey line or mcutaneous junction in. Firm contact with the globe throughout the length of the eyelid.

Basically, it should look just like your eye does. Hopefully, if you look in the mirror, you will see the moans junction of your eyelid throughout the length of the eyelid. Obviously, the animal should not be sedated for this part of the examination because this will cause relaxation of the eyelids and may distort what you are looking for.

If the eyelids are not in contact with the globe, that may signify ectropion, if you are unable to see the eyelid, ectropion such as you're seeing in this dog here and in this dog here, you see that obviously the eyelid margin is not in contact with the globe. Excuse me. On the other hand, if you're unable to see the eyelid margins, such as here, then you are looking at entropion.

We can see some eyelid margin here in the nasal half of the eyelid, but we are unable to see the eyelid margin in the temporal half because it is rolled inwards. Elid problems as well as eyelash problems were discussed September 13, 2018. While examining the eyelid margins, obviously, we also inspect the eyelids themselves, really for signs of, I'd say dermatological diseases cause the eyelids are a piece of skin that just happened to be adjacent.

Into the eye, but look for signs of plephritis, which means that this dog has some sort of dermatological condition or in this case a cat suffering from squamous cell carcinoma of the eyelid. From the eyelid, we move on to the eyelashes and we examine the patient for aberrant eyelashes again discussed in our September 2018 lecture dysychia tracheosis, etc. And here we're seeing examples of aberrant eyelashes, dysychia coming from the my boing gland openings.

Here is one, here is one, here is one, here is a whole row of them. Note, especially in this right picture here, that it is much easier to see these aberrant eyelashes against the background of the white conjunctiva, OK. This dog, in fact, most of our patients has a dark hair coat and a brown iris, and it would be very difficult.

Visualise these eyelashes against the brown iris or the dark pupils. So what we're doing here is pulling the eyelid upwards, and now we can see the eyelid margin and any eyelashes that may be here against the white conuntava again not. That it's easier to see this eyelash as compared to this one.

So actually, when examining the eye, I am pulling on all four eyelids, both upper eyelids, both lower eyelids to look for the sticker and aberrant eyelashes against the white background of the conjunctiva. From there, we do move on to the conjunctiva and ask yourself if it's normal and we all know what a normal conjunctiva looks like . A normal mucous membrane and if it's abnormal, then ask yourself, am I seeing edoema, which we call chemosis or congested vessels or other signs of conjunctivitis discussed December 11th last year, or maybe we are seeing evidence of systemic diseases, cardiovascular disease in or other diseases.

We may be seeing very pale, conjunctiva in cases of anaemia, we may be seeing yellowish conjunctiva, in cases of icterus or peteria such as you're seeing here in cases of thrombocytopenia. So what's abnormal about the conjunctiva? While looking at the conjunctiva, please remember that we are not looking just at the conjunctiva of the globe, the A bulbar conjunctiva, such as we're looking here, please also look at the palpibral conjunctiva, the conjunctiva lining the inner aspect of the eyelids.

Maybe you will see some lymphatic follicles, which is what we are seeing here, these grape looking round structures. These are lymphatic follicles that indicate that this patient is suffering from conjunctivitis. And while talking about the conjunctiva, don't forget that the 3rd eyelid is really another fold of conjunctiva.

Examine the outer aspect of the 3rd eyelid by pressing on the globe, examine the inner aspect, maybe you'll find some lymphatic follicles there, or maybe you'll find a foreign body, which is what we are seeing here. So don't forget the 3rd I did. Next, in our anatomical journey of the eye, we are looking at the cornea and when looking at the cornea, Well, you know, it's supposed to be transparent and the cornea is supposed to be transparent because of 3 mechanisms shown here in the histological picture.

Number 1, it has very, it has no blood vessels and no pigment to it. Number 2, as you can see, the collagen fibres are arranged in a very orderly and parallel manner and this parallel. Arrangement of the collagen fibres is essential for maintaining transparency because it allows waves of light to pass in between the fibres.

If this orderly arrangement is disrupted, then the light is scattered, the cornea loses its transparency, and finally it's transparent because it is kept in a dehydrated state by the endothelium. If the cornea is not transparent, please ask yourself what caused loss of transparency. Is it corneal vascularization such as you're seeing here, deep vascularization, some superficial vascularization here?

Is there edoema, abscess such as you're seeing here, pigmentation, ulceration, infiltration, dystrophy, etc. Etc. .

All sorts of opacities in the cornea which were discussed in formal webinars. Moving on from the cornea onto the inside of the eye, we have arrived at the anterior chamber which is full of aqueous humour and the aqueous humour is supposed to be transparent but it loses its transparency. In cases of UVIis, intraocular inflammation, which fills up the aqueous humour with inflammatory debris such as platelets and fibrine and white blood cells, etc.

Etc. We check for the presence of this inflammatory debris in the aqueous tumour looking for a phenomenon that is called aqueous flare that is demonstrated here in these two slides. I always compare aqueous flare before I go into aqueous flare, I'll give you an analogy.

Think of yourself driving at night and you turn your headlights or your car headlights on. Now, if it's a dry night, your head, car headlights are very sharp, very focused, and they are illuminating the road ahead. However, if it's a rainy night or a foggy night, as you may frequently have in England, then when you turn on the car headlights, they are scattered.

They are not as well focused as they were on a dry night, and that's because the light is scattered when the light beams hit the water droplets in the rain or in the fog. Same thing happens in the eye when it is suffering from uveitis. Here on the left, we have a non-inflamed eye and we are looking for aqueous flare using a very fine beam of light, a slit of light, and you can see the slit of light projected here on.

The eyelid margin and on the cornea and inside the eye, it's projected on the lens, on the iris, on the pupil. So that's the inner slit. And in between them is the interior chamber and you can see that it's completely dark because it's transparent in a non-inflamed eye.

On the other hand, here on the right, we have an inflamed eye. Again, we have the outer beam projecting on the eyelids, on the third eyelid on the cornea. We have the inner beam projecting on the interior lens surface.

But note that everything between. The cornea and the lens is lit up. What was dark here is now lit up because there is inflammatory debris here that is scattering the light, just like the water droplets on a foggy night would scatter your car headlights.

Here the platelets and the fibrine and the white blood cells scatter the light. You can use this test with a slit lamp if you have one or with the smallest. Aperture of your direct ophthalmoscope and again that would show you a transparent aqueous humour versus a foggy aqueous humour as discussed in January 2019.

Actually, I was giving this lecture once in China. And I was talking about a quiz tumour. I gave the analogy of a car headlights, and then I was talking about the platelets scattering, the light and causing a quiz flare.

And after the lecture, we went to dinner and obviously we had some beer after a long day. And we had several types of beer, and then the guy next to me says, Well, here is your aquiz flair, filtered beer, unfiltered beer. Filtered beer, transparent because there are no particles, unfiltered beer, and you see all the particles causing the haze.

So, yes, that's another way to explain aqueous flair. All these inflammatory particles, the platelets and the fibrine and the white blood cells may sink into the bottom of the anterior chamber, causing what we call hypopion, which you're seeing in this raptor bird. Notice there is also traces of blood here.

You can also get bleeding in the interior chamber, what we call hyema. So look for reasons of loss of transparency of the aqueous humour. Next, we move on to the pupil behind the aquiumer.

OK. We are on anatomical journey. We started with eyelids and eyelashes and conjunctiva cornea.

Interior chamber, we are onto the pupil and when examining the pupil, look for shape irregularities, which may indicate iris atrophy, which is what you're seeing here. This was supposed to be Around pupil, but notice that there is really a missing part of the iris here, another missing part here. All that's left is this small strand.

This is an elderly dog suffering from iris atrophy. There may be posterior sicia, which is what you're seeing here. There is severe UVitis due to advanced cataract and a bit of the iris is adhered to the interior lens capsule.

So we have a distorted pupil and really a misshapen pupil here in this cat suffering from lymphoma of the iris. So that's another differential for a misshaped pupil. Which really leads us on to the Irish.

Normal pigmentation, and that explains the difference in colours of the two irises and the difference in the typical reflection. This on the other hand, is not a normal changing in colour. This is diffuse iris melanoma and this darker eye indicates that this cat suffers from uveitis and therefore the iris is more congested.

Behind the iris, we have the lens. Don't worry, we're getting close to the end of our anatomical journey. And once again, we know that the normal lens is supposed to be transparent and if it loses its transparency, it's because it's what we call a cataract.

It may start as a small opacity that sometimes may go miss, but unfortunately, most of them are progressive. And this small opacity will progress to affect a greater area in the lens. Note that most of the lens is involved here, but the eye is still not blind cause we have to put a reflection.

However, this will also progress to a mature or hyper mature in this case, cataract where the lens is completely opaque and the eye is blind as we discussed in May of last year. Please remember to evaluate the transparency of the lens following dilatation, for two reasons. Number one, it will allow you to Compare that to examine the lens both by direct visualisation and by retro illumination, which is what you're seeing here in this small puppy with cataract.

We are seeing the cataract in the left eye through direct visualisation. We're looking at it and we're seeing it. The cataract in the right eye is highlighted by the teal reflection.

We use the light reflected. Back from the tepit to highlight this opacity. We've also used it here.

We are really visualising this opacity and this opacity much better because they're illuminated by the reflection from the tepium, so use your retro illumination that requires pupil dilation and also note that there are opacities that you will not see if you have not dilated the pupil. Another important reason for dilating the pupil is that it will help you distinguish between nuclear sclerosis and cataract. Nuclear sclerosis is an ageing process of the lens.

It is not an actual pathological cataract, but frequently it may be mistaken from one. You can see it here in this picture. It does look like an opacity, .

Owners may confuse it as cataract. You may mistake it for a cataract unless you dilate the pupil and use retro illumination, and then you see that it's really only a very dense nucleus. There is some actually some peripheral cataract here, but this big opacity is just a very dense nucleus here.

Which brings us to the end of our anatomical journey and the ophthalmoscopy which we discussed in at length back in August. Again, the room must be darkened while it's been darkened throughout the examination and the pupil must be dilated. For a comprehensive ophthalmoscopic examination and really the order in which I do things is when the patient comes in, I quickly check the tumour tier test, the PLRs, and the intraocular pressure.

And then I apply tropicaide, parasympatholytic agent to dilate the pupil. Tropekomide may affect tear production, may affect the PLR and may affect intraocular pressure cause It dilates the pupil and closes the angle. So these are 3 things to check before applying tropekomide.

So, check these 3 things, apply tropekomide. Now you have 15 minutes in which you can take the patient's history. Do the complete ophthalmic examination I've described starting by the eyelashes and ending with the lens and by now the pupil is fully dilated and you are ready to do ophthalmoscopy.

We discussed it at length 4 months ago, so I'm not going to repeat the description of ophthalmoscopy. I'm only going to stress once again that please, please before. Ophthalmoscopy in every patient you examine, not just your ophthalmic patient, not just your blind patient, any patient that walks into your clinic, whether it's for vaccination or dermatological problem or diarrhoea, because number one, it's a complex technique and you need practise in order to master it.

And number 2, as we said in August, there is lots of normal variations in the appearance of With normal fundus, and if you haven't looked at it enough, normal animals, you will never be able to diagnose a retinal problem in a blind animal. So please practise ophthalmoscopy in every patient you you examine. I always tell my students, please think of your ophthalmoscope as your stethoscope, just like you wouldn't dream of examining a patient without doing auscultation and using your stethoscope, don't dream of examining your patient without a brief ophthalmoscopic examination, to see what the fundus looks like and to gain proficiency in this test.

And finally, 3 quick ancillary tests I'd say in every red eye, please be sure to measure tear production by doing the Schirmer tear test and diagnosing dry eye. In every red eye, please don't forget to stain the cornea, be it with rose bengal staining for superficial epithelial defects usually caused by herpes virus or with fluorescent staining which will stain stromal ulcers and In every red eye, please measure intraocular pressure, beat it with the shield's indentation tornometer, which is the cheaper alternative that I mentioned in my 2nd or 3rd slide, but hopefully, your clinic can afford one of the modern. Aclination or rebound tonometers, the tonne of pen or the tonovet.

So three essential tests, Schmer, fluorescent staining, and tonometry are to complete your ophthalmic examination of every patient. As usual, this is now a recorded lecture. I can't answer your questions, but please feel free to mail them to the office and they'll be forwarded to me.

I promise to answer, and because you are not with me in the room, I bring my own applause. Thank you very much for your attention, seeing you in January when we talk about blindness. Thank you.