The examination starts really when the dog walks into the room, that we have a hands-off examination just looking at the conformation of the head, the way the eyes sits in the orbits. Is there discharge? Is there any indication of pain? That sort of thing. And of course, while we're taking the history, again, we're just checking the animal. So once we've completed the history, which of course is very important, and we have this cursory examination of the dog without touching, then we start to touch. And so there's a hands-on examination that usually involves instrumentation, very simple instrumentation as well. That you can do a very, very good clinical examination just using a simple focal light source, something like this, simple focal source. But you turn the lights off in the room. And then you've got the eye in the light source. And because of this transparency, all sorts of lesions become very, very obvious. If we want a little bit of magnification, then we use a condensing lens. So the combination of these two things can give you the whole examination. Because as I'll show you in a few moments' time, we can use this as an ophthalmoscope to actually examine the retina. All right, well now, if we are a little bit upmarket, then we can combine focal light source and magnification in an instrument called the slit lamp, the slit lamp biomicroscope. And this is an instrument, which gives you binocular vision and magnification and a light source. And it has the facility to allow us to use a slit beam. And that slit beam means that we can pick up opacities in cornea and lens in the plane of light so that on either side of that slit everything is dark. But in the slit, you see the opacity. And this has the distinct advantage of allowing you to estimate the depth of the lesion. If cataract is present in the lens, you'll be able to say whether it's the front or the back or in the middle. Again, with the cornea, that you'll be able to say whether the opacity is at the front, the back, or the middle. And that's important because of differential diagnoses. So that's a slit lamp biomicroscope. We would then, having examined the cornea and having examined the anterior chamber and having examined the lens, we would then do some other things, but these involve a dye, a fluorescein dye to stain up corneal erosions. That we would run a thing called a Schirmer tear test to estimate the amount of aqueous phase that there is in the pre-corneal tear film. And we would use some drops that go by the brand name of Mydriacyl, tropicamide. These drops are used to dilate the pupil so that we can then get a really good look at the lens and the retina. And to look at the retina, we use an instrument that's called an ophthalmoscope. There's two types of ophthalmoscope. There's this guy, which is the direct ophthalmoscope. This is very easy to use. By just placing the ophthalmoscope against the bridge of your nose, you then gaze through a hole in the head of the ophthalmoscope along a light beam. And you're looking directly at the fundus. You obtain focus by simply rotating a disk in the head of the ophthalmoscope, which has got lenses of different strengths in it. So we can look at the lens in the dog's eye with this instrument. But primarily, we use it to look at the retina. And the alternative to the direct ophthalmoscope is the indirect ophthalmoscope. And this consists of a headset. This is the headset. It's got a light source. And we simply strap it to our head like so. And then with binocular vision, we're looking along that light beam. And we use a lens that we hold about 5 centimeters in front of the cornea to image the back of the eye. It's an aerial image. So it's upside down and reversed, but it's bright and sharp. You get stereoscopy. And it is the ideal way to examine, particularly, the dog's fundus. If we can't afford this level of equipment, then we can use our focal light source and lens as an indirect ophthalmoscope. And again, it's just a matter of holding the light source at the level of one's eye and, again, picking up the image in the lens, this aerial image of the fundus. Having completed an examination without touching the dog, we can then get to touching. And as I said earlier on, we need a focal light source. We need the lights out in the room. And we can see any abnormality of eyelid, anything happening in the conjunctiva, the cornea, and, beyond that, the iris, and, obviously through the pupil, something of the lens. If we want to look at that with a little bit of magnification, then we can use a condensing lens and just illuminate the eye. And with a bit of magnification, we'll be able to see the lesions that we've already picked up with some detail-- so a very simple focal illuminator and the condensing lens, about 20 diopters. If in fact we do have a slit lamp biomicroscope available, then this gives us binocular magnification. We've got a full beam, again, looking at abnormalities in the eyelids, the globe itself, the conjunctiva, the cornea, the iris, the pupil, and so forth. And this slit beam facility that allows us to look at planes of the ocular structure, and this helps us to localize the depth of opacity within the cornea and the lens. As far as looking at the lens is concerned, we said that we need to dilate the pupil. And so we are using drops to open the pupil right up. And then the slit lamp allows us to look at the lens in all its glory. That we are looking at the fundus too, once the pupil has been dilated, using the ophthalmoscope. And this is the direct ophthalmoscope. We place this to our eye, put the beam of light on the dog's eye. And if there's corneal opacity or lens opacity, we'll pick that up with what's called distance direct ophthalmoscopy. And then we get in as close as possible to the eye so that we're looking through that lens at the dog's fundus. That's the direct ophthalmoscope. But for indirect ophthalmoscopy, well, I showed you the headset together with a condensing lens, but the lens is placed about 5 centimeters in front of the dog's eye. And then we pick up an aerial image in the lens, which is upside down and reversed, but bright and sharp. And we've got stereoscopy. So it's a very useful way of examining the fundus. It's much more useful than the direct ophthalmoscope in that we get at least three times the area of view in the one field. And if we don't have a headset, then we can use our focal illuminator to do the same thing. Again, the lens is held about 5 centimeters in front of the cornea. If you could open the lid, Paul? Can you open the lid? And then the light source held at the level of one's eye at about arm's length, and then there's this image that's obtained in the lens. Just by moving the lens backwards and forwards, you'll pick up the image of the fundus just as easily using this system, the cheap system, as you will with the headset. Earlier, I talked to about other mechanisms of examination. And I mentioned the use of a stain. We use fluorescein. It's on a sterile strip. And that's used to demonstrate erosions on the surface of the eye. And we just wet the strip with the sterile saline and then just stroke across the corneal surface. And the fluorescein is taken up by the corneal stroma. And we will demonstrate erosion. It's important to do that with any animal that presents with anterior segment pain. It's also important to run this little test. This is the Schirmer tear test. And the Schirmer tear test involves inserting this little strip of sterile filter paper, basically, into the conjunctival sac and watching the speed at which this gets wet. Other drugs that we use, well, I said that we like to use Mydriacyl to dilate the pupil to give us access to the lens and the fundus for a complete examination. And the only other drug that is useful is this topical analgesic, proxymetacaine hydrochloride, that we use to desensitize the cornea and the lids so that in the painful situation it's easier for us to run the examination.