How To Perform Optic Nerve Examination - Cranial Nerve II Examination OSCE - Dr Gill

[Music] so with cranial nerve - we're not simply dealing with a sensory nerve but there's also a motor component which is how they optic nerve controls the people to contract the ciliary muscles before we can actually go on to test the eye we actually need to make sure the patient's got a good vision which we're going to do with a Snellen chart so we'll get the patient if they're wearing glasses or contact lenses for that matter to do the examination with the snail and child reading which is the lowest line they can read so on the side of the chart it will frequent to say for example 20 over 20 that's considered to be normal vision ie you can't read at 20 meters what a normal person can read at 20 meters surprisingly the UK limit for driving is 12 over 20 some other thing about that if the patient doesn't have their glasses with them then we can use a pinhole because that will remove any refractive error from their vision some perhaps you might want to try yourself get a piece of paper and put up and often it will hole maybe with the end of a pen or pencil and if you've got any problems with your vision take your glasses off and look through that dot look through that hole and then if we put that hole up to the camera we should be able to focus through it but rather than just looking at the table let's try something more interesting and then if we take the piece of paper and look through the hole we can see that Bob's eyes become much much closer into focus so without and with without with and hopefully you should see that your vision whilst narrowed by the very small dog is actually clearer now as clear as when you normally have your glasses on so now we need to actually see how well you your vision is so do you wear glasses normally yes okay do you have them with you okay and if you had any changes to prescription recently okay so if you look at my face is my guess I need black splotches my missing a night perfect so what I'd like to do to start off with behind me is a snow on chart so could you cover your right eye for me okay what's the lowest line you can read on there you start from the left Lee's a perfect just swap eyes if you put your hand over your right eye what's the lowest line you could read get and start from the right side of the paper perfect so we've got no problems there now some of the cranial nerve to do blend over so a good example is cranial nerve to so when we shine the light in the patient's eyes we're looking to make sure the pupil constricts however that message is being carried up by cranial nerve to but the constriction message in action is actually done by cranial nerve three the oculomotor so I'm just gonna go over here and when we're checking between one eye and the other we need to make sure that there aren't any unusual responses so we should expect both eyes to contract when the light is showing them when checking the pupil response it's worthwhile to make sure you're moving the torch under the nose as opposed to across the eyes that way you're reducing light bleed some people will like to put a hand over the nose so it reduces that light bleed from one eye to the other even more when we assess the eyes like this we want to check that the pupils are perler pupils equal and reactive to light and accommodation so we've checked the light going across each pupil but we also need to get the patient to focus on something close to them and then also focus on the wall further away when the patient's eyes come back to look at the close object we should again see accommodation so constriction of the pupil and the next thing if you look at my finger and then it was sealing behind me no matter the finger superb in terms of a relative afferent pupillary defect there are several things that could cause this how to think amongst yourselves and if you've got any ideas as what those could be so potential causes of a relative afferent pupillary defect would be multiple sclerosis I hope you're seeing a theme here diabetes problems with the retina itself retinal detachment and retinal infox all of which stopping the signal going up the cranial nerve - we also need to be aware of another condition called a Argyll Robertson pupil this is due to tertiary syphilis when the syphilis has reached the brain and damaged the optic nerve here the pupil is said to accommodate but not react ie if you shine the torch between the eyes the pupil will remain constant but when you get them to look at something close and then far away you'll see the expectant changes there's one further abnormality that we need to be aware of with regard to the pupils and that's if we have Horner's syndrome that's a triad of three things ptosis miosis anhidrosis so the patient will find that they have difficulty raising up the eyelid the upper eyelid will be drooping down that have meiosis a very small pupil that doesn't dilate when we take the light away and anhidrosis the failure of sweating on the affected side of the face that is due to something pressing on the neck potentially a Pancoast tumor arising from the lung causing pressure on the sympathetic chain impairing that function so once we've confirmed that the eye is working with the Snellen chart we can see how it's working and that's worthwhile to give an itchy horror chart as if explained in some of the previous videos where we can see what the nature of the patient's color vision is and that can be quite important for one particular condition particularly multiple sclerosis if there's a problem with the optic nerve and a patient will get what's called a red desaturation that they're red on the side that's affected won't look for want of a better phrase as red as it would do otherwise often you'll see neurologists using a hatpin because nobody else needs happens these days so what we'd get the patient to do is we assure them that happen and we're getting to put a hand over one eye and see how red the top of a hat pen looks we then get them to swap over eyes and see whether or not there's any red desaturation by comparison ie to the top of the hat pen look the same on both sides however as I say you can't just use a red topped pen in terms of confirming the size of the blind spot we need to move the red dot or the hat pin around inside our blind spot confirming when we can see it and making sure that a patient can see it in those same areas this is very important it's because of diabetes causing damage to the retina specifically cotton walls bombs if we've got demyelinating diseases such as multiple sclerosis or if we have problems with hypertension which would also damage the retina when I called you a blind spot so if you could hand over one eye for me okay and I want you to only look into this eye here and at some point as I move the pen across the pen will disappear or the pen top wrong okay so if it's gone now I'm gonna carry on moving it across and tell when it reappears look okay I gotta get backwards says it okay now telling it reappears thank you okay so um okay I'm gonna go up there okay and then down done super okay and last one count back back excellent so we swap over to the other rifleman again looking at why I hear it's a ton one it disappears done okay tell me it reappears okay just a minute just begun okay fine I'm not going up okay excellent so your blind spot lines up well with mine there but thank you I appreciate that's a slightly difficult test today we'd want to get hold her an ophthalmoscope I don't want to have a look at the back of the patients eye checking on the retina if we're going to be assessing the optic nerve we need to make sure that we understand that the retina is actually the most external facing part of that optic nerve and on the retina we'll be able to assess for papilledema any evidence have raised intracranial pressure we then need to assess the patient's fields of vision I doubt we're going to get the patient to sit a meter away from us and we're going to have them close their right eye to look into our left get the patient to fix their vision to yours and not move their head or their eye from there move your arm in an arc on the lateral aspect of their vision to see whether or not they can see your finger waggling at the edges of gaze do the same again with your opposite hand to check the medial side of their vision there are many things which can affect the visual quadrants how much of the retina is functioning to those being raised intracranial pressure as mentioned but also for churchy trimmers which can give characteristic appearances in terms of mapping out the patient's uh visual field in terms of loss of the visual fields there are three key findings that we want to look out for the first bent by temporal hemianopia where the patient can see directly in front of them but has lost the vision to the edges of their periphery this can be seen in meningitis and asthma in a optic chiasm compression from a pituitary tumor and that's sitting directly over the optic nerve here if this little bulb grows in size then it's going to put pressure on that crossover of the optic nerve and is going to cause us difficulty with vision loss specifically after bitemporal hemianopia almost opposite to bitemporal hemianopia we should have by nasal hemianopia where we are losing the inside part of the vision that tends to be a vascular problem in the optic radiations at the back on the inside of the brain whether art this is a stroke or other vascular problem that blockage there as I say will feed back down the optic nerve in order to lose the middle part of the vision you can also have homonymous hemianopia where you are losing sight on one side of the retina however the lesion is opposite to where the problem lies so for example if a patient has a lesion in the left hemisphere then it will cause right-sided homonymous hemianopia so to put that one back together when we're testing the visual fields we are using our fingers as moving markers and we want to make sure that the patient can see our finger coming in from the side at the same point that we're seeing our finger coming in from the side if there's a difference there then when we can see the finger but the patient can't then that's indicating that they don't have functioning sight in that part of the retina and that will then tell us which part of the brain is being affected and potentially lead us to our diagnosis so now we're going to see how well your eyes work on the very side so we're going to look at your peripheral vision it so I'm just gonna make sure on the right distance away so you can see my finger wagging yep tell money to see my finger yep yep yep yep yep yep so figured to swap eyes for me okay I need to see my finger wagon yep okay please stay looking on this side I'm telling you see my finger yep yep yep yep yeah okay [Music]