Show notes
This is the first episode of this program, so I’m still putting things together. You can listen to the show with the links above. I’m having the episode transcribed, but this will take a few days. in the meantime, I’ve copied my show outline below in case you want to read it while listening. Also, you can subscribe to this podcast using iTunes … just search for “Eye Basics” in the iTunes store, or go directly to the podcast page here. Show Transcript (comments below) This is Eye Basics 101 Episode 1: The Basic Eye Exam In a world without good eye education, a beacon of hope was born. That beacon is Eye Talk Radio Welcome to Eye Basics 101. This is an audio program dedicated to teaching you about the eye and ocular disease. No matter if you are a student, a practicing doctor or just a curious person wanting to learn more about the eye, we can all learn more with thoughtful discussion. My name is Dr. Timothy Root, I’m a general ophthalmologist and cataract surgeon. The show notes for this episode are available at eyetalkradio.com, that’s E-Y-E eyetalkradio.com. If you have questions or comments about today’s discussion, just visit the show notes. You can also find it directly at Eyebasics101.com. Just look for episode 1 and leave a comment if you have one. Today’s topic is the basic eye exam. Now, sight is arguably the most important sense for both survival and quality of life. The eye exam is quite different than a medicine exam. If you are a medical student or practicing doctor, much of your training to this point has probably involved a basic whole body exam. The eye is quite different. For one thing, it’s much smaller, the eyes are only about one inch in diameter. It’s one of the smallest organs we can actually examine but there is a lot to see. And the reason why is the cornea, that clear window on the front of the eye lets us look inside the eye, so a lot to examine, a lot to document and it’s all crammed into a tiny space. But before we get going on the basic eye exam, I wanted to spend a little bit of time talking about the motivation behind this program and why are we doing with this. When I was an ophthalmology resident, I had a great fortune of spending a good month up in New York City rotating with a neuro-ophthalmologist. During that time, I had to do quite a lot of self-study to try to understand a very confusing topic, neuro-ophthalmology is one of the more difficult sub-specialties to comprehend. I found a series of audio lectures recorded by the great neuro-ophthalmologist J. Lawton Smith back in the 70s. They were online so they put them up in a novel website and I downloaded all the mp3s and loaded them on my mp3 player. As I commute around the city, I would listen to this lectures and they were pretty dense. Neuro-ophthalmology, talking about neuro anatomy in an audio format was quite challenging but I did find the experience extremely enlightening and very educational for me. I really enjoyed listening to these lectures and hear Dr. Smith talk to me right into my ears. It was quite moving. I don’t know if you have ever had any familiar idea with J. Lawton Smith. He died a couple of years ago but he was one of the great neuro-ophthalmologists of the past 50 years. He worked down at Bascom Palmer down in Miami, Florida but he was from South Carolina and he was famous for his teaching style and partly because he just had a really interesting way of speaking, had an extremely dense Southern Carolina accent and he would say things like, pure as Ivory soap and you’re a rube and all these crazy Southern Carolina backward sayings. It’s really funny, it’s strange it can’t come with such an accent and such a great intellect. I found the entire experience very interesting, the audio was fantastic. I enjoyed the dialogue, I think it made me a better doctor. I’m not saying I’m a J. Lawton Smith, that’s for darn sure, but I did find the experience listening to the audio while walking around quite good because reality is, I do a lot of videos. If you have ever seen my videos online, I do a lot of online video lectures, you’ll find them on YouTube. But people only have so much screen time, so much time where they’re sitting in front of the computer screen or looking on their phone or doing that type of stuff because life is busy. I’m hoping that by putting this in an audio format, it will be portable, you will be able to listen to it while driving around, walking around, cleaning the house doing chores and also maybe a little bit more personal because I can spend a little bit more time talking to you. There’s also some selfish reasons behind this whole audio endeavor because the preparation time is much less. I put together a video lecture, I try to do a good job and it takes me months to put together lines and record the videos and then edit the audio into it and fix the timings, put it into a down loadable video format, upload it online. It’s a big ordeal and my family is not wild when I go into video mode. But audio, I could probably whip up pretty quickly. In fact, I’m scheduling to do it bimonthly so we’ll see what is quite as useful. But with that other way, let’s go back on topic. We’re here today to talk about the eye exam, the basic eye exam. Now, this is actually a challenging topic even though it’s supposed to be basic, this is challenging. The reason why is talking about exam techniques is extremely boring. I dreaded doing this topic but I knew I had to get it done because you can’t really talk much about ophthalmology or optometry without learning how to actually looking at the eye itself but extremely boring topic.In fact, when I was a medical student, they would make us read, I believe it was called the Bates clinical exam, this was this big giant hardbound book on how to examine the human body, how to percuss the lungs and to listen to the heart and t examine the lymph nodes. It was an extremely boring book. I bought the darn thing as I was supposed to but I never cracked it open because it was just overwhelming. How do you learn the body exam through a textbook? In fact, that book was so big they give us a pocket version for carrying around with us which I did look at. Learning how to do an examination technique is kind of like reading a passenger safety instruction when you’re on an airplane. I mean, who really does that? It’s really boring. Or maybe read a manual on refrigerator maintenance. It’s not the type of thing that necessarily lends itself towards the written, or even the spoken word. These things are important so we’re going to talk about it because we got to do it, you got to start somewhere and this is a good place to start. If you’re going to be an awesome doctor or eye doctor, you got to know how to examine the eye. My challenge, in fact, it’s not even challenge, it’s my responsibility to you, is can I present this information in a way that’s both educational and still entertaining and you’re going to be a judge at that because I don’t know but we’re going to do our best so bear with me and let’s get going. The first topic I want to go over is vital signs. Now in medicine, the vital signs are the blood pressure, the heart rate, temperature, respirations, these are all measurements of essential body functions. When I say essential, if you have no blood pressure, heart rate, temperature, you are essentially dead, right? Well, oddly enough, despite the importance of these vital signs, in ophthalmology, that nearly is important. I mean, if you could walk into an eye doctor’s office, your vital signs are actually good enough. Instead, we have completely different vital signs and I’m not sure if this is something books teach but this is what I teach my own students. The vital signs of the eye are the vision, the pupils, and the eye pressure. I’ll say that again, vision, pupils, pressure. These are the essential ocular functions. They are essential because if you have no vision, what were the eyes for? Pupils are nice objective measurement and pressure is vitally important for glaucoma. Vision, pupils, pressure, vision, pupils, pressure. It’s like a mantra. In fact, you need to get a patient’s vision, pupils, pressure before you can put dilating drops in which doesn’t sound like important points but when you’re an ophthalmology resident and you get called at two in the morning to the emergency room to see a patient, you have to get their vision, pupils, pressure before you can put those dilating drops in. Those dilating drops are going to take 15 to 30 minutes to work and so if you want to get sleep, you got to get that vision, pupil, pressure first so that you can get those drops in. And so, I kind of feel like the Dunkin Donut man, I don’t know if you remembered this old commercial from the 80s but he would wake up early in the morning and say, “Time to make the donuts.” It’s the same thing with the eye. “I got to check the vision, pupils and pressure.” Because this is very important, let’s spend some time on each of these vital signs and going to these in a little bit more detail. Number one, vision. Arguably, of all the vital signs, the vision is the most important function and interestingly, despite its importance, vision is very hard to measure sometimes. It’s inherently a subjective measurement. No one man’s blurry vision is another man’s clear vision. And so, in an attempt to objectify this measure of a patient’s vision, we had to come up with something and so the most commonly used measurement is the eye chart, how good is your vision. Most doctors use the Snellen eye chart. It was invented by Dr. Herman Snellen back in 1862 but it’s basically the eye chart with the big E on the top and as you go down, the letters get smaller and smaller and smaller. The Snellen eye chart is normally documented as some type of ratio. A patient with 20/20 vision is considered to be a normal person but if someone has, let’s say, 20/60 vision, what that means is if you have your patient standing at 20 feet looking at the eye chart, they could only read the 20/60 line where someone with normal vision standing 60 feet back from that eye chart can read just as good. It’s kind of a ratio of how good is your vision compared to how someone else with normal vision is. We use the 20 foot marking here in America and the US but the rest of the world uses different measurement, they’re on the metric system and so they do a meter convention and they usually do 6 meters. Let’s say 20/200, in other countries would be a 6/60. Same ration number comes out to being the same, just different measurements used. There is another type of eye chart called a logmar eye chart that is typically used with research. It has a little bit more even progression between the line. Every line has the same number of letters on it so it’s probably more technically accurate but the Snellen chart is pretty much standard so 20/20 vision Snellen, that’s how we document it. As far as how to measure someone’s vision, it was pretty obvious. You check each eye one at a time, see how well it can read that eye chart. But there’s a couple of points I ‘d like to emphasize here before we move on. The first point is that the corrected vision is really the only important measurement here. People always want to know what’s their vision without glasses. It doesn’t matter because patient’s vision with the glasses or with the best corrected vision is the only thing that’s important because that tells us how healthy the eye is. Sure, you may be nearsighted or farsighted, it doesn’t matter. We only really check patients with corrected vision. Unless there’s some other reason you need to know what their vision is without glasses, for example, the driver’s license bureau might want to know if this person can drive a car safely without her glasses, so then we check but on routinely, I don’t always bother checking uncorrected version because it doesn’t really tell me anything. Also, we check one eye at a time typically and you can do that by using the occluder a little paddle that covers one eye at a time. There’s also the paddle that covers both eyes that has a little hole in the middle of it. The important thing when checking someone’s vision one eye at a time is people cheat. They totally cheat. You really have to watch them closely which is why the occluder panels are good because you now they’re not peeking between their fingers. You have to watch little children especially because they will cheat at the drop of a time [0:12:01.6], they are not being malicious, they just do it. Also, some of our older patients especially in glasses, when their hand would drift, they don’t realize it either. So one eye at a time. This is obvious stuff, right? Another technique we use is the pinhole technique. If you have a patient who doesn’t see perfectly, one trick you can do is have them look through an occluder that has little tiny holes punched through it. By doing that, if they ended up seeing significantly better, this implies that maybe their glasses aren’t quite up to date or they need glasses or change in that prescription. The reason why is when you look through a pinhole, this turns your eye into a pinhole camera. I’m not going to go too much on the optic here to explain how this works but I’ll do it a little bit. A pinhole camera, I don’t know if you have ever seen one of these things but it looks like a box that’s dark inside with a little tiny hole punched into one wall. You can make one of these using an old coffee tin for example, you just punch a little tiny hole on the lid, put some photographic film on the bottom of the thing and then you set it stable somewhere. The theory behind it is if you have a small enough hole going into this camera, light coming off of specific object will come through that hole inside the camera and hit a single spot on the film at the back of the camera. Light from a different area will always go through that hole and hit a single spot so everything is in focus. It doesn’t matter how close or how far away that object is, light can only split through that little tiny hole so it comes in straight and strikes a single space in the back of that camera. Pinhole camera is always in focus, distance, near, it doesn’t matter. It doesn’t even need to be focused. Pinhole cameras are nice in that way. A lot of small cellphones have pinhole cameras in them and if you notice, using a cellphone, there’s not a whole lot of focusing, everything is kind of in focus. Nicer cellphones have cameras down and they do focus but little tiny spy cameras, little tiny camera phones, they have pretty good focus. Compare this to a big giant SLR camera, those things you have to focus perfectly because if you don’t things are out of focus because they have a nice, big aperture. The bigger the hole going into the camera, the more you get to focus. SLRs take great pictures because you get that wonderful blurring effect in the background so you could really focus on your object. But the point being pinhole turns your eye into a pinhole camera so things come on focus. If your patient ends us seeing a lot better when you put that pinhole occluder up there, it kind of implies that maybe, they need to be focused better. Maybe, their glasses are out of of wack because they need glasses. But the pinhole technique, we do that one eye at a time typically. It will all come back to this pinhole especially if we are talking about cataracts but now, let’s move on. Another technique that we can use on checking vision is called the BAT or BAT test, it’s the brightness, acuity, tester technique. The idea behind it is you check your patient’s vision and you shine a flashlight in her eye, a little pin light right next to their eye and you see if it creates any glare problems, if their vision drops off a lot. If it does drop off a lot, they kind of implies maybe there’s a cataract because a cataract has a cloudy lens inside the eye and if it’s cloudy, i…
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