WEBVTT
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Hello, my name is Parl Kator MD.
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I'm an ophthalmologist in Atlanta, Georgia, specializing in cataract and glaucoma surgeries.
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After practicing medicine for over a decade, I have learned that the more a patient knows about their disease, the better they do.
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Patient education is a passion of mine.
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But like most doctors, I have a lot of patients and not a lot of time to see them.
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So I created this podcast where I could spend the time I don't have during the day to give you insights into the eyeball and ocular disease.
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Let's empower you as a patient or a patient support system.
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Together, let's demystify the eye.
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Hello, and welcome back to another episode of Demystify the Eye.
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I was helping my fifth grader with her math homework yesterday.
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Have you ever seen the show Are You Smarter Than a Fifth Grader?
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It was a really big game show in the 2000s.
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In the show, a fully functioning adult with a career would be pitted against, yes, you guessed it, a fifth grader, to test their fund of knowledge.
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What's the difference between a stalactite and a stalagmite?
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Which countries fought in World War I?
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The best part was the math section.
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That is when the adults would really start to sweat as they solved math equations across from a four foot eight blonde with a high ponytail.
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Well, let me tell you what I realized, folks.
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I am not smarter than a fifth grader.
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I am definitely not.
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But then again, of course I'm not.
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I don't spend my day dividing fractions anymore or solving algebra equations with the proper order of operations.
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My day-to-day math skills are now limited to calculating a restaurant bill tip or calculating the overall cost differential between a 30-year fixed mortgage versus a 7-1 arm.
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But there is one more place I still flex my math skills.
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That's at work in a space that gives many of my colleagues a bit of nausea.
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It's something called optics.
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Optics is basically an understanding of how light enters the eye and gets focused into an image that is crisp and clear.
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Optics is generally everyone's least favorite course in an ophthalmology residency.
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It feels like you are back in college level two physics or back in fifth grade doing your math homework.
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However, it is an essential skill to know down pat if you are going to be a cataract surgeon.
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Or for those of you listening, it's an important skill to understand if you are about to have cataract surgery.
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In this episode, we will make sure you understand the basics of optics so you can walk into your cataract surgery consultation feeling confident.
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Refraction.
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Let's start with the term refraction.
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Refraction in my world is the measurement of an eye's ability to focus light.
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I want you to imagine an eyeball that we cut in half lengthwise.
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Now split the eye in two.
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And if you are eating, maybe put this podcast on pause.
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Remove one half of the eye and swivel the remaining half around so that you are looking at the inside of the eyeball.
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I want you to think about the front of the eye or cornea on the left and the optic nerve of the eye on the right.
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Let's quickly review the structures of the eye from the left to the right.
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On the left side, you have the cornea, which is a clear dome.
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It's the window of our eye and light enters through it first.
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The next structure behind the cornea is the iris.
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That's the colored portion of our eye.
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The hole in the center of the colored portion is called the pupil.
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Behind this pupil is our lens.
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When we are born, this lens is crystal clear, but as we get older, it gets cloudy, and that cloudiness is called a cataract.
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Behind the lens is a large space filled with jelly called the vitreous cavity.
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Diving deeper, we hit the retina, which is the layer of tissue that plasters the back wall of our eye.
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It is like the film in the camera.
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It takes all the pictures for us.
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It sends those pictures to our brain for processing via a structure in the very back of our eye called the optic nerve.
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That's a quick and dirty review of eye anatomy.
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If you want to pause this and get a more detailed review, please check out the podcast labeled Eye Anatomy.
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Now that we remember eye anatomy, we can understand optics.
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I want you to picture light entering an eye through the cornea on the left side.
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Think of this light as a bunch of parallel, tiny beams of light.
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If those parallel beams passed through the eye just as they are, they would hit the retina in the back of the eye at multiple points, all at the same time.
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Our entire retina would light up with information and this would be sensory overload.
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Also, all this scattered light would create a very blurry image.
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No, that's definitely not the way to see.
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Instead, we want to take those parallel beams of light and focus them into a single point of light that only lights up one portion of our retina.
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This is the way to get a crystal clear image.
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There are two powerhouse structures in our eye that focus the light.
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The first is our cornea, and the second is our lens.
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As those parallel beams of light enter our cornea on the left, they start bending towards each other.
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Next, our iris blocks out a bunch of those beams of light, only allowing a select few to move forward through the pupil.
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Thanks, iris.
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Without you, we would have a lot more bending work to do.
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The remaining beams of light go through the lens and the lens bends them even more.
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They begin to converge and continue converging or coming closer together inside the vitreous cavity until they hopefully all converge perfectly onto our retina.
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That's quite a trip light has to take to get to one single point.
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Can you imagine that this process occurs all day, every day, every time we look at something?
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I had a good friend once who was a hypochondriac.
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He was convinced something was wrong with him at all times.
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He called me up one day convinced he was losing vision from a horrible eye disease.
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So I saw him in the office.
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His vision was 2020 without any glasses or any contact lenses.
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His eyes were perfect.
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I knew he would not walk out of my office without a diagnosis.
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He simply had to have something.
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So I turned towards him at the end of the exam and I said very gravely, Well, my friend, turns out you have emetropia.
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Oh my God, I knew it.
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I just knew it.
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What is that?
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What does this mean?
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I told him emetropia was a very official medical term.
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It meant his eyes could focus light perfectly, without the need for any glasses or contacts.
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I am not sure he appreciated my diagnosis, but it was the only one I could give him.
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The lens then bends the light just the right amount more, so the light rays hit the retina as a perfect point, creating a perfect, crisp, clear picture.
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You lucky ducks with emetropia are like those unicorn humans that are born with perfectly straight teeth.
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Yes, the rest of us peasants can get to your level of vision, but we need to go through some hoops to get there.
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How many people are emotropic?
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Well, it depends quite a bit on your age, country of origin, and ethnicity.
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The statistics vary widely.
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It's estimated about half of people in the United States over the age of 20 have been gifted with emetropia.
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If you have not, it means you have a refractive error.
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And the first one we will cover is near and dear to my heart.
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Myopia.
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So I wear glasses and contacts, and my prescription has a minus in it.
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If I was an emetrope, my prescription would be zero.
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The more minus a prescription, the more myopic someone is, and the harder it is for them to see in the distance.
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To give you an example, my patient is a minus 1.5 diopters in her glasses prescription.
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Diopters is the measurement of refractive error in an eye.
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This means she cannot read the 2020 line on the eye chart, but she can maybe see the 2040 line without glasses.
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She could go for a walk in the park, but if she watches TV, she needs her glasses, so she can see the facial expressions of her show's characters.
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In the next room over, my patient is a minus 7 diopter myope.
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He can only make out the big E on the eye chart without his glasses.
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He would not want to go for a walk in the park as he might get lost.
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And forget about watching TV.
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Myopia means the combined cornea and lens are too powerful at bending or refracting light.
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The light rays end up coming together as a point in the vitreous, which is the jelly in the back of the eye.
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They come together in front of the retina.
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After the light rays come together to form a point, guess what they do?
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They diffract or spread apart again.
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This means by the time they hit the retina, the light rays are scattered, forming a blurry image.
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What does the cornea look like if it is too powerful?
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It is very steep.
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Think about Epcot Center for a moment.
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That is the perfectly round dome next to Disney World in Orlando.
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Imagine taking that dome, cutting it in half, and making it steeper.
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When light hits the dome, it will get bent at a much sharper angle.
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We measure the steepness of the cornea in diopters and can measure yours using a tool called a corneal topographer.
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When a developer looks at a parcel of land they purchase, they take a topographic measurement of the land.
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They can tell where the land is steep and where it is flat to understand how to level the ground to build a house.
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A corneal topographic map shows us where your cornea is steep and where it is flat, and it allows us to measure how steep and how flat that cornea landscape is.
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So if the cornea and lens bend the light too much, it comes together as a point in front of the retina.
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But we see cases of myopia, even when the cornea and lens are average in their ability to refract light.
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How can that be?
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Well, you can get myopia if the eye is too long.
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If the eye is super long, the refracted light will have to travel a very far distance to reach the retina.
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If the cornea and lens only bend that light an average amount, it will run out of steam before it can travel this whole length.
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We can measure the length of the eye using a machine in our office called a biometer.
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We can also use an ultrasound machine to do the same thing.
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So we can tell if you have an average length eye, short eye, or long eye.
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If you have a combination of a long eye with a steep cornea, you are likely pretty darn nearsighted.
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Your prescription may be a minus 11 or a minus 15 or a minus 20.
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Hyperopia.
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Now let's talk about the opposite scenario.
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Hyperopia is our second refractive error, and in layman's terms, we call this being far-sighted.
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This means a person can see far away without glasses, but they cannot read or see up close.
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Hyperopic patients have a plus in their prescription.
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Just like myopia, there are different levels of severity of hyperopia.
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Someone can be a mild hyperope with only a plus one in their prescription.
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They can likely read a book on their Kindle if they enlarge the font.
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Or someone might be a plus five diopter hyperope, in which case there is simply no way they can read anything arm's length in without reading glasses.
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In hyperopia, the combined cornea and lens are not powerful enough.
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When light rays pass through these structures, they do not get bent enough.
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This means they end up coming together at a point behind the retina.
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When they hit the retina, just like in myopia, they are scattered, creating a blurry image.
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In hyperopia, the cornea can be too flat.
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Think about someone pushing their finger on the top of Epcot center and smushing it down.
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A flat cornea cannot bend light rays very well.
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Just like in myopia, a hyperobe can have a cornea that is not too flat, just average steepness.
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In this case, the eye is too short.
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Imagine a cornea and a lens that bend light, an average amount.
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That light then travels through the vitreous and would come to a point right on the retina.
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But the eye is short, and so the light rays hit the retina way sooner than expected.
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If a patient has both a flat cornea and a short eye, they are probably quite hyperopic or far-sighted.
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They likely have a pretty big plus in their glasses prescription.
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Astigmatism.
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Now, for a refractive error that really bugs a person, we will talk about astigmatism.
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With astigmatism, the cornea or the lens, or both, are not round and smooth.
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They are lumpy, bumpy.
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So when light rays pass through this lumpy, bumpy cornea, they get bent at all different angles.
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To understand this, think of a ray of light that passes through a cornea normally.
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The rays on the outside of the cornea should get bent more than the rays on the inside of the beam of light.
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The light rays at the very center should not get bent at all.
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They should go straight through.
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If the outer rays don't get bent more than the inner rays, the light beam has no chance of coming together at the same time into one fine point.
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In astigmatism, thanks to the lumpy, bumpy cornea, this does not happen.
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The rays of light on the outside might hit a bump and get bent less than the rays of light on the inside that hit a lump.
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With the rays going all different directions, they can never hit the retina at the same point at the same time.
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It does not matter how long or how short the eye is.
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What does a glasses prescription with astigmatism look like?
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Well, there are actually three parts to a glasses prescription.
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If you or someone you know wears glasses, take a look at theirs.
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The first number in the prescription refers to myopia or hyperopia.
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Do the light rays come together as a point in front of the retina or behind the retina?
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This first number is called a sphere.
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The second number in the prescription is called the cylinder.
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And this number refers exclusively to astigmatism.
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If you do not have astigmatism, your prescription will only have one number to it.
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If your prescription has three numbers, you know you have astigmatism.
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What's the third number for?
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It helps us understand where your cornea is lumpy or steep.
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Astigmatism is really annoying because images are blurry no matter where you look.
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In the distance or up close.
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There's really no good area of vision, no sweet spot.
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Presbyopia.
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Presbyopia is a humbling refractive error because it's the one that lets you know you are officially getting old.
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Presbyopia is when we are no longer able to see up close without the help of reading glasses.
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This happens because we lose our ability to accommodate after the age of 40.
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Accommodation means the ability to shift your vision from distance to near and back to distance again.
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Think about playing a game of tennis.
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Your opponent serves the ball and you watch the ball go over the net and come towards you.
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You watch that ball as you hit it with your tennis racket and then watch it sail away.
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You are able to accommodate thanks to the flexibility of the lens in the front of your eye.
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Remember, that's your second refracting structure, located just behind your pupil.
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Muscles in your eye push and pull the lens to change its shape from fat to skinny, and this changes how powerfully light is bent.
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Remember that imaginary eyeball I made you conjure up before?
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The light rays enter the eye as parallel beams of light and then get bent by the cornea and lens.
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This is true for objects that are in the distance.
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But when the object is close to the eye, light rays come off the object like a funnel.
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They are divergent or spreading out when they hit the cornea as opposed to coming in parallel.
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So they need to be bent even more to get to one single point on the retina.
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The lens goes from skinny to fat, so it has more power to bend the light more.
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Pretty neat, huh?
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The problem arises when the lens begins to harden.
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Then it can no longer go from fat to skinny to fat to change its refracting power.
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This unfortunately occurs for every single human being starting at the age of 40.
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That's right.
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All of us.
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Every single one.
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It's what I've tried to explain to my six-year-old.
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Every time she shoves her art project four inches in front of my face and says, Mama, look, see, I have to gently scoot her arm back, and I'm noticing with each year that passes, I have to scoot it back farther and farther and farther.
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I'm still fine in the distance, but I can no longer shift my focus to see closer in.
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Diagnosis.
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I used to be famous for one of my party tricks back before I started going to bed at 9 p.m.
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Anyone at the party who was wearing glasses would come see me, and I could guess their prescription simply by looking at the way their face looked through their glasses.
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And I guessed it right every time.
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I mean every time.
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This is because glasses for myopia or nearsightedness are concave lenses.
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Okay, talk about going back to fifth grade math.
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Let's dust off that shelf in our brains for a second.
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Concave lenses, if you will remember, are lenses that are skinny in the middle and thick on the edges.
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Convex lenses, on the other hand, are fat in the middle and skinny on the edge.
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To correct myopia, we have to use a concave lens.
00:20:32.799 --> 00:20:36.079
The skinny in the center lens minimizes objects.
00:20:36.319 --> 00:20:42.799
This is true for the person wearing the glasses as well as the person looking at someone's face through their glasses.
00:20:42.960 --> 00:20:49.200
So the edge of their face where their glasses fall will suddenly jump inwards and their eyes will look small.
00:20:49.359 --> 00:20:54.720
If you see someone with a very high myopic prescription, their eyes might look tiny.
00:20:54.960 --> 00:21:00.960
Hyperopic glasses, on the other hand, are corrected with convex lenses that are fat in the middle.
00:21:01.119 --> 00:21:03.279
This will make objects look larger.
00:21:03.440 --> 00:21:10.240
I call these glasses anime glasses because they give someone really large eyes relative to the rest of their face.
00:21:10.480 --> 00:21:20.079
If you've ever watched the show AP Bio on TV, you'll immediately notice one of the students, Heather, has a very high hyperopic prescription.
00:21:20.319 --> 00:21:24.079
Her glasses look like she's looking through the bottom of Coke bottles.
00:21:24.319 --> 00:21:32.400
Before 1949, we used to do cataract surgery by removing a patient's cataract, but we did not replace it with an artificial lens.
00:21:32.640 --> 00:21:33.279
Why?
00:21:33.519 --> 00:21:35.839
Well, they hadn't been developed yet.
00:21:36.079 --> 00:21:40.880
So everyone was left aphaic, meaning with no lens.
00:21:41.200 --> 00:21:44.799
So one half the eyes powerhouse refractor was gone.
00:21:45.039 --> 00:21:53.279
Most folks needed a very high plus lens around a plus 11 diopter lens in order to be able to see.
00:21:53.519 --> 00:21:58.160
It was pretty easy then to spot those people who had had cataract surgery.
00:21:58.400 --> 00:22:11.279
Thankfully, these days, We do put artificial lenses back in the eye after we remove a cataract, and those artificial lenses come with all different powers to match the needs of that particular eye.
00:22:11.519 --> 00:22:17.279
These days, we can get patients out of glasses they have used for years with cataract surgery.
00:22:17.519 --> 00:22:21.839
To diagnose your refractive error, you would want to see your local eye doctor.
00:22:22.000 --> 00:22:28.640
They will likely put you in a machine called an autorefractor that will give a starting point for your prescription.
00:22:28.880 --> 00:22:33.440
This prescription will then be fine-tuned with a manifest refraction.
00:22:33.680 --> 00:22:37.279
This is where you do the better one or better two test.
00:22:37.519 --> 00:22:41.759
As someone with a high prescription myself, I hate this test.
00:22:42.000 --> 00:22:48.400
Every time I take it, I think of that song, under pressure, coming down on me.
00:22:48.720 --> 00:22:57.920
But then I take a deep breath and remember, true eye professionals get a good gestalt of what a person actually needs by the way they answer.
00:22:58.160 --> 00:23:02.799
They know when I am being greedy for more prescription than what I actually need.
00:23:03.039 --> 00:23:06.000
Something common in us myopes, by the way.
00:23:06.240 --> 00:23:15.920
It's always a great idea to bring your glasses in to every eye appointment because we won't know if you need a change in your glasses unless we know what's in your current glasses.
00:23:16.160 --> 00:23:24.720
Like fortune tellers, we can take your glasses and put them in a machine called a lensometer and read the actual prescription in them.
00:23:24.960 --> 00:23:32.000
I once had a patient ask me to be careful not to shake his glasses too much or some of his prescription might fall out.
00:23:32.319 --> 00:23:40.319
Fortunately, as we know now, this prescription is not a magic liquid, but rather based on the shape of the lens.
00:23:40.559 --> 00:23:50.240
Still, I was exceedingly gentle with my patient's glasses because when you are blind as a bat, glasses are magical after all.
00:23:52.720 --> 00:23:53.680
Treatment.
00:23:56.240 --> 00:24:00.319
So now that we know what a refractive error is, how do we treat it?
00:24:00.559 --> 00:24:09.599
In medicine, we like to categorize things from least invasive to most invasive, and we will do the same with treatment options for refractive errors.
00:24:09.839 --> 00:24:12.799
So let's begin with good old glasses.
00:24:13.039 --> 00:24:20.480
These can treat every type of refractive error, including astigmatism treatments and presbyopia treatments.
00:24:20.720 --> 00:24:28.880
Have you ever gotten a glass's prescription from your eye doctor and felt like you were in algebra looking at a boggle of numbers that made no sense?
00:24:29.119 --> 00:24:34.240
Well, after today, a glass's prescription won't look like hieroglyphics anymore.
00:24:34.480 --> 00:24:37.599
The first number in your glasses prescription is your sphere.
00:24:37.839 --> 00:24:43.519
This will tell if you are nearsighted or myopic or far-sighted, hyperopic.
00:24:43.759 --> 00:24:50.720
If you are myopic, this number will have a minus in front of it, and if you are far sighted, it will have a plus in front of it.
00:24:50.960 --> 00:24:58.960
An easy way to remember this is to think about the phrase, he is thinking myopically, which means to think short-sightedly.
00:24:59.200 --> 00:25:00.720
This is not a compliment.
00:25:00.880 --> 00:25:04.400
It's usually a criticism, so it's a minus.
00:25:04.799 --> 00:25:10.880
Some people only have one number in their prescriptions, which means these lucky ducks do not have astigmatism.
00:25:11.039 --> 00:25:16.160
If you have a second and a third number in your prescription, it means you do have astigmatism.
00:25:16.400 --> 00:25:19.839
Remember, astigmatism means the cornea is lumpy bumpy.
00:25:20.000 --> 00:25:22.640
There are steep parts and there are flat parts.
00:25:22.880 --> 00:25:32.799
The second number tells us how much astigmatism you have, how wonky shaped is your eye, and the third number tells us where the steep and the flat areas are.
00:25:33.039 --> 00:25:47.920
If you look at the eye and imagine it is a clock, 3 o'clock is what we call zero degrees, and 9 o'clock is 180 degrees, 12 o'clock is 90 degrees, and 6 o'clock is 270 degrees.
00:25:48.160 --> 00:26:04.240
So if my prescription had a plus 0.5 as the second number and an X90 as the third number, it would mean my cornea was flat at 90 degrees and steep at 180 degrees.
00:26:04.480 --> 00:26:11.440
Some four opters are calibrated for plus cylinder and some four opters are calibrated for minus cylinder.
00:26:11.599 --> 00:26:14.000
Why are they not all calibrated the same?
00:26:14.319 --> 00:26:16.960
That would simply be too easy, folks.
00:26:17.200 --> 00:26:26.240
We measure astigmatism in diopters, and we human beings can tolerate up to 0.7 diopters of astigmatism without being bothered.
00:26:26.480 --> 00:26:34.079
For example, I have 0.75 diopters of astigmatism in my left eye, I don't even bother correcting.
00:26:34.400 --> 00:26:39.839
We consider 0 to 1.5 diopters of astigmatism to be mild.
00:26:40.079 --> 00:26:49.359
1.5 diopters to 3 diopters is considered moderate, and anything over 3 diopters is considered significant astigmatism.
00:26:49.759 --> 00:26:59.039
If you see the words add at the end of the prescription and then a fourth number, it means you have an extra reading prescription in your glasses.
00:26:59.279 --> 00:27:03.279
The higher this fourth number, the closer you have to hold things to read.
00:27:03.440 --> 00:27:10.480
So if you were looking at your computer 20 inches away, you might need a plus 1.25 add.
00:27:10.960 --> 00:27:17.599
But if you are holding a book 14 inches from your face, you might need a plus 2.5 reading edition.
00:27:17.920 --> 00:27:23.440
Patients ask me all the time what prescription they should get for their over-the-counter reading glasses.
00:27:23.599 --> 00:27:30.160
And much to their chagrin, my answer is always, it depends, because it does.
00:27:30.400 --> 00:27:34.319
It depends on how far away they want to be from whatever they are looking at.
00:27:34.480 --> 00:27:45.519
So I suggest they go to the store and pick a magazine off the shelf and pull out their iPhone and then hold that magazine or phone where they want to hold it, not where they can currently see it.
00:27:45.680 --> 00:28:00.640
Then I instruct them to try different reading glasses, maybe a plus 1.5, and if it's not clear, try going up to a plus 1.75, then a plus two until they find the glasses that work for their working distance.
00:28:01.119 --> 00:28:06.400
So, bifocals or progressives, which one should you choose?
00:28:06.640 --> 00:28:10.400
Well, there are advantages and disadvantages to each option.
00:28:10.559 --> 00:28:17.039
With bifocals, there is a line in the glasses that demarcates the distance from the reading prescription.
00:28:17.200 --> 00:28:21.119
It's really easy to find where each portion of the glasses is.
00:28:21.599 --> 00:28:30.640
But many of my patients feel like this line in the glasses is basically a giant neon sign saying, I'm old, I need reading glasses.
00:28:30.960 --> 00:28:36.240
Progressives, on the other hand, have no line, so you can still look young and fresh.
00:28:36.559 --> 00:28:46.160
In these glasses, the prescription gradually transitions from distance at the top to intermediate somewhere in the middle to the reading prescription at the bottom.
00:28:46.480 --> 00:28:54.000
You definitely want to get progressives made at a reputable place so the transition can be as smooth as possible.
00:28:54.240 --> 00:28:58.880
These glasses are great for the person that does a lot of intermediate things.
00:28:59.039 --> 00:29:01.839
Think desktop, computer, or gardening.
00:29:02.079 --> 00:29:05.359
And also a lot of near things closer to their face.
00:29:05.599 --> 00:29:09.440
Think woodworking or sewing or reading at 14 inches.
00:29:09.759 --> 00:29:14.160
Progressives can give this patient the multiple different optical zones they need.
00:29:14.400 --> 00:29:23.440
However, patients can sometimes complain of not being able to find the sweet spot in these lenses because of the multiple optical zones.
00:29:23.680 --> 00:29:33.359
If you do get progressives, I would recommend making sure you get large enough glasses to fit everything in easily, meaning the lenses should be nice and tall.
00:29:33.519 --> 00:29:38.720
Think Velma from Scooby-Doo as opposed to piano teacher glasses.
00:29:39.519 --> 00:29:42.640
Treatment contact lenses.
00:29:44.319 --> 00:29:45.839
Glasses are easy.
00:29:46.000 --> 00:29:47.759
They are also fashionable.
00:29:47.920 --> 00:29:52.960
And as many of my patients point out, they can cover the bags under your eyes.
00:29:53.200 --> 00:29:55.440
So why not just stick with glasses?
00:29:55.680 --> 00:29:59.839
Well, the issue comes when your prescription starts getting large.
00:30:00.079 --> 00:30:07.440
Because of the shape of the lens, glasses for myopia will minimize objects, making them smaller than they appear.
00:30:07.680 --> 00:30:15.680
When you have a prescription like me, I'm a minus 7.5, this can create vision that is just a little off.
00:30:15.920 --> 00:30:19.680
If you are far-sighted with a high prescription, things are magnified.
00:30:19.920 --> 00:30:24.319
If you have a reading ad in your glasses, things get magnified even more.
00:30:24.720 --> 00:30:30.400
Think about if your prescription is a plus four, and then we have a plus two reading ad.
00:30:30.640 --> 00:30:39.920
That means the reading portion of the glasses is a plus six, and that is a huge magnifier that will also create visual distortions.
00:30:40.160 --> 00:30:41.920
These glasses will be heavy.
00:30:42.079 --> 00:30:45.119
Mine give me a headache after a full day of wear.
00:30:45.359 --> 00:30:48.319
And they can really reduce peripheral vision.
00:30:48.480 --> 00:30:53.200
Not really a great idea when you are, oh, for example, driving.
00:30:53.759 --> 00:31:01.119
And when you are running or in a downward dog, it is really not fun to keep pushing these glasses back up your nose.
00:31:01.359 --> 00:31:07.200
It doesn't happen often, but imagine if you have a different prescription in one eye versus the other.
00:31:07.440 --> 00:31:15.839
If you are nearsighted in one eye and then far-sighted in the other, well, objects will be smaller in one eye and larger in the other.
00:31:16.079 --> 00:31:29.440
This is called anisaconia, and it makes for some really uncomfortable vision as your brain tries to mesh these two slightly different sized images together into one coherent image.
00:31:29.759 --> 00:31:32.960
These reasons are why contacts were created.
00:31:33.119 --> 00:31:35.359
Contact lenses are amazing.
00:31:35.519 --> 00:31:38.480
I've been wearing mine since I was 10 years old.
00:31:38.799 --> 00:31:48.640
However, it is critical, and I mean really critical, to only choose this option if you are committed to practicing good contact lens hygiene.
00:31:48.880 --> 00:31:53.119
This means always washing your hands when handling contacts.
00:31:53.359 --> 00:32:02.079
Never, ever, like ever, sleeping in them overnight or storing them in anything other than proper contact lens solution.
00:32:02.400 --> 00:32:07.599
No tap water or I shudder as I say this, spit.
00:32:08.000 --> 00:32:08.640
Yuck.
00:32:09.200 --> 00:32:17.279
Also, not using your contacts longer than they were intended to be used and always giving yourself a contact lens holiday.
00:32:17.519 --> 00:32:27.839
No, this does not mean we ship our contacts to Hawaii for a vacation, but rather that we take one day a week to not wear our contacts so our eyes have a chance to breathe.
00:32:28.079 --> 00:32:38.319
Here's a fun fact: the closer a person's prescription is corrected to their retina, remember that's the tissue that plasters the back wall of the eye, the sharper that vision is.
00:32:38.559 --> 00:32:45.519
Glasses sit an inch or so away from the front of your actual eyeball while contacts sit on your actual eyeball.
00:32:45.759 --> 00:32:48.319
So contacts will give you clearer vision.
00:32:48.559 --> 00:32:56.319
Contacts don't change the size of images, so they are great if you have a high prescription or a different prescription in each eye.
00:32:56.559 --> 00:33:00.319
These days, contacts can correct quite a bit of astigmatism.
00:33:00.559 --> 00:33:03.519
These contacts are called toric contacts.
00:33:03.680 --> 00:33:06.720
These days, contacts even have a reading prescription in them.
00:33:06.880 --> 00:33:07.680
It's true.
00:33:07.920 --> 00:33:15.920
These contacts are called multifocal contacts, and they come with low or high reading powers depending on how close you like to hold things.
00:33:16.079 --> 00:33:17.359
Do they really work?
00:33:17.759 --> 00:33:22.960
Well, not for everyone, but if you are able to tolerate them, they are pretty neat.
00:33:23.200 --> 00:33:30.319
One night I wore a multifocal contact lens in one eye and a regular distance-only contact lens in my other eye.
00:33:30.480 --> 00:33:36.319
I was able to read my menu with a multifocal contact eye, but with the other, no way.
00:33:36.799 --> 00:33:38.640
Everything was blurry.
00:33:38.960 --> 00:33:43.839
The other neat thing about contacts is you can try something called monovision.
00:33:44.160 --> 00:33:48.079
This is where we correct one eye for distance and the other eye for reading.
00:33:48.240 --> 00:33:52.240
Then both eyes work together to give you a range of vision in between.
00:33:52.480 --> 00:33:56.240
Word of warning: not everyone can tolerate monovision.
00:33:56.480 --> 00:34:02.079
I put both my parents in monovision contacts in preparation for eventual cataract surgery.
00:34:02.319 --> 00:34:05.200
My mom took to it like a fish in water.
00:34:05.519 --> 00:34:08.159
My dad hated it from the get.
00:34:08.480 --> 00:34:12.239
He was like, wait, why did I pay for your med school?
00:34:12.480 --> 00:34:16.239
Some brains just don't like dissociated vision.
00:34:16.480 --> 00:34:29.599
When we make one eye for distance and one eye for near, we take away your depth perception, and this can really bother some folks, while others' brains will use extra visual cues to make up for this lack of depth perception.
00:34:29.760 --> 00:34:33.599
But if you're a tennis player, monovision may not be right for you.
00:34:33.840 --> 00:34:43.920
If you have a corneal scar or a significant amount of astigmatism, think over three diopters, then you might really benefit from hard contact lenses.
00:34:44.079 --> 00:34:47.119
We call them gas permeable lenses.
00:34:47.360 --> 00:34:55.360
Because they are a hard shell, they will force a really wonky cornea into as round and smooth a shape as it can possibly get into.
00:34:55.760 --> 00:34:59.039
Hard contact lenses make some people shudder.
00:34:59.199 --> 00:35:02.719
The ones from the 80s and 90s make me shudder.
00:35:02.880 --> 00:35:09.599
However, technology has changed and hard contact lenses are much, much easier to tolerate these days.
00:35:09.840 --> 00:35:13.519
Some people even prefer them to soft contacts.
00:35:14.960 --> 00:35:18.000
Treatment, artificial lenses.
00:35:19.679 --> 00:35:24.000
Could we get even closer to the retina than contact lenses?
00:35:24.239 --> 00:35:25.760
Why, yes, we can.
00:35:25.920 --> 00:35:30.079
We can put the correction for your refractive error right into your eye.
00:35:30.320 --> 00:35:36.239
We do this during cataract surgery after we remove your clouded natural lens or cataract.
00:35:36.400 --> 00:35:44.079
Light contacts, artificial lenses come with astigmatism correction and can have a reading prescription built into them.
00:35:44.320 --> 00:35:49.119
For more information, listen to the podcast on artificial lenses.
00:35:49.440 --> 00:35:52.960
Can we correct your prescription right up next to the retina?
00:35:53.519 --> 00:35:54.559
No, not yet.
00:35:54.800 --> 00:35:55.760
But you never know.
00:35:56.000 --> 00:35:59.119
Technology is advancing every day.
00:36:01.199 --> 00:36:02.719
Conclusion.
00:36:04.960 --> 00:36:10.960
I did a medical mission trip to Nicaragua with one of my partners when I first started at my practice.
00:36:11.199 --> 00:36:17.599
I had done medical mission trips before to Haiti, but this was the first one in my specific field of ophthalmology.
00:36:17.840 --> 00:36:22.320
As a doctor, it was hands down the best week of my life.
00:36:22.559 --> 00:36:23.119
Why?
00:36:23.360 --> 00:36:28.159
We went into a village and set up a rudimentary clinic in any available building.
00:36:28.320 --> 00:36:31.199
It was nearing 100 degrees without air conditioning.
00:36:31.360 --> 00:36:33.039
No patient had insurance.
00:36:33.280 --> 00:36:39.760
There was no such thing as prior authorizations, no electronic medical records, no pharmacies to shop out.
00:36:40.000 --> 00:36:42.719
We came with whatever treatments we could dispense.
00:36:42.880 --> 00:36:47.119
This was mostly in the form of glasses, though we did have some drops with us.
00:36:47.360 --> 00:36:51.440
These glasses were donated by people who no longer needed them in the U.S.
00:36:51.840 --> 00:36:57.440
Some pairs were Gucci and Prada, and some looks like they were created in the 60s.
00:36:57.599 --> 00:37:01.840
We had a simple check-in table where volunteers would get a brief history and vision.
00:37:02.000 --> 00:37:04.400
The patients then came to my partner and I.
00:37:04.559 --> 00:37:10.800
We didn't have any fancy machines, just the absolute basic handheld equipment you could think of.
00:37:11.039 --> 00:37:18.559
We figured out our patient's problem and then gave them glasses or advised them to go to the nearest medical center six villages over.
00:37:18.800 --> 00:37:21.840
No credit cards were accepted, no billing was sent out.
00:37:22.000 --> 00:37:28.559
My office manager never gave me that look that tells me I'm running two hours behind, so need to stop talking so much.
00:37:29.039 --> 00:37:32.639
I'll never forget an old man who entered our clinic.
00:37:32.880 --> 00:37:39.360
He was a very thin but wiry man who had ridden his bicycle 50 miles to reach our clinic.
00:37:39.679 --> 00:37:40.800
Barefoot.
00:37:41.119 --> 00:37:43.760
He had left at four in the morning.
00:37:43.920 --> 00:37:51.920
He could not speak any English, but communicated with the biggest smile that showed off his remaining two or three teeth.
00:37:52.159 --> 00:37:56.239
The phrase blind as a bat could have been written for him.
00:37:56.480 --> 00:37:59.280
He could not make anything out on the eye chart.
00:37:59.440 --> 00:38:03.360
It turns out he had had cataract surgery with a medical team.
00:38:03.599 --> 00:38:08.320
They couldn't put a new artificial lens in his eye and didn't have any glasses for him.
00:38:08.480 --> 00:38:14.480
His cataract had been huge, so his vision was better than it had been, but not much better.
00:38:14.719 --> 00:38:18.719
His prescription without an artificial lens was a plus eight.
00:38:18.880 --> 00:38:21.119
That's a very large prescription.
00:38:21.360 --> 00:38:25.760
We dug in our bag, and lo and behold, we had a pair of glasses.
00:38:26.000 --> 00:38:30.400
Only one pair, mind you, with his exact prescription.
00:38:30.639 --> 00:38:37.760
We put it on his face, and it was like watching one of those videos where a baby sees his mother's face for the first time.
00:38:38.079 --> 00:38:40.639
It was revelatory.
00:38:41.039 --> 00:38:42.800
Game changing.
00:38:43.199 --> 00:38:47.760
Now, along with his big, non-toothy grin, were tears.
00:38:48.159 --> 00:38:49.679
A stream of them.
00:38:49.920 --> 00:38:52.639
When he left our clinic, we all got hugs.
00:38:52.800 --> 00:38:55.760
He walked out of the clinic with so much confidence.
00:38:55.920 --> 00:39:02.159
Right as he got to the threshold, he jumped in the air and clicked his bare heels to one side, then the other.
00:39:02.400 --> 00:39:07.280
It's a moment that is imprinted in my brain.
00:39:07.519 --> 00:39:19.840
Each day I do fancy surgeries and use cutting-edge technology, but I try never to forget that sometimes the simplest of treatments can be life-changing.
00:39:20.320 --> 00:39:24.480
Until next time, see well and be well.
00:39:48.800 --> 00:39:52.239
Then why do you always tell me that it's really gross?
00:40:04.800 --> 00:40:06.239
Creepy for me.
00:40:07.519 --> 00:40:11.360
Okay, well, you have plenty of time to change your mind.
00:40:11.679 --> 00:40:12.559
Thank you.
00:00:01.439 --> 00:00:04.639
Hello, my name is Parl Kator MD.
00:00:04.799 --> 00:00:10.320
I'm an ophthalmologist in Atlanta, Georgia, specializing in cataract and glaucoma surgeries.
00:00:10.480 --> 00:00:18.640
After practicing medicine for over a decade, I have learned that the more a patient knows about their disease, the better they do.
00:00:18.879 --> 00:00:21.839
Patient education is a passion of mine.
00:00:22.000 --> 00:00:27.280
But like most doctors, I have a lot of patients and not a lot of time to see them.
00:00:27.519 --> 00:00:36.560
So I created this podcast where I could spend the time I don't have during the day to give you insights into the eyeball and ocular disease.
00:00:36.719 --> 00:00:40.719
Let's empower you as a patient or a patient support system.
00:00:40.960 --> 00:00:44.719
Together, let's demystify the eye.
00:00:58.000 --> 00:01:03.840
Hello, and welcome back to another episode of Demystify the Eye.
00:01:04.079 --> 00:01:07.200
I was helping my fifth grader with her math homework yesterday.
00:01:07.359 --> 00:01:10.480
Have you ever seen the show Are You Smarter Than a Fifth Grader?
00:01:10.879 --> 00:01:13.599
It was a really big game show in the 2000s.
00:01:13.760 --> 00:01:24.079
In the show, a fully functioning adult with a career would be pitted against, yes, you guessed it, a fifth grader, to test their fund of knowledge.
00:01:24.319 --> 00:01:28.079
What's the difference between a stalactite and a stalagmite?
00:01:28.319 --> 00:01:30.640
Which countries fought in World War I?
00:01:31.280 --> 00:01:34.079
The best part was the math section.
00:01:34.239 --> 00:01:44.000
That is when the adults would really start to sweat as they solved math equations across from a four foot eight blonde with a high ponytail.
00:01:44.239 --> 00:01:47.680
Well, let me tell you what I realized, folks.
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I am not smarter than a fifth grader.
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I am definitely not.
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But then again, of course I'm not.
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I don't spend my day dividing fractions anymore or solving algebra equations with the proper order of operations.
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My day-to-day math skills are now limited to calculating a restaurant bill tip or calculating the overall cost differential between a 30-year fixed mortgage versus a 7-1 arm.
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But there is one more place I still flex my math skills.
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That's at work in a space that gives many of my colleagues a bit of nausea.
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It's something called optics.
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Optics is basically an understanding of how light enters the eye and gets focused into an image that is crisp and clear.
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Optics is generally everyone's least favorite course in an ophthalmology residency.
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It feels like you are back in college level two physics or back in fifth grade doing your math homework.
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However, it is an essential skill to know down pat if you are going to be a cataract surgeon.
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Or for those of you listening, it's an important skill to understand if you are about to have cataract surgery.
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In this episode, we will make sure you understand the basics of optics so you can walk into your cataract surgery consultation feeling confident.
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Refraction.
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Let's start with the term refraction.
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Refraction in my world is the measurement of an eye's ability to focus light.
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I want you to imagine an eyeball that we cut in half lengthwise.
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Now split the eye in two.
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And if you are eating, maybe put this podcast on pause.
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Remove one half of the eye and swivel the remaining half around so that you are looking at the inside of the eyeball.
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I want you to think about the front of the eye or cornea on the left and the optic nerve of the eye on the right.
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Let's quickly review the structures of the eye from the left to the right.
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On the left side, you have the cornea, which is a clear dome.
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It's the window of our eye and light enters through it first.
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The next structure behind the cornea is the iris.
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That's the colored portion of our eye.
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The hole in the center of the colored portion is called the pupil.
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Behind this pupil is our lens.
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When we are born, this lens is crystal clear, but as we get older, it gets cloudy, and that cloudiness is called a cataract.
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Behind the lens is a large space filled with jelly called the vitreous cavity.
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Diving deeper, we hit the retina, which is the layer of tissue that plasters the back wall of our eye.
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It is like the film in the camera.
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It takes all the pictures for us.
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It sends those pictures to our brain for processing via a structure in the very back of our eye called the optic nerve.
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That's a quick and dirty review of eye anatomy.
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If you want to pause this and get a more detailed review, please check out the podcast labeled Eye Anatomy.
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Now that we remember eye anatomy, we can understand optics.
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I want you to picture light entering an eye through the cornea on the left side.
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Think of this light as a bunch of parallel, tiny beams of light.
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If those parallel beams passed through the eye just as they are, they would hit the retina in the back of the eye at multiple points, all at the same time.
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Our entire retina would light up with information and this would be sensory overload.
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Also, all this scattered light would create a very blurry image.
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No, that's definitely not the way to see.
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Instead, we want to take those parallel beams of light and focus them into a single point of light that only lights up one portion of our retina.
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This is the way to get a crystal clear image.
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There are two powerhouse structures in our eye that focus the light.
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The first is our cornea, and the second is our lens.
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As those parallel beams of light enter our cornea on the left, they start bending towards each other.
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Next, our iris blocks out a bunch of those beams of light, only allowing a select few to move forward through the pupil.
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Thanks, iris.
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Without you, we would have a lot more bending work to do.
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The remaining beams of light go through the lens and the lens bends them even more.
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They begin to converge and continue converging or coming closer together inside the vitreous cavity until they hopefully all converge perfectly onto our retina.
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That's quite a trip light has to take to get to one single point.
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Can you imagine that this process occurs all day, every day, every time we look at something?
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I had a good friend once who was a hypochondriac.
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He was convinced something was wrong with him at all times.
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He called me up one day convinced he was losing vision from a horrible eye disease.
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So I saw him in the office.
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His vision was 2020 without any glasses or any contact lenses.
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His eyes were perfect.
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I knew he would not walk out of my office without a diagnosis.
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He simply had to have something.
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So I turned towards him at the end of the exam and I said very gravely, Well, my friend, turns out you have emetropia.
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Oh my God, I knew it.
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I just knew it.
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What is that?
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What does this mean?
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I told him emetropia was a very official medical term.
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It meant his eyes could focus light perfectly, without the need for any glasses or contacts.
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I am not sure he appreciated my diagnosis, but it was the only one I could give him.
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The lens then bends the light just the right amount more, so the light rays hit the retina as a perfect point, creating a perfect, crisp, clear picture.
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You lucky ducks with emetropia are like those unicorn humans that are born with perfectly straight teeth.
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Yes, the rest of us peasants can get to your level of vision, but we need to go through some hoops to get there.
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How many people are emotropic?
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Well, it depends quite a bit on your age, country of origin, and ethnicity.
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The statistics vary widely.
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It's estimated about half of people in the United States over the age of 20 have been gifted with emetropia.
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If you have not, it means you have a refractive error.
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And the first one we will cover is near and dear to my heart.
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Myopia.
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So I wear glasses and contacts, and my prescription has a minus in it.
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If I was an emetrope, my prescription would be zero.
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The more minus a prescription, the more myopic someone is, and the harder it is for them to see in the distance.
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To give you an example, my patient is a minus 1.5 diopters in her glasses prescription.
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Diopters is the measurement of refractive error in an eye.
00:10:03.840 --> 00:10:11.279
This means she cannot read the 2020 line on the eye chart, but she can maybe see the 2040 line without glasses.
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She could go for a walk in the park, but if she watches TV, she needs her glasses, so she can see the facial expressions of her show's characters.
00:10:19.600 --> 00:10:24.559
In the next room over, my patient is a minus 7 diopter myope.
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He can only make out the big E on the eye chart without his glasses.
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He would not want to go for a walk in the park as he might get lost.
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And forget about watching TV.
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Myopia means the combined cornea and lens are too powerful at bending or refracting light.
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The light rays end up coming together as a point in the vitreous, which is the jelly in the back of the eye.
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They come together in front of the retina.
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After the light rays come together to form a point, guess what they do?
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They diffract or spread apart again.
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This means by the time they hit the retina, the light rays are scattered, forming a blurry image.
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What does the cornea look like if it is too powerful?
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It is very steep.
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Think about Epcot Center for a moment.
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That is the perfectly round dome next to Disney World in Orlando.
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Imagine taking that dome, cutting it in half, and making it steeper.
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When light hits the dome, it will get bent at a much sharper angle.
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We measure the steepness of the cornea in diopters and can measure yours using a tool called a corneal topographer.
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When a developer looks at a parcel of land they purchase, they take a topographic measurement of the land.
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They can tell where the land is steep and where it is flat to understand how to level the ground to build a house.
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A corneal topographic map shows us where your cornea is steep and where it is flat, and it allows us to measure how steep and how flat that cornea landscape is.
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So if the cornea and lens bend the light too much, it comes together as a point in front of the retina.
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But we see cases of myopia, even when the cornea and lens are average in their ability to refract light.
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How can that be?
00:12:09.279 --> 00:12:12.879
Well, you can get myopia if the eye is too long.
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If the eye is super long, the refracted light will have to travel a very far distance to reach the retina.
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If the cornea and lens only bend that light an average amount, it will run out of steam before it can travel this whole length.
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We can measure the length of the eye using a machine in our office called a biometer.
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We can also use an ultrasound machine to do the same thing.
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So we can tell if you have an average length eye, short eye, or long eye.
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If you have a combination of a long eye with a steep cornea, you are likely pretty darn nearsighted.
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Your prescription may be a minus 11 or a minus 15 or a minus 20.
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Hyperopia.
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Now let's talk about the opposite scenario.
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Hyperopia is our second refractive error, and in layman's terms, we call this being far-sighted.
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This means a person can see far away without glasses, but they cannot read or see up close.
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Hyperopic patients have a plus in their prescription.
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Just like myopia, there are different levels of severity of hyperopia.
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Someone can be a mild hyperope with only a plus one in their prescription.
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They can likely read a book on their Kindle if they enlarge the font.
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Or someone might be a plus five diopter hyperope, in which case there is simply no way they can read anything arm's length in without reading glasses.
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In hyperopia, the combined cornea and lens are not powerful enough.
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When light rays pass through these structures, they do not get bent enough.
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This means they end up coming together at a point behind the retina.
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When they hit the retina, just like in myopia, they are scattered, creating a blurry image.
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In hyperopia, the cornea can be too flat.
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Think about someone pushing their finger on the top of Epcot center and smushing it down.
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A flat cornea cannot bend light rays very well.
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Just like in myopia, a hyperobe can have a cornea that is not too flat, just average steepness.
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In this case, the eye is too short.
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Imagine a cornea and a lens that bend light, an average amount.
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That light then travels through the vitreous and would come to a point right on the retina.
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But the eye is short, and so the light rays hit the retina way sooner than expected.
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If a patient has both a flat cornea and a short eye, they are probably quite hyperopic or far-sighted.
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They likely have a pretty big plus in their glasses prescription.
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Astigmatism.
00:14:58.480 --> 00:15:04.799
Now, for a refractive error that really bugs a person, we will talk about astigmatism.
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With astigmatism, the cornea or the lens, or both, are not round and smooth.
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They are lumpy, bumpy.
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So when light rays pass through this lumpy, bumpy cornea, they get bent at all different angles.
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To understand this, think of a ray of light that passes through a cornea normally.
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The rays on the outside of the cornea should get bent more than the rays on the inside of the beam of light.
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The light rays at the very center should not get bent at all.
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They should go straight through.
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If the outer rays don't get bent more than the inner rays, the light beam has no chance of coming together at the same time into one fine point.
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In astigmatism, thanks to the lumpy, bumpy cornea, this does not happen.
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The rays of light on the outside might hit a bump and get bent less than the rays of light on the inside that hit a lump.
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With the rays going all different directions, they can never hit the retina at the same point at the same time.
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It does not matter how long or how short the eye is.
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What does a glasses prescription with astigmatism look like?
00:16:12.879 --> 00:16:16.960
Well, there are actually three parts to a glasses prescription.
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If you or someone you know wears glasses, take a look at theirs.
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The first number in the prescription refers to myopia or hyperopia.
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Do the light rays come together as a point in front of the retina or behind the retina?
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This first number is called a sphere.
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The second number in the prescription is called the cylinder.
00:16:37.840 --> 00:16:41.519
And this number refers exclusively to astigmatism.
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If you do not have astigmatism, your prescription will only have one number to it.
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If your prescription has three numbers, you know you have astigmatism.
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What's the third number for?
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It helps us understand where your cornea is lumpy or steep.
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Astigmatism is really annoying because images are blurry no matter where you look.
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In the distance or up close.
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There's really no good area of vision, no sweet spot.
00:17:12.720 --> 00:17:14.400
Presbyopia.
00:17:16.160 --> 00:17:24.160
Presbyopia is a humbling refractive error because it's the one that lets you know you are officially getting old.
00:17:24.480 --> 00:17:30.400
Presbyopia is when we are no longer able to see up close without the help of reading glasses.
00:17:30.720 --> 00:17:36.000
This happens because we lose our ability to accommodate after the age of 40.
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Accommodation means the ability to shift your vision from distance to near and back to distance again.
00:17:42.720 --> 00:17:44.720
Think about playing a game of tennis.
00:17:44.880 --> 00:17:49.759
Your opponent serves the ball and you watch the ball go over the net and come towards you.
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You watch that ball as you hit it with your tennis racket and then watch it sail away.
00:17:54.799 --> 00:17:59.599
You are able to accommodate thanks to the flexibility of the lens in the front of your eye.
00:17:59.839 --> 00:18:04.799
Remember, that's your second refracting structure, located just behind your pupil.
00:18:05.039 --> 00:18:14.559
Muscles in your eye push and pull the lens to change its shape from fat to skinny, and this changes how powerfully light is bent.
00:18:14.799 --> 00:18:18.400
Remember that imaginary eyeball I made you conjure up before?
00:18:18.640 --> 00:18:25.039
The light rays enter the eye as parallel beams of light and then get bent by the cornea and lens.
00:18:25.279 --> 00:18:28.000
This is true for objects that are in the distance.
00:18:28.240 --> 00:18:33.039
But when the object is close to the eye, light rays come off the object like a funnel.
00:18:33.279 --> 00:18:39.440
They are divergent or spreading out when they hit the cornea as opposed to coming in parallel.
00:18:39.759 --> 00:18:44.720
So they need to be bent even more to get to one single point on the retina.
00:18:44.960 --> 00:18:50.079
The lens goes from skinny to fat, so it has more power to bend the light more.
00:18:50.480 --> 00:18:51.519
Pretty neat, huh?
00:18:52.160 --> 00:18:55.359
The problem arises when the lens begins to harden.
00:18:55.599 --> 00:19:01.279
Then it can no longer go from fat to skinny to fat to change its refracting power.
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This unfortunately occurs for every single human being starting at the age of 40.
00:19:06.880 --> 00:19:07.680
That's right.
00:19:08.079 --> 00:19:08.960
All of us.
00:19:10.240 --> 00:19:11.839
Every single one.
00:19:12.480 --> 00:19:14.960
It's what I've tried to explain to my six-year-old.
00:19:15.119 --> 00:19:31.680
Every time she shoves her art project four inches in front of my face and says, Mama, look, see, I have to gently scoot her arm back, and I'm noticing with each year that passes, I have to scoot it back farther and farther and farther.
00:19:31.920 --> 00:19:38.240
I'm still fine in the distance, but I can no longer shift my focus to see closer in.
00:19:41.279 --> 00:19:42.480
Diagnosis.
00:19:44.960 --> 00:19:51.039
I used to be famous for one of my party tricks back before I started going to bed at 9 p.m.
00:19:51.440 --> 00:19:59.920
Anyone at the party who was wearing glasses would come see me, and I could guess their prescription simply by looking at the way their face looked through their glasses.
00:20:00.160 --> 00:20:02.960
And I guessed it right every time.
00:20:03.279 --> 00:20:05.119
I mean every time.
00:20:05.359 --> 00:20:10.640
This is because glasses for myopia or nearsightedness are concave lenses.
00:20:10.880 --> 00:20:13.839
Okay, talk about going back to fifth grade math.
00:20:14.079 --> 00:20:17.200
Let's dust off that shelf in our brains for a second.
00:20:17.519 --> 00:20:23.759
Concave lenses, if you will remember, are lenses that are skinny in the middle and thick on the edges.
00:20:24.079 --> 00:20:28.880
Convex lenses, on the other hand, are fat in the middle and skinny on the edge.
00:20:29.119 --> 00:20:32.640
To correct myopia, we have to use a concave lens.
00:20:32.799 --> 00:20:36.079
The skinny in the center lens minimizes objects.
00:20:36.319 --> 00:20:42.799
This is true for the person wearing the glasses as well as the person looking at someone's face through their glasses.
00:20:42.960 --> 00:20:49.200
So the edge of their face where their glasses fall will suddenly jump inwards and their eyes will look small.
00:20:49.359 --> 00:20:54.720
If you see someone with a very high myopic prescription, their eyes might look tiny.
00:20:54.960 --> 00:21:00.960
Hyperopic glasses, on the other hand, are corrected with convex lenses that are fat in the middle.
00:21:01.119 --> 00:21:03.279
This will make objects look larger.
00:21:03.440 --> 00:21:10.240
I call these glasses anime glasses because they give someone really large eyes relative to the rest of their face.
00:21:10.480 --> 00:21:20.079
If you've ever watched the show AP Bio on TV, you'll immediately notice one of the students, Heather, has a very high hyperopic prescription.
00:21:20.319 --> 00:21:24.079
Her glasses look like she's looking through the bottom of Coke bottles.
00:21:24.319 --> 00:21:32.400
Before 1949, we used to do cataract surgery by removing a patient's cataract, but we did not replace it with an artificial lens.
00:21:32.640 --> 00:21:33.279
Why?
00:21:33.519 --> 00:21:35.839
Well, they hadn't been developed yet.
00:21:36.079 --> 00:21:40.880
So everyone was left aphaic, meaning with no lens.
00:21:41.200 --> 00:21:44.799
So one half the eyes powerhouse refractor was gone.
00:21:45.039 --> 00:21:53.279
Most folks needed a very high plus lens around a plus 11 diopter lens in order to be able to see.
00:21:53.519 --> 00:21:58.160
It was pretty easy then to spot those people who had had cataract surgery.
00:21:58.400 --> 00:22:11.279
Thankfully, these days, We do put artificial lenses back in the eye after we remove a cataract, and those artificial lenses come with all different powers to match the needs of that particular eye.
00:22:11.519 --> 00:22:17.279
These days, we can get patients out of glasses they have used for years with cataract surgery.
00:22:17.519 --> 00:22:21.839
To diagnose your refractive error, you would want to see your local eye doctor.
00:22:22.000 --> 00:22:28.640
They will likely put you in a machine called an autorefractor that will give a starting point for your prescription.
00:22:28.880 --> 00:22:33.440
This prescription will then be fine-tuned with a manifest refraction.
00:22:33.680 --> 00:22:37.279
This is where you do the better one or better two test.
00:22:37.519 --> 00:22:41.759
As someone with a high prescription myself, I hate this test.
00:22:42.000 --> 00:22:48.400
Every time I take it, I think of that song, under pressure, coming down on me.
00:22:48.720 --> 00:22:57.920
But then I take a deep breath and remember, true eye professionals get a good gestalt of what a person actually needs by the way they answer.
00:22:58.160 --> 00:23:02.799
They know when I am being greedy for more prescription than what I actually need.
00:23:03.039 --> 00:23:06.000
Something common in us myopes, by the way.
00:23:06.240 --> 00:23:15.920
It's always a great idea to bring your glasses in to every eye appointment because we won't know if you need a change in your glasses unless we know what's in your current glasses.
00:23:16.160 --> 00:23:24.720
Like fortune tellers, we can take your glasses and put them in a machine called a lensometer and read the actual prescription in them.
00:23:24.960 --> 00:23:32.000
I once had a patient ask me to be careful not to shake his glasses too much or some of his prescription might fall out.
00:23:32.319 --> 00:23:40.319
Fortunately, as we know now, this prescription is not a magic liquid, but rather based on the shape of the lens.
00:23:40.559 --> 00:23:50.240
Still, I was exceedingly gentle with my patient's glasses because when you are blind as a bat, glasses are magical after all.
00:23:52.720 --> 00:23:53.680
Treatment.
00:23:56.240 --> 00:24:00.319
So now that we know what a refractive error is, how do we treat it?
00:24:00.559 --> 00:24:09.599
In medicine, we like to categorize things from least invasive to most invasive, and we will do the same with treatment options for refractive errors.
00:24:09.839 --> 00:24:12.799
So let's begin with good old glasses.
00:24:13.039 --> 00:24:20.480
These can treat every type of refractive error, including astigmatism treatments and presbyopia treatments.
00:24:20.720 --> 00:24:28.880
Have you ever gotten a glass's prescription from your eye doctor and felt like you were in algebra looking at a boggle of numbers that made no sense?
00:24:29.119 --> 00:24:34.240
Well, after today, a glass's prescription won't look like hieroglyphics anymore.
00:24:34.480 --> 00:24:37.599
The first number in your glasses prescription is your sphere.
00:24:37.839 --> 00:24:43.519
This will tell if you are nearsighted or myopic or far-sighted, hyperopic.
00:24:43.759 --> 00:24:50.720
If you are myopic, this number will have a minus in front of it, and if you are far sighted, it will have a plus in front of it.
00:24:50.960 --> 00:24:58.960
An easy way to remember this is to think about the phrase, he is thinking myopically, which means to think short-sightedly.
00:24:59.200 --> 00:25:00.720
This is not a compliment.
00:25:00.880 --> 00:25:04.400
It's usually a criticism, so it's a minus.
00:25:04.799 --> 00:25:10.880
Some people only have one number in their prescriptions, which means these lucky ducks do not have astigmatism.
00:25:11.039 --> 00:25:16.160
If you have a second and a third number in your prescription, it means you do have astigmatism.
00:25:16.400 --> 00:25:19.839
Remember, astigmatism means the cornea is lumpy bumpy.
00:25:20.000 --> 00:25:22.640
There are steep parts and there are flat parts.
00:25:22.880 --> 00:25:32.799
The second number tells us how much astigmatism you have, how wonky shaped is your eye, and the third number tells us where the steep and the flat areas are.
00:25:33.039 --> 00:25:47.920
If you look at the eye and imagine it is a clock, 3 o'clock is what we call zero degrees, and 9 o'clock is 180 degrees, 12 o'clock is 90 degrees, and 6 o'clock is 270 degrees.
00:25:48.160 --> 00:26:04.240
So if my prescription had a plus 0.5 as the second number and an X90 as the third number, it would mean my cornea was flat at 90 degrees and steep at 180 degrees.
00:26:04.480 --> 00:26:11.440
Some four opters are calibrated for plus cylinder and some four opters are calibrated for minus cylinder.
00:26:11.599 --> 00:26:14.000
Why are they not all calibrated the same?
00:26:14.319 --> 00:26:16.960
That would simply be too easy, folks.
00:26:17.200 --> 00:26:26.240
We measure astigmatism in diopters, and we human beings can tolerate up to 0.7 diopters of astigmatism without being bothered.
00:26:26.480 --> 00:26:34.079
For example, I have 0.75 diopters of astigmatism in my left eye, I don't even bother correcting.
00:26:34.400 --> 00:26:39.839
We consider 0 to 1.5 diopters of astigmatism to be mild.
00:26:40.079 --> 00:26:49.359
1.5 diopters to 3 diopters is considered moderate, and anything over 3 diopters is considered significant astigmatism.
00:26:49.759 --> 00:26:59.039
If you see the words add at the end of the prescription and then a fourth number, it means you have an extra reading prescription in your glasses.
00:26:59.279 --> 00:27:03.279
The higher this fourth number, the closer you have to hold things to read.
00:27:03.440 --> 00:27:10.480
So if you were looking at your computer 20 inches away, you might need a plus 1.25 add.
00:27:10.960 --> 00:27:17.599
But if you are holding a book 14 inches from your face, you might need a plus 2.5 reading edition.
00:27:17.920 --> 00:27:23.440
Patients ask me all the time what prescription they should get for their over-the-counter reading glasses.
00:27:23.599 --> 00:27:30.160
And much to their chagrin, my answer is always, it depends, because it does.
00:27:30.400 --> 00:27:34.319
It depends on how far away they want to be from whatever they are looking at.
00:27:34.480 --> 00:27:45.519
So I suggest they go to the store and pick a magazine off the shelf and pull out their iPhone and then hold that magazine or phone where they want to hold it, not where they can currently see it.
00:27:45.680 --> 00:28:00.640
Then I instruct them to try different reading glasses, maybe a plus 1.5, and if it's not clear, try going up to a plus 1.75, then a plus two until they find the glasses that work for their working distance.
00:28:01.119 --> 00:28:06.400
So, bifocals or progressives, which one should you choose?
00:28:06.640 --> 00:28:10.400
Well, there are advantages and disadvantages to each option.
00:28:10.559 --> 00:28:17.039
With bifocals, there is a line in the glasses that demarcates the distance from the reading prescription.
00:28:17.200 --> 00:28:21.119
It's really easy to find where each portion of the glasses is.
00:28:21.599 --> 00:28:30.640
But many of my patients feel like this line in the glasses is basically a giant neon sign saying, I'm old, I need reading glasses.
00:28:30.960 --> 00:28:36.240
Progressives, on the other hand, have no line, so you can still look young and fresh.
00:28:36.559 --> 00:28:46.160
In these glasses, the prescription gradually transitions from distance at the top to intermediate somewhere in the middle to the reading prescription at the bottom.
00:28:46.480 --> 00:28:54.000
You definitely want to get progressives made at a reputable place so the transition can be as smooth as possible.
00:28:54.240 --> 00:28:58.880
These glasses are great for the person that does a lot of intermediate things.
00:28:59.039 --> 00:29:01.839
Think desktop, computer, or gardening.
00:29:02.079 --> 00:29:05.359
And also a lot of near things closer to their face.
00:29:05.599 --> 00:29:09.440
Think woodworking or sewing or reading at 14 inches.
00:29:09.759 --> 00:29:14.160
Progressives can give this patient the multiple different optical zones they need.
00:29:14.400 --> 00:29:23.440
However, patients can sometimes complain of not being able to find the sweet spot in these lenses because of the multiple optical zones.
00:29:23.680 --> 00:29:33.359
If you do get progressives, I would recommend making sure you get large enough glasses to fit everything in easily, meaning the lenses should be nice and tall.
00:29:33.519 --> 00:29:38.720
Think Velma from Scooby-Doo as opposed to piano teacher glasses.
00:29:39.519 --> 00:29:42.640
Treatment contact lenses.
00:29:44.319 --> 00:29:45.839
Glasses are easy.
00:29:46.000 --> 00:29:47.759
They are also fashionable.
00:29:47.920 --> 00:29:52.960
And as many of my patients point out, they can cover the bags under your eyes.
00:29:53.200 --> 00:29:55.440
So why not just stick with glasses?
00:29:55.680 --> 00:29:59.839
Well, the issue comes when your prescription starts getting large.
00:30:00.079 --> 00:30:07.440
Because of the shape of the lens, glasses for myopia will minimize objects, making them smaller than they appear.
00:30:07.680 --> 00:30:15.680
When you have a prescription like me, I'm a minus 7.5, this can create vision that is just a little off.
00:30:15.920 --> 00:30:19.680
If you are far-sighted with a high prescription, things are magnified.
00:30:19.920 --> 00:30:24.319
If you have a reading ad in your glasses, things get magnified even more.
00:30:24.720 --> 00:30:30.400
Think about if your prescription is a plus four, and then we have a plus two reading ad.
00:30:30.640 --> 00:30:39.920
That means the reading portion of the glasses is a plus six, and that is a huge magnifier that will also create visual distortions.
00:30:40.160 --> 00:30:41.920
These glasses will be heavy.
00:30:42.079 --> 00:30:45.119
Mine give me a headache after a full day of wear.
00:30:45.359 --> 00:30:48.319
And they can really reduce peripheral vision.
00:30:48.480 --> 00:30:53.200
Not really a great idea when you are, oh, for example, driving.
00:30:53.759 --> 00:31:01.119
And when you are running or in a downward dog, it is really not fun to keep pushing these glasses back up your nose.
00:31:01.359 --> 00:31:07.200
It doesn't happen often, but imagine if you have a different prescription in one eye versus the other.
00:31:07.440 --> 00:31:15.839
If you are nearsighted in one eye and then far-sighted in the other, well, objects will be smaller in one eye and larger in the other.
00:31:16.079 --> 00:31:29.440
This is called anisaconia, and it makes for some really uncomfortable vision as your brain tries to mesh these two slightly different sized images together into one coherent image.
00:31:29.759 --> 00:31:32.960
These reasons are why contacts were created.
00:31:33.119 --> 00:31:35.359
Contact lenses are amazing.
00:31:35.519 --> 00:31:38.480
I've been wearing mine since I was 10 years old.
00:31:38.799 --> 00:31:48.640
However, it is critical, and I mean really critical, to only choose this option if you are committed to practicing good contact lens hygiene.
00:31:48.880 --> 00:31:53.119
This means always washing your hands when handling contacts.
00:31:53.359 --> 00:32:02.079
Never, ever, like ever, sleeping in them overnight or storing them in anything other than proper contact lens solution.
00:32:02.400 --> 00:32:07.599
No tap water or I shudder as I say this, spit.
00:32:08.000 --> 00:32:08.640
Yuck.
00:32:09.200 --> 00:32:17.279
Also, not using your contacts longer than they were intended to be used and always giving yourself a contact lens holiday.
00:32:17.519 --> 00:32:27.839
No, this does not mean we ship our contacts to Hawaii for a vacation, but rather that we take one day a week to not wear our contacts so our eyes have a chance to breathe.
00:32:28.079 --> 00:32:38.319
Here's a fun fact: the closer a person's prescription is corrected to their retina, remember that's the tissue that plasters the back wall of the eye, the sharper that vision is.
00:32:38.559 --> 00:32:45.519
Glasses sit an inch or so away from the front of your actual eyeball while contacts sit on your actual eyeball.
00:32:45.759 --> 00:32:48.319
So contacts will give you clearer vision.
00:32:48.559 --> 00:32:56.319
Contacts don't change the size of images, so they are great if you have a high prescription or a different prescription in each eye.
00:32:56.559 --> 00:33:00.319
These days, contacts can correct quite a bit of astigmatism.
00:33:00.559 --> 00:33:03.519
These contacts are called toric contacts.
00:33:03.680 --> 00:33:06.720
These days, contacts even have a reading prescription in them.
00:33:06.880 --> 00:33:07.680
It's true.
00:33:07.920 --> 00:33:15.920
These contacts are called multifocal contacts, and they come with low or high reading powers depending on how close you like to hold things.
00:33:16.079 --> 00:33:17.359
Do they really work?
00:33:17.759 --> 00:33:22.960
Well, not for everyone, but if you are able to tolerate them, they are pretty neat.
00:33:23.200 --> 00:33:30.319
One night I wore a multifocal contact lens in one eye and a regular distance-only contact lens in my other eye.
00:33:30.480 --> 00:33:36.319
I was able to read my menu with a multifocal contact eye, but with the other, no way.
00:33:36.799 --> 00:33:38.640
Everything was blurry.
00:33:38.960 --> 00:33:43.839
The other neat thing about contacts is you can try something called monovision.
00:33:44.160 --> 00:33:48.079
This is where we correct one eye for distance and the other eye for reading.
00:33:48.240 --> 00:33:52.240
Then both eyes work together to give you a range of vision in between.
00:33:52.480 --> 00:33:56.240
Word of warning: not everyone can tolerate monovision.
00:33:56.480 --> 00:34:02.079
I put both my parents in monovision contacts in preparation for eventual cataract surgery.
00:34:02.319 --> 00:34:05.200
My mom took to it like a fish in water.
00:34:05.519 --> 00:34:08.159
My dad hated it from the get.
00:34:08.480 --> 00:34:12.239
He was like, wait, why did I pay for your med school?
00:34:12.480 --> 00:34:16.239
Some brains just don't like dissociated vision.
00:34:16.480 --> 00:34:29.599
When we make one eye for distance and one eye for near, we take away your depth perception, and this can really bother some folks, while others' brains will use extra visual cues to make up for this lack of depth perception.
00:34:29.760 --> 00:34:33.599
But if you're a tennis player, monovision may not be right for you.
00:34:33.840 --> 00:34:43.920
If you have a corneal scar or a significant amount of astigmatism, think over three diopters, then you might really benefit from hard contact lenses.
00:34:44.079 --> 00:34:47.119
We call them gas permeable lenses.
00:34:47.360 --> 00:34:55.360
Because they are a hard shell, they will force a really wonky cornea into as round and smooth a shape as it can possibly get into.
00:34:55.760 --> 00:34:59.039
Hard contact lenses make some people shudder.
00:34:59.199 --> 00:35:02.719
The ones from the 80s and 90s make me shudder.
00:35:02.880 --> 00:35:09.599
However, technology has changed and hard contact lenses are much, much easier to tolerate these days.
00:35:09.840 --> 00:35:13.519
Some people even prefer them to soft contacts.
00:35:14.960 --> 00:35:18.000
Treatment, artificial lenses.
00:35:19.679 --> 00:35:24.000
Could we get even closer to the retina than contact lenses?
00:35:24.239 --> 00:35:25.760
Why, yes, we can.
00:35:25.920 --> 00:35:30.079
We can put the correction for your refractive error right into your eye.
00:35:30.320 --> 00:35:36.239
We do this during cataract surgery after we remove your clouded natural lens or cataract.
00:35:36.400 --> 00:35:44.079
Light contacts, artificial lenses come with astigmatism correction and can have a reading prescription built into them.
00:35:44.320 --> 00:35:49.119
For more information, listen to the podcast on artificial lenses.
00:35:49.440 --> 00:35:52.960
Can we correct your prescription right up next to the retina?
00:35:53.519 --> 00:35:54.559
No, not yet.
00:35:54.800 --> 00:35:55.760
But you never know.
00:35:56.000 --> 00:35:59.119
Technology is advancing every day.
00:36:01.199 --> 00:36:02.719
Conclusion.
00:36:04.960 --> 00:36:10.960
I did a medical mission trip to Nicaragua with one of my partners when I first started at my practice.
00:36:11.199 --> 00:36:17.599
I had done medical mission trips before to Haiti, but this was the first one in my specific field of ophthalmology.
00:36:17.840 --> 00:36:22.320
As a doctor, it was hands down the best week of my life.
00:36:22.559 --> 00:36:23.119
Why?
00:36:23.360 --> 00:36:28.159
We went into a village and set up a rudimentary clinic in any available building.
00:36:28.320 --> 00:36:31.199
It was nearing 100 degrees without air conditioning.
00:36:31.360 --> 00:36:33.039
No patient had insurance.
00:36:33.280 --> 00:36:39.760
There was no such thing as prior authorizations, no electronic medical records, no pharmacies to shop out.
00:36:40.000 --> 00:36:42.719
We came with whatever treatments we could dispense.
00:36:42.880 --> 00:36:47.119
This was mostly in the form of glasses, though we did have some drops with us.
00:36:47.360 --> 00:36:51.440
These glasses were donated by people who no longer needed them in the U.S.
00:36:51.840 --> 00:36:57.440
Some pairs were Gucci and Prada, and some looks like they were created in the 60s.
00:36:57.599 --> 00:37:01.840
We had a simple check-in table where volunteers would get a brief history and vision.
00:37:02.000 --> 00:37:04.400
The patients then came to my partner and I.
00:37:04.559 --> 00:37:10.800
We didn't have any fancy machines, just the absolute basic handheld equipment you could think of.
00:37:11.039 --> 00:37:18.559
We figured out our patient's problem and then gave them glasses or advised them to go to the nearest medical center six villages over.
00:37:18.800 --> 00:37:21.840
No credit cards were accepted, no billing was sent out.
00:37:22.000 --> 00:37:28.559
My office manager never gave me that look that tells me I'm running two hours behind, so need to stop talking so much.
00:37:29.039 --> 00:37:32.639
I'll never forget an old man who entered our clinic.
00:37:32.880 --> 00:37:39.360
He was a very thin but wiry man who had ridden his bicycle 50 miles to reach our clinic.
00:37:39.679 --> 00:37:40.800
Barefoot.
00:37:41.119 --> 00:37:43.760
He had left at four in the morning.
00:37:43.920 --> 00:37:51.920
He could not speak any English, but communicated with the biggest smile that showed off his remaining two or three teeth.
00:37:52.159 --> 00:37:56.239
The phrase blind as a bat could have been written for him.
00:37:56.480 --> 00:37:59.280
He could not make anything out on the eye chart.
00:37:59.440 --> 00:38:03.360
It turns out he had had cataract surgery with a medical team.
00:38:03.599 --> 00:38:08.320
They couldn't put a new artificial lens in his eye and didn't have any glasses for him.
00:38:08.480 --> 00:38:14.480
His cataract had been huge, so his vision was better than it had been, but not much better.
00:38:14.719 --> 00:38:18.719
His prescription without an artificial lens was a plus eight.
00:38:18.880 --> 00:38:21.119
That's a very large prescription.
00:38:21.360 --> 00:38:25.760
We dug in our bag, and lo and behold, we had a pair of glasses.
00:38:26.000 --> 00:38:30.400
Only one pair, mind you, with his exact prescription.
00:38:30.639 --> 00:38:37.760
We put it on his face, and it was like watching one of those videos where a baby sees his mother's face for the first time.
00:38:38.079 --> 00:38:40.639
It was revelatory.
00:38:41.039 --> 00:38:42.800
Game changing.
00:38:43.199 --> 00:38:47.760
Now, along with his big, non-toothy grin, were tears.
00:38:48.159 --> 00:38:49.679
A stream of them.
00:38:49.920 --> 00:38:52.639
When he left our clinic, we all got hugs.
00:38:52.800 --> 00:38:55.760
He walked out of the clinic with so much confidence.
00:38:55.920 --> 00:39:02.159
Right as he got to the threshold, he jumped in the air and clicked his bare heels to one side, then the other.
00:39:02.400 --> 00:39:07.280
It's a moment that is imprinted in my brain.
00:39:07.519 --> 00:39:19.840
Each day I do fancy surgeries and use cutting-edge technology, but I try never to forget that sometimes the simplest of treatments can be life-changing.
00:39:20.320 --> 00:39:24.480
Until next time, see well and be well.
00:39:48.800 --> 00:39:52.239
Then why do you always tell me that it's really gross?
00:40:04.800 --> 00:40:06.239
Creepy for me.
00:40:07.519 --> 00:40:11.360
Okay, well, you have plenty of time to change your mind.
00:40:11.679 --> 00:40:12.559
Thank you.
