TechStuff Classic: TechStuff Stares at Laser Eye Surgery

means it's Friday. Today. We're gonna look at an episode that originally published on October twenty four, two thousand eleven. Chris Pallette and I talked about laser eye surgery. I found it fascinating. Chris turned about eighteen shades of green while we recorded this. It's been a long time since I've seen Mr Pillette, but I remember how green he turned when we talked about the process. I have had laser eye surgery done, and now I'm essentially a super human.

I can see through walls and shoot lasers with my eyes. Maybe, I guess we'll find out. Let's listen in on this classic episode today. We're going to talk about laser eye surgery. We've had some people ask us about laser eye surgery and what goes into it and exactly how are lasers used in the process. But I think that's a record for your use of that version of lasers. Yeah, And so we're going to, uh, we're gonna kind of break it down and talk about what goes into a laser

eye surgery procedure. And we should also mention I should mention that I am very close to someone who has had laser eye surgery, not right now, not like physically. I was going to my wife. My wife had laser eye surgery, um, and she has been very happily moving around without the need for glasses for several years now, um. And it was very impressive to me because my wife is not the the person who typically likes people, uh,

you know, messing with eyeballs exactly. Yeah, She's it's not high on our list of things to do today, but she did it anyway. And we're going to kind of talk about the process and what you have to do in order to get laser eye surgery and what's actually being done to you. Yeah. And I think probably the best place to start is speaking of eyeballs with the eyeball itself. Yeah, and why you might need laser eye

surgery in the first place. Right, Uh, to to to understand this discussion, you have to have at least a basic geography of the eyeball. So let's talk a little bit about the eye. So, so your your eye. The outer coating is this sort of tough outer coating called the sclera, and that's sort of what keeps the eyeball in its shape. It's it's kind of the the well,

it's just it's the outer layer. And then part of this outer layer, about I think one sixth of it is the cornea, which is the clear outer layer that goes or the part of your eye where light actually passes through to get to you know, your eyeball. Right, So the cornea is, uh, it's kind of like a window in a way, or if you want to think of it like a a tablet device or something. It's the gorilla glass. It's on the outside that protects the

the the innards. And then behind the cornea, well, first of all, you've got this sort of a watery clear liquid called the aqueous humor. Yeah, this goes back to the old humors. UH idea that dates back centuries where we used to think that our bodies we were like we're governed by a well, a small group of various liquids called humors. We've somewhat developed beyond that at this point, although I do think it's it's funny that even now we are referring to this particular liquid as a humor. Yes,

so so the queens humor. It's it's this clear, clear liquid that's behind the cornea. It's also in front of the iris, and there's a little bit behind the iris as well. So then that leads to the question, what then is the iris. Well, that's the that's the color part of your eye. So for example, my iris is blue because it lacks a certain amount of pigmentation which makes it a blue color. My wife's eyes are brown. And uh, this is the part of the other acts

is like an adjustable diaphragm around the pupil. So the pupil is the that's the dark center of your iris. That's the little opening actually that allows light to pass through, right, And of course that's the part that the UH enlarges or gets smaller depending on the amount of light in the room. Yeah, it's it's it's really an ingenious kind of approach. Really, it's it's the same sort of thing that we do with cameras when we have an aperture,

you know, the aperture of a camera. And you may remember this if you us into our our podcast about slow motion, we talked about the aperture quite a bit. Uh. That's what allows you to adjust how much light comes in through the camera's lens and hits the sensor. Uh, same sort of idea here. The iris is what will expand or contract around the pupil and thus control the

amount of light that comes in. So, if you walk into a dark room, then the it's going to the the iris is going to allow more light to pass through. It's gonna allow more of the pupil to be exposed so that you get more light so that you can maneuver through because you know you're gonna be able to you need to be able to see if you're in a really bright environment. In order to protect the eye, the diaphragm is gonna close around the pupil to restrict

the amount of light that comes in. Right, And of course, um there there's more than one um analog as far as the eye and a camera. Sure, we were talking about cameras not too long ago, where we we talked about the lens and how light passes through the lens to the film on the other side, or or an

image sensor in the case of a digital camera. Well, in the eye, you've got the retina, which is um if you will, on the on the back side of the eye, which is what records the image as as the light comes through the pupil right you've got You've got the pupil, that's the aperture. You also have a lens right behind the pupil, So the lens, the lens is what is focusing that light, directing that light so that it it hits the focal point ideally, which is

the retina. And the retina contains certain kinds of cells, rod cells and cone cells. These are light censoring light sensors. Essentially, UM he sells sense the presence of light and UH through a chemical reactions send that information to your brain and then your brain says, hey, I recognize that that's a puppy. Also, at the interesting point, if you weren't familiar with us, UH, the image that you see when you're looking at something. When it hits your retina, it's

actually inverted, just as it is in a camera. But yes, that's the So this, this is the basic part of the eye. Now, what happens when something is just not quite right? For example, Uh, Chris, I don't know, are you near sighted or far sighted? I am myopic. I am also myopic. That means we are both near sighted, and since we both have our our glasses off at the moment, we're both a little blurry. So myopia means that the focal point is hitting. Uh, it's it's hitting

before it gets to your retina. So inside your eye there's a you know, the light is being directed by the lens to your retina. Uh, those the points of light are all converging, right, and that point of convergence is the focal point. Now, the focal point for those with myopia is in front of the retina. It's not hitting the retina just right. So that means that when we start looking around things, things tend to be the further way things are, the blurrier they tend to be. Yes. Um, Now,

this can happen through various uh, just well irregularities. There could be irregularities in the cornea that can cause this to happen, or in the lens itself, or it could be that the eyeball itself is elongated. Yes, so that the you know, if the eyeball was not elongated, the focal point would be right there on the retina where it's supposed to be and everything will be fine, but

the eyeball has been stretched. Nice sound effect. Thank you doesn't necessarily doesn't necessarily mean that someone's actually gone in there and stretch your eyeball. It just means that that's kind of the way it developed. Um now far sighting this which is a hyperopia hyperopia, thank you, I'm glad you're ready for that one. Ready, Yeah, hyperopia. You've got the focal point that's that's actually behind the retina, so when the lights hitting hitting the retina, it's not converged

on that point like it should be. And U hyperopia, If you're hyper hyperopic, would that be correct? Hyperopic? Then that would mean that, you know, you would the the the closer something is, the more out of focus it is, the further away it is, the clearer it is. Also, in addition to being myopic, I also have an astigmatism, I too have an a stigmatism. I think he's just just you know, doesn't want me to have one more

than he does. I only have one. Do you have to well know I'm saying, are you and have an astigmatism? Me too? Me too? Just it happens to anyway, and and an a stigmatism. Um, you have a difference in the shape of your cornea or the lens. And basically what happens is it creates, in effect, two focal points within your eye. Yeah. Um, And so basically that sort of confuses the way the light is travel inside your eye.

And that, um, you can have, as we were both pointing out just a moment ago, you can have, uh, a stigmatism on top of another eye condition. Yes. Yeah, it's really an uneven curvature of the cornea or or lens. And yeah, it's it. It can cause problems. So the thing is that the humans are clever and um, yeah, and we figured out a long time ago that if you use a lens of glass and it's curved just the right way, the curvature of the glass can direct

light so that it corrects for these problems. I can't imagine the amount of trial and error it took to be able to figure this out. But to correct your your vision you have to, you know, take into account what the focal point is doing, uh, inside your eye. So with it's a little bit different between myopia and

and hyperopia. But anyway, the curvature of the lens depends upon the condition, right, you know, if it's gonna be a concave lens for one and a convex lens for the other, And honestly, I can't remember the one from the other. I guess I could stare at my glasses long enough and try and figure it out. But um, but the point being that that's what's going to direct the light the right way into your eye so that

it corrects for whatever problem you already have. Chris and I have more to say about laser eye surgery, but first let's take a quick break to thank our sponsor. What if we didn't want to wear glasses, what if we wanted something where it wasn't you know this this pair of frames sitting on our face. Well that's when we started to come up, well, we could maybe make a lens that could sit directly on the eye and

do the same sort of correction. It's gonna require a more precise approach because it's going to be a much smaller lens that by definition, I mean, you can't have an enormous lens shoved into your eye and expect any sort of comfort. So, um, well that's where the contact lens idea came from, where we started to kind of get you you apply these same kinds of thought to a thin lens that could fit directly on top of the eye. But then we thought, hey, wait a minute,

we're really just talking about lenses here. Even even the cornea can act somewhat as a lens. The cornea on your eye itself directs light. So what if we were to reshape the cornia so that it corrected for whatever problems we had as you know, as far as vision problems are concerned. Uh, what if we just did that, then we wouldn't have to wear contact lenses or glasses or anything. And that's where the idea for corrective surgery

comes from. And um, and at its very most basic level, what correct to what this laser eye surgery is doing is it's altering the shape of the cornea so that directs light in a way that corrects for whatever vision problem you have. That's that's the basic you know, when you get down to it, that's what laser eye surgery is all about. So it's just it's that same principle behind grinding the lens so that you can see, you know, in a pair of eyeglasses, but now it's applied directly

to our biology. It sadly does not mean you will actually end up with laser shooting out of your eyes, well at least not for most people. No, I would think that's a pretty rare side effect. So, yeah, where would you like to start with laser eye surgery. Well, I was going to talk about sort of the process you have to go through before you get laser eye surgery done, and then we'll get into what is actually

going on in a a laser eye surgery session. Yeah, because frankly, it's it's reminds me of a lot of life events. You know. The actual event itself doesn't really take all that long. Laser eye surgery only takes a few minutes. Yeah, it can take less than half an hour total um. But there is quite a bit of preparation that needs that you need to go through beforehand. To make sure that everything goes smoothly, um and preferably not panicky, which is the reason that I haven't had

it done. Yeah, So the first thing you have to do is you have to go through and we're talking about a reputable laser eye surgeon. This is a good time for us to point out there are a lot of different facilities out there that offer laser eye surgery services.

Do your research. Yes, that's a great idea, because I know for a fact that there are there's a few in Atlanta that have a reputation for being less than honesty, Like they'll the what the they do is they'll offer this amazing sounding deal and of course we all know the phrase it sounds too good to be true. It

was probably on the internet. Um, and the deal the deal would be something like two D and I, which is about a tenth of what some eye surgeries cost, you know, and you're thinking, Wow, that's amazing, And then you know it's got an official sounding name and that's

gonna be great. And then if you actually start doing some research, you'll see that there's often a lot of bait and switch involved where you'll go in and they'll do this initial I exam, and then they'll say, oh, well, in your case, because you have this particular you know, condition or whatever, it's actually gonna be closer to hundred per eye or and and just that alone is a you know, first of all, that's kind of a shady

business practice. But beyond that, you don't want you know, you don't know how far their ethics extend into, say, not being a good doctor. So so in other words, do your research quick alert. So assuming that the the facility has got a good reputation, uh, you go in, you would get a very thorough eye exam, probably more thorough in fact, I would are definitely more thorough than you would get going to just get a pair of glasses or contact lenses. I'm sure yes, because they have

to be they have to be very careful. Um, if you're going to go for for lasic, for example, Um, your eyes have to fall within a certain set of parameters, and they can treat myopia, hyperopia and a stigmatism, but it has to be within a certain range. Now, of course that's measured in diopters um. That's that's kind of the degrees of prescription. So you know, if you hear someone say, oh, I've got minus three in this I and minus two point seven five in that I the myopic. Yeah,

their myopic. Yeah that a negative number means myopia, a positive number is hyperopia. And then um, a stigmatism can go either way. Yeah. Now, we we do have a great article on how lasic works on the website. UM and according to the research in there, UM, myopia treatable with lasic can be from negative zero point seven five to negative ten, which is that's a big, big range.

And and I should also add that depending on which doctor you go to, they may tell you that if your eyesight falls within you know, a certain range, like saying, let's say the negative point seven five to say negative one point five, they might say, you know what, the the experience you're going to have, the the new vision you're going to have, may not be so dramatic as to warrant laser eye surgery. Again, a reputable UH clinic is going to tell you if the the result is

going to be truly noticeable or not. For some people it may not be. I for at least years ago, when my wife could have done I was right there on the the border like like you know, I could have gone it done, but it may not have been that dramatic. And when you're talking about that kind of expense, really do you want to go in for that. My wife, however, she had gotten to the point of vision where they no longer use the eye chart. They would say how many fingers am I holding up? So she was an

ideal candidate. Well, you have to hold some up. Um, Like whoa, you need some surgery. Hyperopia that they can treat with lace ranges from plus zero point seven five to plus four and then they can treat a stigmatism for plus or minus zero point seven five to plus or minus four um. So that's a pretty a pretty decent range of vision that they can they can correct. Um. They also look at the cornea thickness. It has to

be five microns or greater um. That's we'll explain why the cornea has to be at least that thick coming up. And that's going to be the the squiggly squirmy part where we're both like, okay, so here's what happens next. I'll be going out for some water, Chris, Chris might might go bye bye for about for about five minutes.

Was that thud? Yeah? But there are other types of laser eye surgery that you can pursue if your cornea is not of that thickness, if it's if it's thinner than that, there are other types of laser eye surgery you can look into, so to speak, right, Um. And then your pupil uh should be no more than six point five millimeters in diameter. Um, although you know there are advances now that allow you to work with up

to eight point five um. Also, so if you' have been Diesel from that that movie where he's got those huge corneas, the huge pupils, that just wouldn't work. Lady Gaga from that that one video, Yeah, there you go. Yeah, those those folks, I'm sorry, or practically any Disney character, because I mean, have you seen Tangled. That girl's eyes are huge. Yeah, Sailor Moon is not gonna have it

done either. Um. So yeah. And also if you're pregnant, have heart problems, severe heart problems anyway, Um, if you're taking drugs such as medicine for migraines or acne, um, you have a condition called kara to countess, I'm hoping I'm pronouncing it right. I didn't check the pronunciation, but

it's a thinning of the cornea condition. And UM, actually I might be Uh, I might not be eligible either because certain conditions like autoimmune diseases one of which I have, UM, vascular disease, different kinds of eye diseases, and diabetes, all these things might prevent you from going through with a lasic procedure. UM. So these are things that the doctor is going to have to talk to you about. UM,

and I would encourage history. Yeah, you need to be honest too, because you know, even though you may not want to wear glasses. Uh, you know, this is serious business and you could end up with results that you are not happy with. It can be complications as well. I mean even yes, you know, it could be that everything goes well, but uh, you have some complications during

the healing process. And if your medical history means that you can't have certain kinds of drugs to to help that healing process along, that could be an even bigger problem down the road. So yeah, it's very important. And then the actual exam, you're going to be looking through lots of different devices that are going to be measuring how your eyes are receiving light. And there's actually technically mapping out your eyes, the inside of your eyes. Um,

there's a thing called a corneal topographer. Yes, that's where they type on your eyes, right, that's a typographer topographer. It actually maps the cornea, so it's it's looking at the actual shape and thickness of the cornea. Um, and it's to uh to really determine exactly how the light

is behaving once it hits that part of your eye. Um. There's also the pupilometer, which is another device that's looking specifically at your pupil I mean, there's not a big surprise there, right, you have a student in your eye, all yeah, and then the their software, very powerful software, but working behind the scenes that's mapping out your eye so that the surgeon is going to know exactly what sort of of adjustments they're going to need to make to your cornea in order for it to um to

direct light the way you need it to be so that you don't have to wear glasses or contact lenses anymore. So it's it's pretty complex stuff. I mean, it's um, pretty fascinating to see. And also a laser eye surgery procedure often requires two people A surgeon and at well beyond the patient to people to actually to do the procedure the surgeon, and then there's usually a an operator

who's working on one of the laser machines. I hate to interrupt while we're strolling down memory lane, but it's time for us to take another quick break to think our sponsor. Now we've talked about the process where let's say that you've gone through you've had your eye exam, you've done your medical history, and they've determined your what is called an ideal candidate. Now, that does not mean you are the perfect person to have had laser eye surgery.

It just means that you fit those parameters that um you don't have anything outlying any of those parameters that would that would cause concern. It appears that it will work out. Yes, Uh, now is the time where you start to um to to actually go through the surgery itself. And I think I think we can walk through the laser process because that's still fairly common. I mean, that's that's actually probably one of the most common forms of laser eye surgery out there. But we'll also talk about

how the other kinds are a little different. So um so, first when you arrive to get your laser eye surgery done, one thing that happens fairly frequently is that they offer you something to calm your nerves. Yes, because it turns out when a lot of people, when they're thinking they're going to be laying down on the table with someone shooting laser beams into their eyes, they get a little anxious. I can't imagine why. Actually, that's not the part that

makes me anxious. But we'll get into at UM. So you know, it's the part immediately before the laser gets shut to your eye. That would be the part. Yeah, that's the part where it gets I'll score me. Yeah, so and yeah. I mean basically, they're going to set up an appointment when you do your your pre op work. I don't think that they actually would take you back immediately and go all right, you look good, let's go. No, No,

it's usually it's usually a day or two between. Speaking from my wife's experience, she went in and had the um the work, that the pre up work done, and then it was a couple of days later after they had a chance to really look at the data and they arranged for the time. And you also have to go there with someone else to drive you home. Yes, because you will not be able to use your eyeballs. Yeah for that, Yeah, exactly, You're you're going to have

some limited eyeball use immediately afterwards. You can't put your weight on them exactly. Um, use some eye crutches. So I crutches? Um are those apple products? Um? No, it's

not the lower case I E I see. Um. So the next thing they're gonna do, once you're you're sure you want to go through this, of course, they also make you sign a waiver saying that you understand that there are things going on where they're gonna shoot lasers in your eyeballs and uh, there are risks involved with that, and part of this depends a lot on your cooperation, like and and not running from the office screaming. Um again,

I'm just imagining what would happened with me. They assuming your your nerves of steel are holding, are holding, they will go ahead and put some topical anesthetic in your eyes. Yes, so this is to numb your eyes because they will need to touch them and uh. And once you're once that started to take effect, you're lead into the upberating

room where you laid down on a table. It's usually a padded table, and they position you so that you're going to be under the machine that goes ping and uh and and then they have to h while they have to secure your eyelids so that you're not going to be blinking, yes, because you cannot blink, so they may be using usually a combination of things. There's usually some sort of tape that's safe to put on your

your eyelids to keep your eyes open. There's also a device that will sit on top of the bottom part and top part of your eyelids to keep those them stationary. Um. This looks a lot like the device that was used in a famous documentary called a clockwork orange. Um. Yeah, it's a little freaky if you're looking at someone who's getting this done. The eyelids speculum. Yeah. Yeah. It's to hold those eyelids in place because of course, if you blink when the laser is going, it's gonna totally mess

up the procedure. So they have to they have to uh stabilize and and keep your eyelids from moving. Um. And they also put down a ring around your eye that that stops you from being able to move your eye around. You're you're looking directly up. Are directly straight straight ahead is the best way of putting it. Not up as in your eyes are turned up, but looking straightforward. It's just because you're laying on your back. It just happens to be up. And then as they the next

step is the squiggly part. Are you ready? Okay, So they pull out the microcarra tome Yes, see they have to. They're gonna put some marks on your cornea to identify where it is green, where they're where they're going to use the microcarra tome um. Basically, when you're dealing with something as sensitive as vision, and you know, the professionals want to do a good job, they're going to want to be as accurate as possible, so they're going to mark your cornea to make sure that they use the

microcarratone right, I don't even want to talk about it. Microcart. It's a surgical instrument, okay. It's a blade, a very thin blade, and this blade is used to cut a flap in your cornia, which is then pulled back so that the laser gets shaped corny. This is this is this is entertaining and painful to watch. This is the part the grosses me out. I'm sorry. Okay, So yeah,

so there's actually this and this is lazing. There are other versions of laser eye surgery that do not use this, and some of them don't even use a microcarratone blade. They have a special laser that will cut this flap. But an end lazing eye surgery, there is a flap that's cut and pulled back so that the laser can start to shape the cornia without that outer layer in place. And UM. And so at this point, the laser, which is um called an well it's an ex semer or x simer E x c I M E R I

actually did not look up the pronunciation. But this is the laser that does the actual shaping. It starts to vaporize parts of the cornea. And what's doing is it's shooting ultraviolet UH blasts and the lasers in the ultraviolet lank range, which means you can't see it right, it's outside the range of human sight. UM. And what it's doing is it's exciting UH the molecules in the cornea to the point where the molecular bonds breakdown. So it's

actually that's what I talk about when vaporizing. It's not heating the eyeball up, especially a cool laser. I expect you to break down. And when I mean cool laser, I don't mean that it's like super awesome, although it is. I mean it doesn't heat up the tissue. Now, remember earlier I mentioned that your cornea has to be five microns are greater when they start this procedure, and that's because when they're done using this laser, there has to

be between two three microns of thickness once they're done. Yeah, so there has to be enough for them to leave the proper amount once they're finished, otherwise you can't do this. So now, now using this laser to vaporize these molecular bonds and to reshape your cornea, that's essentially the same thing on on a grand concept level as grinding a glasses lens. So that's gonna been light the way way.

It's the same things, just we're using lasers and your actual eye to do it, which is pretty phenomenally awesome. It's also kind of scary um not at the end of it. After it might take I don't know seventeen to twenty seconds to do this. Chris's be okay, okay, yeah, per i. Um. They then replace the flap back down on your eye and it heals. I mean, it sets down in place and is is healing as soon as it touches back down. That is one of the very

cool things I think about that. Um. They the doctor will also probably put a little antibiotic on the flap just to make sure that there are no bacteria getting in there. Yeah, but but it maybe it starts to heal, which is pretty phenomenal. Um. The the whole process only takes, like I said, about twenty seconds per eye. Uh. And uh, usually when you're down there, you'll hear people talk about how the doctor told him to look at, say like a blinking red light. That red light is not the laser.

That's just a light that let's Yeah, you're supposed to focus on that while this ultra violet laser is blasting your your cornea way. Um. And then once the flap comes down, you're usually you're given several different kinds of

eye drops before before you leave. Uh, there's a moisturizing eye drop because after you get this process done, your eyes are gonna have a little bit of difficulty, uh, generating the right kind of moisture to keep your eyes comfortable, so you're gonna have to actually add eye drops in on a pre regular basis. In fact, the first couple of days, it's it's like every hour you've got to add eye drops, and then as the time goes on,

you have to use them less and less frequently. And my wife at this point rarely ever uses eye drops. But for the first year she was using them on on a fairly regular basis, although that that schedule changed over time, like after the first three months, it didn't need to be as frequent. Um. And now it's it's rare when she needs them, but occasionally she does. Uh. And then you might also have antibotic eye drops that

you might have to add every now and then. And some places apparently put give you a kind of gel that you put on the inside of your lower eyelids so that when you're asleep, it keeps your eye moisturized while you're sleeping. My wife, I don't remember her getting that. UM. I should have asked her before I left the house this morning, but I do not recall her getting that kind of stuff. I do remember the other kinds of eye drops though. And then they of course schedule, as

you know, a lot of surgical procedures. UM. They also schedule regular appointments, even even as as soon as the next day, to make sure okay, UM. And then gradually as time goes on, uh, you know, they check less frequently. You know, there'll be a year check up, but you know it's one day, and then they'll check the next week and the next month, UM an increasing increasingly longer periods, just to make sure everything is healing the way it's

supposed to. Just to make sure that there are um, that your eyes are doing what they're supposed to do, when you're not suffering any ill effects from the surgery. Because in the case of I mean there there are times when the flap can get a wrinkle in it. Yeah, I was wondering if we're going to get into that. Yeah, that can have things like that that can cause a little bit of blurry vision and may require a second surgical procedure in order to get it straightened out, so

you speak. UM. Also, you know, there's a possibility that they may remove too little or too much of the cornea UM. So they have to be. Yeah, they have to be. That's why they that's why they're doing that whole long pre ops sections, so that they can determine that as precisely as possible to to reduce that risk as much as they can. And of course, again this also depends a lot on the patient. You have to be able to lay there and be still while your eye is being held open and lasers are being shot

into it after someone's kind of flapping it. It's a little it's a bit of a challenge for some of us. Um let's talk really quickly about some of the other kinds of laser ice surgery besides lazing. The one of the the precursors to lazing, and it's still in use in a lot of places is PRK laser ice surgery or photo refractive care TECTO me. Oh, I didn't know

I was gonna be able to say that. In this one, they actually scrape away the outermost layer of the cornea with the laser and then reshape the tissue on the underlying surface of the cornea um and then they have and then you have to allow the the protective layer that was scraped off to grow back, so there's actually a longer healing period with PRK than with laze. They can use that process to uh to work on near sidedness and a stigmatism at the same time, however, which

is nice. Yep. And uh. Then there's lazac with an E. The lasic we're talking about is with an eye, but lazac is a slightly more advanced version of PRK that uses um alcohol and solution to soften and then remove the epithelium, which is that protective layer, that almost layer of the cornium. Yeah, lasac is a laser epithelial caratatamliusis Yeah,

I think I didn't mangle that terribly yep. And then there's epilasac, the modified version of that that uses a separator so that the because then in the traditional laze you're actually removing the epithelium entirely, and epilasic you're creating a separator so that you preserve that epithelium and then replace it on the ice. So it's like you take the cover off, fiddle around a bit, and put the

cover back on. It's probably a bet the eye surgeons out there just love me for saying that um there's l t K or laser thermo keratoplasty. Uh No. It's used mainly for far sightedness and a stigmatism. And in this case they actually are using heat. They're using the heat of a laser beam to shrink and reshape the cornea rather than removing it, so they're actually reshaping it.

They're pushing the stuff around as opposed to cutting it away. Um. And it's supposedly a much faster healing process than most other kinds of corrective surgery, and it's generally considered to be less invasive, so it's uh, that's an interesting approach. There's also there's a custom view lazic, conventional intra lazic, custom view intra lazic. These are all variations on the basic lazic approach basic lazing, and there are of course

complications with some of these. We mentioned some before. I've I've known people to undergo lasic and complain of some problems with night vision where they see halos. There's a lot of that where everyone looks like master Chief No. Um. Basically, when you look at a light source, it looks like it has shimmering circle around it. Yeah. Yeah, especially things for like if you're driving at night and you'll know no halos around headlights things like that, or you're sensitive

to bright light. Yeah, yeah, you're light sensitivity. Especially for the first few days, it's probably gonna be a little, uh, a little rough. But for some people it just it stays that way. So like my wife, she wears sunglasses a lot more frequently than she used to. And uh for for some people too, I've heard that in some cases, uh, it is possible for your eyes basically to slowly regress to where they were before. Um. I don't know exactly why that is, you know, I have read reports that

that it happens. Um. But and you know, some people who have and you know, enjoyed the benefits of the surgery for years, and then there are others who gradually returned to uh, to the way they were before. I'm sure that it probably since since part of the corney has been removed, I would imagine that it's probably not as uh drastic a change so it was. But I've

I've read that that that can happen. I would imagine if you have some sort of condition that continues to change the shape of your eyeball, that would be that would be a big problem because the focal point would constantly be changing then or gradually be changing. Well, guys, that's it. That's another classic episode of tech Stuff in the books. I really love looking back on these After recording more than a thousand episodes of this show, it's sometimes a journey of discovery for me to go back

and look at these old episodes. And also it's just fun to think back on working with Chris Poulette. He was a great co host and editor. So Chris, if you're out there listening to this, we miss you, buddy. If you, guys, suggestions for future episodes of tech Stuff, whether it's a technology, a company, a person in tech, maybe there's someone you would like me to interview on the show, let me know. Send me an email. The addresses tech Stuff at how stuff works dot com or

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