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Speaker 1: Welcome to brain stuff from How Stuff Works. Hi, I'm

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Speaker 1: Christian Sager, and welcome to brain stuff. When was the

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Speaker 1: last time you got to use an eyelid speculum? You

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Speaker 1: know those small metal prongs that push your eyelids open

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Speaker 1: clockwork orange style. WELLEMI drugs. I hope the answer is never.

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Speaker 1: But if you have been subject to one of these

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Speaker 1: uncomfortable devices, it's probably because you've had corrective surgery to

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Speaker 1: your vision. See. Our corneas are like windows that allow

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Speaker 1: light to pass through our retinas where it's converted into

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Speaker 1: electrical signals to our brain. If you have eyesight problems,

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Speaker 1: it's usually because your eye can't focus an image onto

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Speaker 1: your retina. For centuries, we've relied on external lenses like

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Speaker 1: glasses or contacts for correction, But with modern technology, surgeons

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Speaker 1: can actually alter the shape of the eye itself, using

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Speaker 1: lasers to change its focal point. The most popular technique

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Speaker 1: is called LASIC, which stands for laser assisted in Puto

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Speaker 1: karatma lusis. It's very effective at treating several visual problems,

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Speaker 1: especially near sightedness. Before any reputable eye doctor performs LASIC,

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Speaker 1: they're going to give you a thorough preoperative eye exam.

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Speaker 1: They'll measure your current prescription and manually check the surface

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Speaker 1: of your cornea with a dye called flu or a cane.

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Speaker 1: Other tests map your corneas topography and measure the exact

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Speaker 1: diameter of your pupil. To qualify for LASIC, you'll need

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Speaker 1: to meet a certain range of vision, corneal thickness, and

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Speaker 1: pupil size. It's also risky if you're pregnant, have severe

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Speaker 1: heart problems, certain diseases, or take some types of drugs.

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Speaker 1: Once you've passed preopp assessment, you come back for the

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Speaker 1: actual LASIC process, conducted by both the surgeon and a

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Speaker 1: technician operating the laser machine. They'll put a topical anesthetic

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Speaker 1: in your eyes to numb any discomfort, and that's good

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Speaker 1: because the next step is to eye open your eyes

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Speaker 1: with special tape and that good old eyelid speculum. Then

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Speaker 1: they'll calibrate the laser and mark your cornea for alignment

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Speaker 1: using a suction ring with an extremely precise surgical blade

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Speaker 1: called a micro kera tom, the surgeon cuts a flap

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Speaker 1: in your cornia and folds it back. You'll be asked

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Speaker 1: to focus on a red light which isn't the laser

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Speaker 1: but helps center your eye. Now it's laser time. A

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Speaker 1: laser mixing reactive gases like chlorine and fluorine with inert

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Speaker 1: gases like argon, crypton, and xenon, produces a tightly focused

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Speaker 1: beam of ultraviolet light that vaporizes a microscopic portion of

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Speaker 1: the cornea. This is a cool laser that doesn't heat

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Speaker 1: the surrounding air or surface. Instead, it breaks down the

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Speaker 1: molecular bonds of organic materials. The beam itself is microscopic,

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Speaker 1: less than a nanometer wide. The surgeon reshapes the cornea

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Speaker 1: by controlling the size, position, and number of laser pulses applied. Surprisingly,

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Speaker 1: this only takes a few seconds. When it's finished, your

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Speaker 1: corneal flap is replaced with a small antibiotic added. The

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Speaker 1: cornea heels and rebonds, immediately naturally sealing itself. Again. Taking

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Speaker 1: into account the time for both eyes, the entire procedure

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Speaker 1: is usually done in only fifteen to thirty minutes. After

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Speaker 1: the operation, they'll give you these cool eye shields that

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Speaker 1: prevents you from touching your eyes but let you see

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Speaker 1: enough to get around. You'll wear them for the rest

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Speaker 1: of the day and sleep in a mask that night.

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Speaker 1: Of course, someone has to drive you home, and once

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Speaker 1: you get there, you'll need to apply rewedding drops, antibiotic drops,

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Speaker 1: and possibly a moisturizing gel inside your bottom eyelid. The

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Speaker 1: ophthalmologist will follow up the next day on a recurring

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Speaker 1: basis for about a year. Now you're probably asking, but Christian,

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Speaker 1: couldn't there be side effects when a doctor shoots a

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Speaker 1: laser into my eye? Well, yeah, of course there could.

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Speaker 1: Most commonly, eyes can be under corrected, overcorrected, or get

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Speaker 1: a small wrinkle when the corneal flap is replaced paste

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Speaker 1: that causes a blur. For the most part, these are

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Speaker 1: easily fixed with a second procedure. Sometimes a surgeon won't

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Speaker 1: even recommend further refining, since many recipients of lasik never

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Speaker 1: achieve normal vision, but do reduce their corrective prescriptions significantly.

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Speaker 1: Other rarer side effects can include halos around lights, light sensitivity,

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Speaker 1: and double vision. I'd be lying if I said there

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Speaker 1: wasn't a chance of partial or complete blindness, but it

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Speaker 1: is minuscule compared to the success rate. This is especially

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Speaker 1: true if you're seeing a reputable doctor. Keep in mind,

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Speaker 1: there are so many unscrupulous practitioners out there that the

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Speaker 1: f d A actually had to issue a stern warning

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Speaker 1: about dodgy sales pitches underplaying the risks of lasik. But

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Speaker 1: twenty five years after it was invented by Golem payment,

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Speaker 1: lasic is safer than ever before. There's other types of

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Speaker 1: eye surgery to including radial car atautomy, automated lamellar keratoplast see,

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Speaker 1: and photo refractive care atatomy. All of them, however, involved

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Speaker 1: slicing up your cornea to some degree. Check out the

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Speaker 1: brainstuff channel on YouTube, and for more on this and

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Speaker 1: thousands of other topics, visit how stuff works dot com