How does laser eye surgery work? – Dan Reinstein


In 1948, Spanish ophthalmologist
Jose Ignacio Barraquer Moner was fed up with glasses. He wanted a solution for blurry
vision that fixed the eye itself, without relying on external aids. But the surgery he eventually devised
was not for the faint of heart. Barraquer began by slicing off the front
of a patient’s cornea and dunking it in liquid nitrogen. Using a miniature lathe, he ground the
frozen cornea into the precise shape necessary to focus
the patient’s vision. Then he thawed the disc, and sewed
it back on. Barraquer called this procedure
keratomileusis, from the Greek words for “carving”
and “cornea.” And though it might sound grisly,
his technique produced reliable results. So how did Barraquer’s surgery work? Keratomileusis corrects what are called
refractive errors: imperfections in the way the eye focuses
incoming light. Ideally, the cornea and lens work
together to focus light on the surface of the retina, but several kinds of refractive errors
can impair this delicate system. In people with myopia,
or short-sightedness, a steep cornea focuses light just short
of the retina. Those with hyperopia, or far-sightedness,
have the opposite problem: light is focused too far
beyond the retina. And in people with astigmatism,
the cornea has two different curvatures which focus light at two distances and
produce blurry vision. Even those with perfect vision will
eventually suffer from presbyopia, or “aging eyes.” As the proteins in the lens age, they
slowly increase its size. By an adult’s mid-40’s, the lens is too
large to easily change shape and shift focus. Glasses and contact lenses bend light
to compensate for these refractive errors. But, as Barraquer’s procedure shows, we can also alter the shape
of the cornea itself; moving the focal point backwards,
forwards, or pulling a divided image together. And thankfully, modern eye surgeons can
sculpt the cornea with far less invasive tools. In corrective laser eye surgery, surgeons
rely on excimer lasers. These tools are accurate enough to etch
words into a human hair. To safely accomplish these
ultra-fine incisions, they use a technique called photoablation. This allows the laser to essentially
evaporate organic tissue without overheating
surrounding eye tissue. So how does laser eye surgery
actually work? The first step is to separate a thin layer
from the front of the cornea. This can be done with either a flat,
wide blade, or a femto-second laser that produces millions of tiny plasma
bubbles to create a plane beneath
the corneal surface. Surgeons then lift the flap to expose the
inside of the cornea. Guided by the refractive error and the
shape of the cornea, the excimer laser robotically sculpts the
exposed corneal bed into the correct shape. This process usually takes less than 30
seconds for each eye. Finally, the flap is closed, and its edges reseal themselves
in just a few hours. Because the lasering is done on
the eyeball itself, it’s described as “in situ,” or “on site.” Its complete name is “laser in-situ
keratomileusis” – but you probably know it as LASIK. Essentially, this technique carves a
patient’s contact lens prescription onto their cornea. Like any surgical procedure, LASIK comes with certain risks. Some patients experience slightly blurred
vision that can’t be corrected by glasses. But the technique is currently about
as likely to damage your eyes as wearing daily disposable contact
lenses for one year. Today, a technique called SMILE enables
surgeons to sculpt the cornea through even smaller incisions – further reducing recovery time. And lasers aren’t just correcting the
three types of refractive errors – this technology can also
restore aging eyes. In a technique called Laser
Blended Vision, surgeons adjust one eye to be slightly
better at distance vision and the other to be better
at close range vision. The difference between the two eyes is
small enough that most patients can merge their vision, allowing both eyes to work
together at all distances. Advances in laser technology continue
to make vision correction surgery more effective and accessible. One day soon, Barraquer’s vision of a
world without glasses may finally come true.

100 thoughts on “How does laser eye surgery work? – Dan Reinstein

  1. But what happens if they make a mistake. I hear of people who are still in pain because of that. Not to mention pain killers have side effects.

  2. WARNING 'RE EYE OPS! Google the Optical Express Ruined my Life website and Facebook page for information. OERML is not just about OE, but the whole UK refractive eye surgery industry which is actually UNREGULATED! Laser eye ops cause permanent corneal nerve damage which can result in horrific eye pain, and lens replacement ops involve bodge job multifocal lenses that cause severe vision distortions that may make it impossible to drive at night or even at all! It's Russian Roulette! Ask Dan Reinstein about Anneka Rice, who publicly stated that following her laser eye ops performed by him that her vision was worse than before, and she didn't know when or even if it would ever be right!

  3. Dear TedEd, You missed out on PRK, which is a knife-less variant of laser-ablation based sculpting, arguably superior to LASIK. It has the advantage of not having a "flap" in your eye to worry about for the rest of your life, in exchange for a few days of discomfort.

  4. Why do most optometrists wear glasses? Why do most optometrists performing this surgery wear glasses? Yeah, that’s why.

    I would love to have perfect eye sight, but I’d rather live through the lifetime inconvenience of wearing contacts or glasses rather than risk a lifetime of blindness.

    I’ve heard of people who had this surgery performed on them and had good temporary results, but after a while their vision got worst than what they originally had before the surgery and had other complications. Plus, I think you’re not allowed to be an AirForce pilot or even a general airline pilot if you’ve had this procedure performed on you. So, if these agencies forbid you from being a pilot if you’ve had this surgery performed on you, then that should suggest to you the confidence and reliability of this surgery — despite all those reviews or claims of 95% positive results.

  5. "Safely" lol 30% of people who get this surgery have issues right after or even years after.
    The man who pushed it to be FDA approved now wants it to be reversed.

  6. TED ED I want to say that your videos are really beneficial to me as a student☺️…and I wanted to request you to kindly make videos on topic like: Eye dieseas (Cataract, Pressbiopia etc) and on Hydraulic system, Dynamic lift etc… Please they will really help me out(only if you are convient with these topics).🤗

  7. Can you imagine?
    "Uhh, I'd rather shoot my eyes out with a laser than wear these glasses any longer!…… wait a minute"

  8. I think that I could never have my eyes operated by laser… my fear of it is probably too big, just the idea of such an operation is terrible for me. Thank god i see well, and if I get older I will only have glasses.

  9. I was interested in getting laser eye surgery myself until I came to 3:20 and nope, nope, nope, I just love my myopia!

  10. The history is correct and the video is awesome, but there is a small error. The ophthalmologist pictured in this video is José Barraquer Barraquer (José Ignacio Barraquer Moner's father). Easy mistake to make, as father and son both were ophthalmologists, shared a common name, and looked a lot alike.

  11. Fascinating. I think though that the world without glasses might only be a thing though for people in their late 20s or older. If kids or teens get the surgery their eyes still change again and then since they skimmed their cornea once they have less to spare for a second surgery.

  12. Hi everyone, sorry to bother you but this is something very important for me, I recently learned that I won't be able to continue my University studies in medical school here in my country since my parents are struggling financially and can't pay for it anymore, any help would be greatly appreciated, please enter this link( https://gogetfunding.com/help-me-chase-my-dreams/ ) or if you want to send me and encouraging message, do it here [email protected] 😊 have a good day/night. Thanks.

  13. A better way to fix blurry/blind vision is to trade eyes with your siblings, so that you can have Eternal Mangekyou Sharingans.

  14. A better way to fix blurry/blind vision is to trade eyes with your siblings, so that you can have Eternal Mangekyou Sharingans.

  15. A better way to fix blurry/blind vision is to trade eyes with your siblings, so that you can have Eternal Mangekyou Sharingans.

  16. A better way to fix blurry/blind vision is to trade eyes with your siblings, so that you can have Eternal Mangekyou Sharingans.

  17. A better way to fix blurry/blind vision is to trade eyes with your siblings, so that you can have Eternal Mangekyou Sharingans.

  18. As soon as I'm done with school and not broke for 1 second I'm gonna save up and get Lasik. I'm sick of wearing glasses and contacts.

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