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LASIK and PRK basics, laser vision correction explanation - A State of Sight #4

Laser vision correction can reduce your dependence on glasses and contact lenses. Isaac Porter, MD, explains how LASIK and PRK work to correct vision by reshaping the cornea. Nearsightedness (myopia), farsightedness (hyperopia), and astigmatism can be corrected with the excimer laser in LASIK.



Welcome to A State of Sight, I’m your host Isaac Porter from Lowry Porter Ophthalmology and this is your update in ophthalmology and eye care. Over the past week, I’ve been a little bit sick with a cold and I lost my voice, but I’m feeling better now and my voice is getting stronger and now I’m ready to bring you our latest episode covering the basics of LASIK eye surgery.


There are two main types of laser vision correction that are performed today, LASIK, which you’ve probably heard about more often, and PRK. A couple variations of PRK are epi-LASIK and LASEK, but these are basically types of PRK.


All types of laser vision correction aim to include the power of a person’s contact lens or their glasses onto the eye to decrease their need for wearing contacts or glasses and to improve their uncorrected vision.


The way this works, the shape of the eye is changed with the laser that actually removes some of the tissue from the eye in order to change the curvature. In people that are nearsighted this curvature is flattened and in people that are farsighted it can be steepened.


Laser vision correction can also correct for astigmatism and in these cases the curvature is brought to a more round shape to allow the light to pass through better. The way that the laser works in someone, for example, who is moderately nearsighted is the laser would have to remove about 50 microns of tissue from the cornea.


50 microns is less than half the thickness of a sheet of paper, so you can imagine how accurate this laser is to be removing such a thin amount of tissue from the cornea.


The way it works for nearsightedness is it will remove 50 microns from the center of the cornea, a little bit out from that area it will remove 49, a little bit further out, 48, 47, all the way until it gets to the edge of the treatment where only 3, 2 and 1 microns are removed.


That creates a new shape to the cornea that used to be steeper, but by removing the tissue, it’s flattened a little bit to include the power from the glasses onto the cornea.


In a custom laser vision correction treatment, or a wavefront guided treatment, those numbers will vary some and won’t be exactly 50 smooth on down to 1 at the edge, there will be some variations in the area that are unique to that patient’s eye.


This is somewhat like a fingerprint of the eye, therefore the laser can correct even the smallest errors in their vision. I have a lot more to show with you about LASIK and laser vision correction, but that’s enough for this week.



If you are checking out our past episodes, you may be able to click through and already see some of the other episodes about LASIK, but for now that’s all we have for this week.


Please leave comments on below and let us know if you’ve had LASIK before, or if you have any questions about LASIK. Until next time, good health and good sight.