LASIK is a two step laser vision correction procedure to improve vision. The second step is reshaping the cornea in the front of the eye with an excimer laser to include the power needed from glasses or contact lenses onto the eye.
Watch this episode of A State of Sight with Isaac Porter, MD to learn more about the second part of LASIK eye surgery.
If you want to review the first step in LASIK, flap creation, look back to episode #130 of A State of Sight: https://youtu.be/_LSm0E297EE
Welcome to A State of Sight, I’m Isaac Porter and this is your update in ophthalmology and eye care from Raleigh. Today, I would like to cover the second step of LASIK, which is changing the shape of the cornea.
If you look back at the last episode of A State of Sight we covered the first step of LASIK, creating the flap. Once we move on to the second step, the patient is moved to a different laser. Currently, we use the Visx Star S4 IR laser.
These lasers that change the shape of the cornea are called excimer lasers. From the patient’s experience, they first notice the safety device that is used to help keep their eyelids open. Then we lift the flap in the front of their cornea that has been created by many, many bubbles from our Zeiss Visumax femtosecond laser.
This flap includes the outer layers at the front of the cornea and it is lifted with a hinge remaining at the top of the cornea. Then we use the excimer laser to change the shape of the cornea.
This laser contains a red-orange target light that the patient looks at to help keep their eye steady. As an additional safety feature, the laser is tracking their eye before every single pulse to make sure it is in the right position. If the eye is not aligned properly, then the laser stops until it is safe to proceed again..
Most of the time, the laser treatment lasts less than 30 seconds. Then we finish the procedure by smoothing the flap back down, making sure there is nothing underneath the flap, and that it is in a great position. With this part of the laser eye surgery, our patients may feel a couple of drops on their eye and we ask them to keep looking straight ahead. First we treat the right eye, then we go on to treat the left eye.
On the technical side, the way that the laser actually works is that with every single pulse from the laser, a very tiny amount of tissue is removed from the cornea. Using precise calculations from engineers that are much smarter than I am, they have been able to determine exactly how the laser needs to fire on the cornea in order to include the power needed from glasses or contact lenses onto the eye.
For people who are nearsighted, the cornea is flattened just a little bit to make it less steep. In these treatments (myopic LASIK), most of the laser pulses are towards the center of the cornea. In the outer parts of the cornea, there is less and less treatment with less tissue removed.
The excimer laser is a cool laser, so it doesn’t generate heat or any sensation that the patients can feel, but they can hear the sound that the laser makes when it is running. If you have any other questions about LASIK eye surgery, either this step or the one before, please post and we will be happy to answer them. I hope to see you again soon, next time on A State of Sight.