LASIK stands for Laser assisted In-situ Keratomileusis. It is a two-step procedure for correcting refractive error, such as nearsightedness, farsightedness or astigmatism. It is currently the most common refractive surgery procedure performed in the U.S.
The entire procedure focuses on the clear surface of the eye called the cornea. This is the same part of the eye where contact lenses are placed for vision correction. When contact lenses sit on the cornea, they change the way that light is bent as it enters the eye. For farsighted people the contact lens bends the light more. For nearsighted people it bends the light less. However, with LASIK, a very sophisticated and precise laser is used to permanently reshape your eye, making it flatter or steeper to correct the error that exists on the surface of the eye. This creates a permanent solution for refractive error that can’t be achieved with contact lenses.
The first step in the two-step process is the creation of a thin flap on the surface of the eye. A special instrument, called a microkeratome, is used to create a thin flap on the surface of your eye. Just like a cheese wire creates a flap when pulled through a block of cheese, the mircokeratome creates a flap in the cornea. This is a very sophisticated process that takes about 15 seconds and is completely painless. This step allows the surgeon access to the middle portion of the cornea where the resurfacing will take place. In some instances, you or your surgeon may elect to use a laser to create the flap. The laser used to create this flap at the Texas Vision & Laser Center is a femtosecond laser called Intralase, and is a completely different laser than the one used to reshape the eye. To find out more about Intralase click on the link.
Once the flap is created it is pulled back and the second step is performed. The second step involves the reshaping of the cornea by using a very precise excimer laser. The Texas Vision & Laser Center uses the VISX Star S4 excimer laser capable of tracking the very fine movements of the eye at a rate of 10,000 times per second. The usual treatment time will vary depending on the amount of correction needed. But, typically it ranges from 10 to 50 seconds per eye.
Once the laser completes the reshaping of the cornea, the surgeon repositions the flap, and the same two-step procedure is performed on the other eye if both eyes require correction. Once this is completed the flap immediately begins to seal back into place. After about 24 hours the flap is completely sealed. However, it can take two to four weeks for the flap to completely heal. During this time patients may experience mild fluctuations in vision, and are counseled not to rub their eyes or to go swimming.
After the Procedure
To help with the healing process, prescription eye drops are used for approximately one week after surgery. For the first week after surgery, patients are asked to wear a shield over the eyes while sleeping. For the first month after surgery, patients are asked to use artificial tears to help minimize any drying of the eye surface.
For the first few hours after LASIK, patients experience a mild irritation that may feel like something in the eye. However, this irritation rapidly dissipates over the following five to six hours. Keeping the eyes closed at all times, and lubricated with artificial tears, will minimize the intensity and duration of these symptoms.
Immediately after surgery, patients will experience hazy and blurred vision that will persist for the rest of the day. This will slowly improve as the day progresses. However, the vision will not be significantly better until the following day. The next day, most patients have good enough vision to drive themselves to their follow-up appointment without the use of glasses.
There are many different variables to the LASIK procedure depending on the surgeon and facility you choose. These variables may include the use of different microkeratomes to create the flap or a femtosecond laser like Intralase to make the flap. A second variable that may exist is the brand of excimer laser that is used. There are several different excimer lasers that exist- all are not equal, with some having broader treatment ranges and more sophisticated features.
A third variable to LASIK is usually given as an option to patients. It is an option to select between “conventional” or “wavefront” LASIK. These two options refer to the software used by the laser to reshape your eye. When your eye is measured in the pre-operative exam, the amount of error is recorded by the doctor and used by the laser to calculate the treatment needed to correct the error. Those calculations are performed by either a conventional software program or a wavefront software program to produce a treatment plan. Conventional software programs use simpler calculations, require less information and are usually sufficient for people with small amounts of refractive error. Wavefront software programs use complex calculations that take into account much more information about the eye. People with complex refractive error, or who have larger amounts of refractive error, usually do better with wavefront technology. The name of the wavefront software for the VISX laser is CustomVue, and the wavefront procedure with this laser is referred to as Custom LASIK. You and your doctor will have to determine which procedure, conventional or wavefront, is best for you.