how does laser eye surgery work

What is Laser Eye Surgery?

According to Lasik.com "Laser eye surgery is an umbrella term for several eye surgeries used to correct refractive errors (i.e., how your eye focuses light). The most common types of laser eye surgery include LASIK, PRK, LASEK and EpiLASIK.
Each of the four laser eye surgery procedures below uses the same special laser, called an “excimer” laser, to reshape the cornea. This is what corrects vision. But laser eye surgery can vary in the specifics of the procedure, the recovery time, which surgical instruments are used and your patient candidacy."

The National library of Medicine USA informs that " For many people, laser eye surgery can correct their vision so they no longer need glasses or contact lenses. Laser eye surgery reshapes the cornea, the clear front part of the eye. This changes its focusing power.

There are different types of laser eye surgery. LASIK - laser-assisted in situ keratomileusis - is one of the most common. Many patients who have LASIK end up with 20/20 vision. But, like all medical procedures, it has both risks and benefits. Only your eye doctor can tell if you are a good candidate for laser eye surgery."

The FDA has a broken down the steps on how does laser eye surgery works:

If you decide to go ahead with LASIK surgery, you will need an initial or baseline evaluation by your eye doctor to determine if you are a good candidate. This is what you need to know to prepare for the exam and what you should expect:

If you wear contact lenses, it is a good idea to stop wearing them before your baseline evaluation and switch to wearing your glasses full-time. Contact lenses change the shape of your cornea for up to several weeks after you have stopped using them depending on the type of contact lenses you wear. Not leaving your contact lenses out long enough for your cornea to assume its natural shape before surgery can have negative consequences. These consequences include inaccurate measurements and a poor surgical plan, resulting in poor vision after surgery. These measurements, which determine how much corneal tissue to remove, may need to be repeated at least a week after your initial evaluation and before surgery to make sure they have not changed, especially if you wear RGP or hard lenses.  If you wear:

• soft contact lenses, you should stop wearing them for 2 weeks before your initial evaluation.
• toric soft lenses or rigid gas permeable (RGP) lenses, you should stop wearing them for at least 3 weeks before your initial evaluation.
• hard lenses, you should stop wearing them for at least 4 weeks before your initial evaluation.

The surgery should take less than 30 minutes. You will lie on your back in a reclining chair in an exam room containing the laser system. The laser system includes a large machine with a microscope attached to it and a computer screen. (See the animation of the LASIK procedure.)

A numbing drop will be placed in your eye, the area around your eye will be cleaned, and an instrument called a lid speculum will be used to hold your eyelids open.

Your doctor may use a mechanical microkeratome (a blade device) to cut a flap in the cornea.

If a mechanical microkeratome is used, a ring will be placed on your eye and very high pressures will be applied to create suction to the cornea. Your vision will dim while the suction ring is on and you may feel the pressure and experience some discomfort during this part of the procedure. The microkeratome, a cutting instrument, is attached to the suction ring. Your doctor will use the blade of the microkeratome to cut a flap in your cornea. Microkeratome blades are meant to be used only once and then thrown out. The microkeratome and the suction ring are then removed.

Your doctor may use a laser keratome (a laser device), instead of a mechanical microkeratome, to cut a flap on the cornea.

If a laser keratome is used, the cornea is flattened with a clear plastic plate. Your vision will dim and you may feel the pressure and experience some discomfort during this part of the procedure. Laser energy is focused inside the cornea tissue, creating thousands of small bubbles of gas and water that expand and connect to separate the tissue underneath the cornea surface, creating a flap. The plate is then removed.

You will be able to see, but you will experience fluctuating degrees of blurred vision during the rest of the procedure. The doctor will then lift the flap and fold it back on its hinge, and dry the exposed tissue.

The laser will be positioned over your eye and you will be asked to stare at a light. This is not the laser used to remove tissue from the cornea. This light is to help you keep your eye fixed on one spot once the laser comes on. NOTE: If you cannot stare at a fixed object for at least 60 seconds, you may not be a good candidate for this surgery.