There are three common refractive eye surgeries designed to correct refractive vision errors. The best known refractive surgery is LASIK. The name is an acronym and stands for “Laser-Assisted In Situ Keratomileusis” which is a combination of English, Latin, and Greek that literally means using a laser to reshape corneas while the corneas are in their natural place.
The two other vision correction surgeries share similar compound names, but they all correct vision by reshaping the cornea.
Why Reshape the Cornea?
The cornea is the eye’s outermost lens. It is a tough, transparent membrane that shields the eye and provides about 80% of the eye’s refractive (focusing) power. The shape of the cornea determines how it bends (refracts) rays of light.
A cornea curved too steeply causes nearsightedness (myopia), and a flat cornea causes farsightedness (hyperopia). An astigmatism is caused by corneas that have mismatched curves.
LASIK and other laser-assisted vision correction surgeries use lasers that emit high-energy pulses of cool ultraviolet beams of light that remove microscopic amounts of the cornea to reshape it. The lasers remove tissue with no heating or damage to nearby corneal tissue. The lasers are controlled by computer and programmed with the precise measurements needed to reshape your corneas to correct your specific refractive error.
High-energy lasers have transformed eye surgery, increasing its safety, accuracy, and predictability. The lasers have automated eye-tracking that monitors eye movements and keeps the laser beam on target during the surgery. The procedure itself takes between 20 to 60 seconds depending on the refractive error. But the process takes longer.
You must stop wearing contact lenses for several weeks before refractive correction surgery because contact lenses distort the natural shape of your cornea which can lead to inaccurate pre-surgical measurements.
Detailed measurements of your corneas are made, and your surgeon will use them to program the laser with the desired measurements needed to reshape your cornea and correct your vision.
- To correct nearsightedness (myopia) the cornea is flattened by removing more corneal tissue from the center than from the edges.
- To correct farsightedness (hyperopia) corneal tissue from the periphery is removed.
- To correct astigmatism the cornea is remolded to be uniformly shaped. This is done by removing move tissue in one direction than another.
Most people can return to work the next day. It is common for the eyes to continue to heal for at least 3 months and during the healing process your vision will also continue to improve. If your corrective prescription was severe, healing could continue for up to 6 months. Follow all your surgeon’s post-operative instructions to ensure optimum healing.
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