Everything You Have Ever Wanted to Know About Vision Correction Surgeries

Glasses and contacts might be a thing of the past with all the new vision correction surgeries.

Bad vision used to be a curse that one had to live with, but no longer. The last ten years have seen enormous strides in vision correction surgeries.

RELATED: HOW DO EYEGLASS LENSES WORK TO CORRECT YOUR VISION?

Vision correction surgery, also called refractive surgery, refers to any surgical procedure that is used to fix vision problems. Some types of surgery reshape the cornea. This is the clear part at the front of your eye that lets light through to your eye, where it is focused at the back of the eye, or retina. Other types of surgery either augment or replace your eye's natural lens.

LASIK

Short for laser in-situ keratomileusis, it involves the doctor cutting a flap in the outer layer of your cornea, allowing him to access the tissues underneath. The doctor uses a laser to reshape that tissue so that it focuses light properly, then the flap is closed.

LASIK procedure
LASIK procedure Source: U.S. Air Force

The doctor may also use a type of computer imaging called wavefront technology, that creates a detailed image of your cornea that can be used as a guide. LASIK works for people who are nearsighted, farsighted or have astigmatism.

PRK

PRK stands for photorefractive keratectomy, and it is used to correct mild to moderate nearsightedness, farsightedness, or astigmatism. With PRK, the doctor uses a laser to reshape the surface of your cornea and not its underlying tissues. The doctor may also use computer imaging of your cornea.

PRK procedure
PRK procedure Source: Chad A. Bascom/Wikimedia Commons

SMILE

SMILE is an acronym for SMall Incision Lenticule Extraction. In it, a very small flap is made in the cornea, 4 mm as compared to 20 mm required in LASIK. SMILE surgery is performed using a VisuMax femtosecond laser, which is proprietary technology of Carl Zeiss Meditec.

The laser creates a small, lens-shaped bit of tissue, called a lenticule, within the cornea. Then, through an incision, the surgeon extracts the lenticule and the shape of the cornea is permanently altered. The corneal incision heals within a few days without stitches.

RLE, CLE and RLR

RLE stands for refractive lens exchange, CLE stands for clear lens extraction and RLR stands for refractive lens replacement. All these acronyms refer to the same procedure, which is the same as cataract surgery.

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Intraocular lens
Intraocular lens Source: Frank C. Müller/Wikimedia Commons

The doctor makes a small incision at the edge of your eye, removes your natural lens, and replaces it with a plastic lens implant. This procedure can correct extreme farsightedness or nearsightedness, and it works well in people whose corneas are not ideal for cornea-based surgeries. These include people with thin corneas, dry eyes, or other cornea problems.

RLE, CLE and RLR can be combined with LRI to correct astigmatism.

PRELEX

PRELEX is short for presbyopic lens exchange. Presbyopia is what happens to those of us over 40, where a loss of flexibility in the lens of your eye causes you to have problems seeing up close. Think of someone in a restaurant holding their menu at arms length.

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In PRELEX, the doctor removes the clear lens and replaces it with a multifocal lens, allowing you to see near, far and in between.

Corneal Inlays and Onlays

As their names imply, corneal inlays and corneal onlays are inserted within the cornea to improve reading vision for those experiencing presbyopia. Onlays are placed near the surface of the cornea, under the thin outer layer called the epithelium.

Inlays are placed in the thicker middle layer of the cornea, which is called the stroma. Because they are implanted deeper, inlays may be more stable, and deliver more predictable and long-lasting results than onlays. Inlays are a good option for people whose corneas are too thin for LASIK or PRK.

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Intacs/ICR

Intacs stands for intracorneal ring segments, or ICR. In this procedure, the doctor makes a small incision in your cornea, and places two crescent-shaped plastic rings at the outer edges. The rings flatten the cornea and change the way light hits the back of your eye.

While this procedure isn't frequently used to treat nearsightedness any longer, it is used to treat keratoconus, which is an irregularly-shaped cornea that thins to a dangerous level, and can lead to vision loss. 

LRI

LRI is short for limbal relaxing incisions, and it is used to correct astigmatism. When you have astigmatism, instead of your cornea being round like a basketball, it is shaped more like a football. The doctor makes one or two incisions in the steepest part of your cornea, and the cornea relaxes and becomes more rounded. LRI can be done alone, or in combination with other eye surgeries like RLE.

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Phakic IOLs

IOL stands for intraocular lens, and phakic IOLs are clear implantable lenses that are surgically placed either between the cornea and the iris (the colored portion of your eye) or just behind the iris. Unlike a contact lens, you can't feel a phakic intraocular lens in your eye.

In the U.S. two types of IOLs are approved by the Food and Drug Administration (FDA) — the Visian ICL (Implantable Collamer Lens) made by Staar Surgical is implanted in the posterior chamber behind the iris and in front of your eye's natural lens. The lens is made of a soft, biocompatible collagen copolymer that can be folded to aid in implantation.

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The Verisyse IOL is placed in the anterior chamber in front of the iris. It is made of polymethylmethacrylate, or PMMA and is rigid.

Advanced Surface Ablation (ASA)

This procedure is performed on the surface of the cornea, and is used on patients who have thin corneas or loose corneal cells. These conditions make them poor candidates for LASIK.

In ASA, an excimer laser reshapes the front surface of the cornea to correct vision. Following the procedure, a soft contact lens is placed on the eye to aid in the healing process.

Problems

Like any surgery, there can be problems with vision correction surgeries. A very small number of people can get an infection after PRK or LASIK. Some people experience corneal haze following PRK, and this can affect your vision.

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Following PRK or LASIK, you can experience what's known as the halo effect. In dark places, as your pupil opens, you can see a second image or halo. This can make driving at night particularly difficult. People with higher degrees of nearsightedness are more prone to experience the halo effect.

With any of these vision correction surgeries, your doctor will make his or her best guess, but you won't know how well your surgery worked until your eyes have healed. You may still need to wear glasses or contact lenses.

With either PRK or LASIK, there can be what's called regression, where your eyes return to their original condition several months after surgery. You will then need a second surgery in order to set things right.

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A rare complication is worse vision than before the surgery. Another rare complication is damage to the LASIK flap caused by a direct blow to the eye.

Surgery to Change Your Eye Color

For years, doctors have used iris implant surgery to treat traumatic eye injuries and medical conditions such as aniridia, where the eye's iris is missing, or coloboma, where part of the iris is missing.

Lately, this procedure has become popular for changing a person's eye color. The procedure hasn’t been evaluated by regulators in the U.S., and it hasn't undergone clinical trials. People in the U.S. wanting the procedure must travel overseas.

In 2014, the American Academy of Ophthalmology came out against cosmetic iris implant surgery. They warned that the procedure could lead to severe eye complications, including vision loss and blindness.

Another procedure has been developed, where a laser is used to remove pigment from the layer of tissue in the iris called the stroma. Removing pigment can turn a brown eye a lighter color, such as blue. This procedure is currently undergoing clinical trials.

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