Laser Vision Correction Conditions & Procedures

Overview of Laser Vision Correction

Overview of Laser Vision Correction

Laser vision correction utilizes a sophisticated laser to reshape the cornea and decrease the need for glasses or contact lenses used for nearsightedness, farsightedness and astigmatism. These procedures include, LASIK, LASEK, epi-LASIK, PRK and PTK. The effect of this surgery is permanent, however in a small percentage of patients there may be a need for an enhancement after the initial surgery. Most, if not all patients will require reading glasses when they reach their 40s.

As with any surgery, there are certain risks associated with laser vision correction procedures. Be sure to discuss these possible risks with your ophthalmologist.

About LASIK Surgery

About LASIK Surgery

Until recently, if you were one of the millions of people with a refractive error, eyeglasses and contact lenses were the only options for correcting vision. But with the development of refractive surgery, some people with myopia (nearsightedness), hyperopia (farsightedness), or astigmatism (a cornea with unequal curves), can have their vision improved surgically.

Laser-assisted in situ keratomileusis (LASIK) is a refractive procedure that uses a laser to permanently reshape the cornea. The reshaped cornea helps focus light directly onto the retina to produce clearer vision.

LASIK is usually performed as an outpatient procedure using topical anesthesia with eyedrops. The procedure itself generally takes about 15 minutes. The surgeon creates a flap in the cornea with a special laser called a femtosecond laser. Tiny, quick pulses of laser light are applied to your cornea, creating microscopic bubbles at a specific depth and position within your cornea. Your ophthalmologist creates a flap in the cornea by gently separating the tissue where the bubbles have formed, and the flap is then folded back. The cool beam of a second laser, called an excimer laser, is used to remove a thin layer of corneal tissue. The flap is folded back to its normal position and sealed without sutures. The removal of corneal tissue permanently reshapes the cornea.

A clear shield protects the flap for the first day and night. Vision is usually slightly cloudy immediately after the procedure, but it clears rapidly, often within just a few hours. Your vision should be clear by the next day. Healing after surgery is often less painful than with other methods of refractive surgery, because the laser removes tissue from the inside of the cornea and not the surface. You will need to use antibiotic and steroid eyedrops several times a day for the first week, along with rewetting drops. After the first week, you will need to use only the rewetting eyedrops.

Some people experience poor night vision after LASIK. The surgery also may result in undercorrection or overcorrection, which can often be improved with a second surgery. More rare and serious complications include a dislocated flap, epithelial ingrowth, and inflammation or infection underneath the flap. Most complications can be managed without any loss of vision. Permanent vision loss is very rare.

The ideal candidate for LASIK has a stable refractive error, adequate corneal thickness and normal corneal shape, is free of eye disease, is at least 18 years old, and is willing to accept the potential risks, complications, and side effects of LASIK.

Enhanced LASIK with Wavefront technology

Wavefront-guided LASIK is an enhanced version of LASIK. It uses a special device to precisely measure the eye's unique irregularities and variations as well as your need for corrective lenses. This procedure has been compared to taking a fingerprint of the eye. You may benefit from this customized approach.

Wavefront measuring devices, called "analyzers" or "aberrometers," create a precise map of the eye. It is very detailed and records subtle distortions in your eye's visual system. Using this map, the excimer laser can be programmed to correct for these measured distortions, giving you clearer vision than was possible before with conventional treatments.

With your chin resting on the aberrometer, you will be asked to stare past what is called a target light. A targeted beam of light will be sent through your eyes and will focus on the retina. A sensor will measure the irregularities in the wavefront pattern of the light as it emerges from your eye. Using wavefront technology before performing LASIK can help your ophthalmologist (Eye M.D.) enhance the outcome of your surgery by correcting the unique visual distortions present in your eye.

About LASEK

About LASEK

If you have thin corneas and are not a candidate for laser-assisted in situ keratomileusis, or LASIK (a corneal refractive procedure that requires the creation of a partial-thickness flap before the cornea is sculpted with a laser), laser epithelial keratomileusis (LASEK) may be a good option for you.

LASEK is usually performed as an outpatient procedure using topical anesthesia with eyedrops. Your ophthalmologist (Eye M.D.) uses an alcohol solution to loosen and peel back the epithelium, the outermost layer of the cornea, to expose the corneal tissue beneath it. A cool excimer laser is used to permanently reshape the cornea, and the epithelium is either placed back into position, where it will self-adhere, or is removed completely, in which case the epithelium heals inward from the corneal periphery in just a few days.

Reshaping the cornea helps focus light directly onto the retina to produce clearer vision. After the procedure, a transparent "bandage" contact lens is placed on the cornea to promote healing.

About Epi-LASIK

If you have thin corneas and are not a candidate for laser-assisted in situ keratomileusis, or LASIK (a corneal refractive procedure that requires the creation of a partial-thickness flap before the cornea is sculpted with a laser), epithelial LASIK(epi-LASIK) may be a good option for you.

Epi-LASIK is usually performed as an outpatient procedure using topical anesthesia with eyedrops. Your ophthalmologist (Eye M.D.) uses a highly specialized type of cutting device, called an epikeratome, to precisely separate the thin epithelial flap -- much thinner than a LASIK flap -- from the rest of the cornea. Once your ophthalmologist separates the epithelium from the rest of the cornea, the thin sheet of epithelial cells is lifted to one side. After the cool beam of an excimer laser is used to permanently reshape the cornea, the thin sheet is then either moved back into place where it will self-adhere, or it is removed completely, in which case the epithelium heals inward from the corneal periphery in just a few days.

Reshaping the cornea helps focus light directly onto the retina to produce clearer vision. After the procedure, a transparent "bandage" contact lens is placed on the cornea to promote healing.

About Photorefractive Keratectomy (PRK)

Photorefractive Keratectomy

Photorefractive keratectomy (PRK) is one of several refractive surgery procedures used by ophthalmologists (Eye M.D.s) to permanently change the shape of the cornea to improve the way it focuses light on the retina.

PRK is an outpatient procedure performed with topical anesthetic eyedrops. It takes only about 15 minutes. The epithelium, the outer cell layer of the cornea, is removed with a blade, alcohol, or a laser. An excimer laser, which produces ultraviolet light and emits high-energy pulses, is used to remove a thin layer of corneal tissue. Your ophthalmologist guides the laser with a computer, and the laser beam sculpts the surface of the cornea. By breaking the bonds that hold the tissue molecules together, your cornea is reshaped, which corrects your refractive error and eliminates or reduces the need for eyeglasses or contact lenses. Because no incisions are made, the procedure does not weaken the structure of the cornea.

Immediately following surgery, the eye is patched or a "bandage" contact lens is placed on the eye. Vision is blurry for several days following PRK. It may take a month or longer to achieve your best vision. You may need to use medicated eyedrops for up to three months.

Possible complications of PRK surgery include undercorrection, overcorrection, poor night vision, and corneal scarring. Permanent vision loss is very rare. In recent studies monitored by the U.S. Food and Drug Administration, 95% of eyes were corrected to 20/40, the legal limit for driving without corrective lenses in most states.

To be a candidate for the procedure you must have a stable and appropriate refractive error, be free of eye disease, be at least 18 years old, and be willing to accept the potential risks, complications, and side effects of PRK.

About Phototherapeutic Keratectomy (PTK)

The cornea is the smooth, clear window of the eye in front of the colored iris that helps bend light rays so they focus directly on the retina, the light-sensing layer of cells at the back of the eye. If the corneal surface is rough or cloudy, the rays of light do not focus properly on the retina and images are blurry. Until recently, ophthalmologists (Eye M.D.s) treated rough corneas by scraping them smooth with a surgical blade, while cloudy corneas required a partial or full corneal transplant. Now, phototherapeutic keratectomy (PTK) is an option.

PTK is an excimer laser surgical procedure that removes roughness or cloudiness from the cornea by using a cool beam of light to evaporate tissue. The principal advantage of laser surgery over conventional surgery is that the laser is able to create a smoother corneal surface than a blade and smaller amounts of tissue can be removed.

Potential complications after PTK include poor wound healing, excessive corneal flattening resulting in farsightedness, and irregular astigmatism or poor vision that cannot be corrected completely with glasses.

About Conductive Keratoplasty (CK)

Conductive keratoplasty (CK) is a minimally invasive thermal refractive procedure used to correct mild to moderate farsightedness in people over age 40. With CK, your ophthalmologist (Eye M.D.) uses a tiny probe that releases controlled amounts of radiofrequency (RF) energy to apply heat to the peripheral portion of the cornea. The heat then causes the sides of the cornea to shrink and to tighten like a belt, increasing the steepness of the central cornea and increasing its optical power. This refocuses the light rays on the retina and improves vision.

CK can also be used to achieve "monovision." With monovision, CK can be used to improve close-up vision in a presbyopic eye that has good vision but has difficulty focusing up close. To maintain good distance vision, usually only one eye (the non-dominant eye) is set to near-focus vision, while the other is left alone or set at good distance vision. It may be a good idea to try monovision with a special contact lens or eyeglass prescription before opting for surgery. CK does not offer permanent correction; for some patients, farsightedness may return over time.

Monovision for Presbyopia

Many people use reading glasses to correct presbyopia, the age-related loss of close-up focusing ability. They use their eyeglasses for reading and other close work, taking them off when looking at objects that are farther away, or they use bifocals for clear distance and near vision.

Standard refractive surgery procedures do not correct presbyopia. Monovision is a specialized refractive surgery technique that enables one eye to focus at close proximity, while the other eye is left untreated or, if needed, treated for clear distance vision. Having each eye focus at different distances can reduce or eliminate the need for eyeglasses or contacts. It may seem difficult to get used to this, but about six to eight weeks after the monovision procedure, the brain is able to adjust to the two eyes' different focusing ability. Usually, this surgery is performed only after a successful trial of monovision using glasses or contact lenses.

The refractive procedures most commonly used to treat presbyopia are laser-assisted in situ keratomileusis (LASIK) and conductive keratoplasty (CK).

Conductive keratoplasty is a minimally invasive thermal refractive procedure. Your ophthalmologist uses a tiny probe that releases controlled amounts of radio frequency (RF) energy to apply heat to the peripheral portion of the cornea. The heat then causes the sides of the cornea to shrink and to tighten like a belt, increasing the steepness of the central cornea and its optical power. This refocuses light rays on the retina and improves vision. Your ophthalmologist will use CK to correct your dominant eye for distance vision and leave your other eye slightly nearsighted.

In addition to these procedures, other refractive procedures may be used to correct presbyopia, including the following:

  • laser thermal keratoplasty (LTK)
  • scleral expansion bands (SEBs)
  • refractive lens exchange (RLE)
  • multifocal LASIK (presby-LASIK)

Be sure to discuss your options with your ophthalmologist to choose the best refractive procedure for your needs, if surgery is a good option to correct your presbyopia. It may be best to test monovision with contact lenses before you opt for refractive surgery to be sure you will be comfortable with the adjustment following surgery and will achieve the results you desire.

As with any surgery, there are certain risks associated with LASIK, CK, and other refractive procedures. Be sure to discuss these possible risks with your ophthalmologist.

About Intracorneal Rings (ICRs)

Intracorneal Rings

Intracorneal rings are plastic inserts placed in the cornea. The rings flatten the central cornea to correct low levels of myopia (nearsightedness). Unlike other refractive surgery procedures, ICR procedures can be reversed. When the inserts are removed, the cornea usually returns to its preoperative shape and vision is once again myopic.

The ICR procedure is generally performed on an outpatient basis, using eyedrops for anesthesia. It is a quick procedure and can take less than half an hour.

Research is being done on intracorneal rings for correcting presbyopia (farsightedness) and astigmatism. Rings have recently been used with success in treating corneal disorders such as keratoconus, irregular astigmatism, and progressive corneal thinning that follows other corneal refractive procedures.

Complications with intracorneal rings are rare but can include undercorrection, overcorrection, induced astigmatism, infection, glare, halos, and extrusion of the insert. Minimal scarring may also occur in the area of the rings.

About Refractive Lens Exchange & IOLS

Refractive Lens Exchange & IOLS

Today, many people choose to correct their refractive errors with techniques other than wearing eyeglasses or contact lenses. Surgeries like laser-assisted in situ keratomileusis, or LASIK, improve vision by permanently changing the shape of the cornea to redirect how light is focused on the retina. However, in certain cases, LASIK or other refractive surgeries to reshape the cornea may not be a patient's best option. In these cases, instead of reshaping the cornea, the eye's natural lens can be removed and replaced with an intraocular lens (IOL) with a procedure called refractive lens exchange (RLE).

IOLs are artificial lenses surgically implanted in the eye. These lenses help your eye regain its focusing and refractive ability. RLE can be used to correct moderate to high degrees of myopia (nearsightedness) and hyperopia (farsightedness). In many cases, it is especially useful in treating presbyopia, the inability to focus at near distances with age.

The most common type of implantable lens is the monofocal or fixed-focus lens. It helps you attain clearer vision at one distance. Note that eyeglasses or contact lenses are still required to see clearly at all ranges of distance.

Another type of IOL is the multifocal IOL. The multifocal IOL has several rings of different powers built into the lens. The part of the ring you look through will determine if you can see clearly at far, near, or intermediate distances.

A third type of IOL is the accommodative IOL. This IOL has a hinge designed to work with your eye muscles, allowing the lens to move forward as the eye focuses on near objects and backward as the eye focuses on distant objects. Other styles of accommodative IOLs are currently being developed.

Implanting an IOL takes about 20 minutes in an outpatient procedure much like cataract surgery. In addition to a preoperative eye exam, the eye surgeon takes certain measurements of the eye. Your eyes are then numbed with topical or local anesthesia. A few small incisions are made at the edge of the cornea. Then a small ultrasound instrument is inserted into the eye to break up the center of the eye's natural lens. The lens is vacuumed out through one of the incisions. The IOL is usually folded and then inserted through the same incision. These incisions are usually self-sealing, requiring no stitches.

Once implanted, multifocal and accommodative IOLs allow you to focus on near or distant objects. You will probably have to take an antibiotic and steroid eyedrop for several days after the procedure, and you will need to wear an eye shield at night for one week to protect the eye.

Some advantages of refractive lens exchange are that unlike other forms of refractive surgery, RLE can be used to treat people with dry eye, thin corneas, or high refractive error. In addition, if you have RLE, you will never develop cataracts, as the natural lens is removed.

Risks associated with implanting IOLs include overcorrection or undercorrection, infection, increased "floaters" or retinal detachment, dislocation of the implant, halos and glare, dry eye, decreased contrast sensitivity, clouding of a membrane behind the IOL (this requires a quick laser procedure to remove it), and loss of vision.

You should consult with your ophthalmologist to determine if refractive lens exchange is the best treatment for your specific condition and vision needs. If you are considering RLE, you should discuss which IOL might be best suited for you.

Thin corneas and the risk of ectasia

Ectasia is a condition that occurs when the cornea is so thin that intraocular pressure (IOP) leads to instability and bulging of the cornea. This causes blurring, myopia, and irregular astigmatism.

During laser-assisted in situ keratomileusis (LASIK), the surgeon creates a flap in the outer layer of your cornea and uses the laser to remove some of the lower corneal tissue that is exposed when the flap is moved aside. If your corneas are thinner than normal, you may be at an increased risk for ectasia following LASIK, especially if you require additional LASIK procedures to fine-tune your vision correction. It is even possible (though extremely rare) for ectasia to develop following photorefractive keratectomy (PRK), a surface laser procedure that does not involve creating a corneal flap.

If you have thin corneas, you may not be a good candidate for LASIK. Ask your ophthalmologist (Eye M.D.) if alternative refractive procedures such as epi-LASIK or PRK might offer you a better chance at improved vision without any unnecessary risk of adverse side effects.

» View All Procedures

» View Frequently Asked Questions