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Wavefront-Guided LASIK
LASIK (laser in situ keratomileusis) is an outpatient surgical procedure that uses a laser to reshape the eye's cornea — the clear window at the front of the eye — to correct refractive errors, or problems with the way the eye focuses light. Millions of people today have had their refractive errors such as nearsightedness, farsightedness and astigmatism corrected with LASIK.
With LASIK, your ophthalmologist (Eye M.D.) creates a thin flap in the corneal tissue. After folding back the flap, your ophthalmologist uses a laser, preprogrammed with measurements specific to your eye, to sculpt the exposed corneal tissue. Once the cornea has been reshaped, the flap is put back into position, where it adheres naturally on its own.
One of the keys to a successful LASIK procedure is the measurement your ophthalmologist takes to determine your refractive error. Now an enhanced version of LASIK is available called wavefront-guided custom laser surgery, or wavefront-guided LASIK. Wavefront-guided LASIK uses a special device to precisely measure the unique irregularities and variations in your eye. If wavefront-guided LASIK is an option for you, you may benefit from this customized approach to refractive surgery that results in improved quality of vision compared to a traditional approach.
How Wavefront-Guided LASIK Works
To understand how wavefront works, it's important to understand how your eye focuses light.
A perfect cornea allows light entering the eye to be focused evenly through the pupil and then fine-tuned by the eye's natural lens so that light rays fall precisely onto the retina.
Small imperfections in the eye cause some light to travel through the eye at different angles. It is these imperfections that can cause the light to strike the retina in different places. As a result, you may experience symptoms like halos, glare, starbursts or ghosting of images.
Wavefront measuring devices create a "map" of your eye. The wavefront map is very detailed: instead of a general outline, like the map of a country, it is more like a topographical map that records every subtle curve and dip. In fact, you might hear wavefront described as a "fingerprint of your eye," because it measures tiny, subtle variations in the eye that are as unique as your fingerprints.
Measuring your eye with wavefront technology before performing LASIK can help your ophthalmologist enhance the outcome of surgery, with fewer visual side effects and improved quality of vision following the custom procedure as compared to a conventional approach.
What Happens During the Wavefront Measurement?
Your ophthalmologist will map both of your eyes using a wavefront scanner, called an analyzer or aberrometer. This device produces a very precise, detailed map of light rays as they travel through your eye, highlighting imperfections in your vision.
You will place your chin in the chin rest of the aberrometer, and you will be asked to stare past what is called a target light. To ensure correct measurement, be sure to stare past the target light, not directly at it. Your eye's focus should be as relaxed as possible.
A targeted beam of light will be sent through your eye and focused on the retina. As the wave of light rays are reflected back from the retina through the eye's vitreous, lens, pupil and cornea, a sensor will measure the irregularities in the wavefront pattern of light as it emerges from your eye. Using this measurement, the wavefront computer creates an accurate, three-dimensional map of your eye's visual system, including specific imperfections in the cornea. This wavefront data will be used to program the excimer laser, allowing your ophthalmologist to customize the reshaping of your cornea.
A wavefront map of an eye with no visual errors appears to have a flat surface because all of the light rays travel evenly through the eye.
A wavefront map of an eye with visual imperfections (aberrations) appears curved or distorted because some light rays reach the retina before others or strike different points on the retina.
What Are the Benefits of Using Wavefront Technology?
Wavefront-guided LASIK not only corrects the eye's nearsightedness, farsightedness or astigmatism — much as glasses, contacts or conventional refractive surgery do — but it also reduces the possibility that higher-order aberrations may cause glare, poor night vision, haloes, and blurry images after surgery. Higher-order aberrations are distortions in your vision that cannot be corrected with glasses and contacts and can only be measured with wavefront analysis.
One of the main differences between conventional LASIK and wavefront-guided LASIK is that with conventional LASIK, the laser tends to use the same power treatment over the center and sides (periphery) of the cornea, whereas wavefront technology modifies treatment over the peripheral cornea to further improve optical quality. For people with larger pupils, particularly under low light conditions, such as dusk or nighttime, quality of vision is generally improved.
It is important to understand that wavefront-guided LASIK may not be suitable for everyone. Your ophthalmologist can determine if wavefront-guided LASIK is an option for you. If you are a candidate for this advanced procedure, you'll join a growing number of people who are enjoying a better quality of corrected vision.
LASIK — Is It For You?
Background
Laser in situ keratomileusis (LASIK) is a surgical procedure to reduce nearsightedness (myopia), farsightedness (hyperopia) and astigmatism by reshaping tissue in the cornea, the clear covering of the front of the eye. It evolved from a variety of refractive surgery techniques including photorefractive keratectomy (PRK). In LASIK, an automated device called a microkeratome is used to create a thin flap in the cornea that is lifted; an excimer laser is then used to reshape the underlying corneal tissue and the flap is replaced over the treated area.
The Food and Drug Administration (FDA) first approved the excimer laser in 1995 for the PRK correction of nearsightedness and in 1998 for the LASIK correction of nearsightedness with or without astigmatism.
Is LASIK Safe?
In January 2002, the American Academy of Ophthalmology — The Eye M.D. Association — looked at a number of scientific studies and found that LASIK is safe and effective for correcting low-to-moderate nearsightedness and astigmatism. However, the Academy also found the results of LASIK are less predictable in eyes with moderate-to- high nearsightedness.
The Academy found serious complications resulting in permanent visual loss happen rarely with LASIK, but side effects such as dry eyes, nighttime starbursts and reduced ability to see in dim light occur more frequently. Your doctor should talk to you about the possible risks and side effects of LASIK.
Who Shouldn't Have LASIK?
LASIK is an excellent procedure for many, but not all people with refractive errors. Those who are not good candidates should not have the surgery. If you have any of the following conditions, you may not be a good candidate for LASIK:
Uncontrolled or advanced glaucoma Pregnant or breastfeeding Diabetes Some autoimmune disorders (e.g. rheumatoid arthritis, lupus, HIV/AIDS) Use of Prednisone pills or drops Dry eyes Irritation of the eyelids with itching and scaly skin Pupil size over seven millimeters Warped* or thin corneas Genetic or metabolic problems affecting the cornea * If you wear contact lenses, especially rigid lenses, before performing LASIK your doctor will examine you using a series of measurements to see if your corneas are warped. Your Eye M.D. may ask you to remove your rigid contact lenses for several weeks or months, and soft contact lenses for several days or weeks prior to examination to allow your cornea to return to its normal shape.
Is LASIK Better Than PRK?
LASIK has become more popular than PRK for a number of reasons, including:
Vision stabilizes sooner after surgery Less discomfort after surgery Faster improvement in vision Less corneal haze For people who need higher levels of correction, vision is more predictable and stable, and the corneas are clearer Shorter time on medication after surgery Enhancement procedure, if needed, is easier However, LASIK may not be the best procedure for you. Other procedures such as PRK may be better suited for you. Your doctor will work with you to determine which, if any, procedure is best for you.
Will LASIK Give Me 20/20 Vision?
It might, but even after LASIK, you may not be able to "throw away your glasses and contacts." Studies have shown that the majority of people — but not all — who have LASIK will come away with 20/40 vision or better without the need of glasses or contact lenses. Some people choose to have a second surgery, referred to as an enhancement, to further refine their vision and reduce their dependence on glasses or contact lenses. However, most people who have had LASIK will need reading glasses as they get into their 40s and 50s.
What Should I Do If I'm Considering LASIK?
Talk to an Eye M.D. to determine if you are a good candidate for the procedure. If you have any of the conditions mentioned earlier, you may not be. If your Eye M.D. determines that you are a good candidate, before setting a date for surgery, find out:
The possible risks and complications The experience of your surgeon The outcomes of the procedures performed by your surgeon The percent of patients returning for secondary procedures (enhancements) Whether your surgeon is using a laser approved by the FDA What is involved in after-surgery care Who will handle and be responsible for after-surgery care
Where Can I Get More Information?
Your Eye M.D. (ophthalmologist) is the best source of information on LASIK, as well as eye health and safety.
Other sources of information on LASIK include: National Eye Institute at 301.496.5248 or www.nei.nih.gov Food and Drug Administration at 301.827.4420 or www.fda.gov Federal Trade Commission at 1.877.382.4357 or www.ftc.gov Approved by: The Eye Health and Public Information Task Force September 2002 Revised November 2003
LASIK, laser assisted in situ keratomileusis, is an outpatient surgical procedure used to treat myopia (nearsightedness), hyperopia (farsightedness) and astigmatism by reshaping the cornea (the clear "window" at the front of the eye). LASIK, like any surgery, has risks that need to be carefully considered.
Risks
LASIK risk rates, types and degrees vary widely from person to person. The most common side effects of LASIK are:
Dry Eye
Changing and blurry vision
Light sensitivity and glare
Undercorrection or overcorrection
Nighttime haloes and starbursts
Temporary discomfort
For most people these side effects resolve or decrease with time.
Approximately 5 percent are undercorrected and return for enhancements.
Rare sight-threatening complications of LASIK are: 1
Corneal infection
Corneal inflammation
Permanent vision loss
Problems with the "flap" that is created (or made) in the cornea during surgery
Foreign matter under flap
Fortunately, for some people, the side effects wear off or can be improved with glasses, contact lenses or additional laser surgery.
Facts and Statistics
In clinical studies, serious complication rates vary between 0 percent and 5 percent. Approximately 5 percent to 10 percent of LASIK patients return for enhancements (additional procedures to help improve vision after the first surgery).
Should I Have LASIK?
If considering LASIK, it is important to understand that LASIK is surgery and that results cannot be guaranteed. Before making a decision about getting LASIK, make sure the surgeon fully explains the risks and benefits of the procedure. Those who expect perfect vision from LASIK may be disappointed.
Where Can I Get More Information?
Your Eye M.D. (ophthalmologist) is the best source of information on LASIK, as well as eye health and safety.