Over 60 million Americans suffer from nearsightedness, or myopia. A person is considered nearsighted when the eye has too much focusing power. This occurs when the eyeball is either too long or the cornea (the clear front cover of the eye) is too steep to allow light to focus directly on the retina (the “film” at the back of the eye). Instead, light focuses in front of the retina, causing distant images to appear blurry. A minus power lens in the form of eyeglasses or contact lenses is needed to subtract focusing power from the eye.
Hyperopia is a condition where light rays entering the eye are focused behind the retina instead of directly on it, as in the normal eye. It may be present in childhood but does not usually become apparent until people are in their late 20s or 30s when they can no longer see up close. When these patients reach their 40s or 50s, they may start having difficulty seeing distant objects as well.
Astigmatism is a condition that occurs when the cornea or lens is steeper on one axis than another, similar to a football or the back of a spoon, instead of being completely spherical or round like a basketball. Light entering the cornea focuses on more than one point within the eye, resulting in blurred vision. Astigmatism is either regular when steep and flat axes are 90 degrees apart, or irregular when they are not separated by 90 degrees.
Literally “old vision,” presbyopia is part of the natural aging process of the eye, affecting most people by age 40. Normally, when a close object is viewed, the lens will change shape or “accommodate” to focus light on the retina. With presbyopia, the lens cannot sufficiently reshape and glasses are required for close viewing. When someone has laser vision correction for nearsightedness and he or she is already presbyopic (40+ years of age), correction for reading will still be needed, which typically means wearing the store-bought magnifying glasses.
A diopter is the unit of measure used in optics which determines the refractive power of a lens. A minus sign in front of the number indicates nearsightedness and a plus sign indicates farsightedness.
They can be corrected with glasses, contact lenses or surgery.
A procedure called orthokeratology has been available for many years, where a series of progressively flatter gas permeable hard contact lenses are used to gently and gradually re-shape the surface of the cornea. When the cornea has reached its desired correction, a retainer contact must be worn for several hours per day (normally at night, while sleeping) to prevent the cornea from returning to its original shape. Orthokeratology doesn’t make permanent changes to the eye; if the patient stops wearing the lens, the eyes will revert to their former state within 1 to 4 weeks.
These are a group of surgical procedures designed to permanently reduce or eliminate the need for corrective eyewear to see distant objects. They include laser assisted in-situ keratomileusis (LASIK), photorefractive keratectomy (PRK), radial keratotomy and astigmatic keratotomy (RK/AK), laser thermal keratoplasty ( LTK), and conductive keratoplasty (CK). While these procedures can be very effective, they can only improve vision problems that are correctable with glasses or contact lenses.
These are refractive procedures performed with an excimer laser. The excimer generates ultraviolet light of a specific wavelength (193 nanometers) by sending high-voltage electrical energy through a cavity containing argon fluoride gas. The beam that is emitted has enough energy to break the bonds between the molecules that make up the tissue on your eye’s surface (the cornea). Because it is a photochemical and not a heating process, the surgeon is able to sculpt very precise amounts of corneal tissue without any damage to neighboring tissue.
The excimer laser was developed at IBM to etch computer microchips. Its extreme precision with negligible damage to adjacent tissue made it a very attractive tool for other applications. In 1983, ophthalmologist Stephen L. Trokel, M.D., in cooperation with physicist R. Srinivasan, applied it to corneal tissue in a New York laboratory. The first sighted eye was treated with the excimer laser on January 14, 1987.
LASIK (laser in-situ keratomileusis) and PRK (Photorefractive Keratectomy)
In both procedures, a specially-trained ophthalmologist uses the computer-guided excimer laser to gently remove a thin layer of tissue from the cornea to achieve a desired correction. Prior to the procedures, drops are placed in the eye to numb it (similar to what an eye doctor uses to check eye pressure for a glaucoma test) and an instrument called a speculum is placed in the eye to prevent the patient from blinking. In PRK, the surgeon first removes the surface cells of the cornea using the laser before sculpting the underlying tissue, and then surface cells regenerate over the next 48 to 72 hours under a bandage contact lens. No needles are used, and the patient does not normally experiences any pain. In LASIK, a femtosecond laser is used to separate a thin layer of the corneal tissue, which is left attached on a hinge. The excimer laser is then used to sculpt tissue from the corneal bed and the flap is floated back into place, reattaching without the need for sutures.
Most patients are in the laser suite for no longer than 10 minutes. The actual laser treatment time takes just 15 to 90 seconds, depending on the degree of correction required. Total time at the center on the day of the procedure will be about an hour.
Because the healing occurs in the interior of the cornea, no regrowth of surface cells is necessary. The corneal flap protects the treated area and there is usually little, if any, post-op discomfort. Visual rehabilitation is much quicker than other refractive surgical procedures, and regulation of the healing process with long term post-op drops is unnecessary since the center of the cornea tends to have much less of a healing reaction than the surface.
The laser is used to reshape the regions where the cornea is high or elevated. Here’s a simple illustation to explain what’s done: With astigmatism, the cornea is shaped like a football. The laser sculpts the surface of the cornea into the shape of a baseball or basketball to correct for the astigmatism.
Radial Keratotomy (RK) is a surgical procedure that can also correct nearsightedness by changing the shape of the cornea. Microscopic incisions of 90 percent depth, placed in a radial pattern like the spokes of a wagon wheel, reshape and flatten the central cornea, allowing light to focus more precisely on the retina. The length and number of incisions determine the effect of the surgery. Patients with less than three diopters of nearsightedness and stable prescriptions are the best candidates.
Another alternative to LASIK and PRK eye surgery that has recently been approved by the FDA are implantable lenses known as refractive intraocular lens implants (RIOLs). Usually reserved for patients with extreme myopia, RIOLs are surgically placed either between the cornea and the iris or just behind the iris, to enable light to focus properly on the retina for clearer vision.
A variation of RK, known as astigmatic keratotomy (AK), is an effective means of reducing astigmatism. It involves making incisions in an arc-like or segmental fashion parallel to the white of the eye (where the cornea is steep) to reshape the cornea from an oval shape into a spherical shape.
In the past, automated lamellar keratectomy (ALK) was used in which a thick layer of the cornea was folded back with a microkeratome. Pressure inside the eye causes the corneal bed to steepen, the opposite of what occurs in LVC. The cap was placed back into position without the removal of additional tissue. Although it has been shown to effectively reduce or eliminate farsightedness in the +1.00 to +5.00 range, enough cases of corneal instability have been reported nationwide that this procedure has fallen out of favor. Now, LASIK for hyperopia is considered by most to be the best option. Conductive Keratoplasty (CK) uses a needle-like probe to deliver radio-frequency energy to the corneal collagen in a ring of individually placed spots to steepen the cornea. Farsighted patients with a prescription between +0.75 to +3.25 and no more than 0.75 diopters of astigmatism are the best candidates for this procedure. Because of mild regression and a lack of long-term results, the procedure has been labeled as temporary.
The results are quite remarkable. In the U.S. clinical trials for the Wavelight Allegretto for nearsightedness, 100 percent of the patients experienced improved, uncorrected vision six months after the treatment; 98 percent were returned to 20/40 sight or better (the “driving standard” in most states) and were able to perform most activities without glasses or contacts; 88 percent saw at least 20/20; and an amazing 60 percent saw better than 20/20.
Yes, both the PRK and LASIK procedure have been FDA-approved to be safe and effective. After extensive testing, the U.S. Army has also approved laser vision correction for American soldiers.
The majority of all nearsighted Americans are potential candidates for the laser treatment. Patients must be at least 18 years of age, have mild to moderate nearsightedness with a stable prescription, and have no ocular or health issues. The best candidates tend to be people who are dissatisfied with their glasses or contact lenses and are motivated to make a change, either for occupational or lifestyle reasons. Although a patient’s prescription may make him or her a suitable candidate for laser vision correction procedure, it is very important that the patient have the appropriate level of expectations regarding the outcome of the procedure. Although uncorrected post-op vision (after healing) is usually excellent, no one can guarantee a 20/20 vision.
The best candidates for laser vision correction can identify with the following statements:
A person is probably not a good candidate for laser vision correction if he or she identifies with the following statements:
A person is not a good candidate for laser vision correction if he or she is under 18 years of age, unwilling to commit to follow-up care instructions, and if any of the following conditions are present:
The corneal thickness measurement is a very important test and can be the major limitation for LASIK. This measurement is a standard test at the Atlanta Vision Institute. In these situations, PRK is an alternative to LASIK.
The only way to determine if someone is a good candidate is with a full eye exam. A corneal injury may or may not preclude someone from the surgery. It all depends on the size and type of injury.
There is very mild discomfort during the PRK procedure. Afterwards, some patients experience a gritty sensation, burning, tearing or light sensitivity for the first 2 to 3 days. During the LASIK procedure, there is mild discomfort and no pain. Following the procedure, patients may experience some scratchiness, burning and tearing for 2 to 3 hours.
Most patients undergoing LASIK and PRK prefer to have both eyes treated on the same day since it is more convenient for them. However, this is a decision made entirely by the patient and the doctor.
Yes. Dr. Ashraf asks patients to fixate on the red blinking light in the microscope during the procedure. Keep in mind the whole treatment happens rather quickly. With Dr. Ashraf’s experience and the speed of the Wavelight Allegretto laser, the entire LASIK procedure is completed in less than 10 minutes.
The Wavelight Allegretto laser has a tracking device, which detects and compensates for small movements by keeping the laser beam precisely centered over the treatment area. This ensures patients the highest level of precision, comfort and safety.
Most people can return to their normal activities the day after the LASIK procedure, and that includes driving and going to work.
In PRK, because the laser removes tissue from the surface of the eye, the body will attempt to fill in the defect much like it would for a cut on the hand. Since corneal tissue has different healing properties, the process can normally be regulated with the use of topical steroid drops, which patients may be required to use over a one-month period. In LASIK, these drops are only used for a week. These drops rarely cause any problems. However, the eyes should still be monitored on a monthly basis to fine-tune the drop dosage and check for any unwanted side effects, such as delayed or rapid healing and elevation in eye pressure (glaucoma). Antibiotic drops are also used for about a week with both procedures. Please see our post operative instructions.
Plan on about three short visits in the first three months after surgery. Even if the patient is seeing well, there are things that must be monitored during the first few months in order to ensure the best possible vision outcome.
Showering or bathing in a standard shower or bathtub is okay as soon as one day after the procedure. Still, patients should avoid getting soap or water in their eyes for at least a week following eye surgery. Other types of water activities - namely immersing in a pool, a jacuzzi or ocean water - should also be avoided for at least a week.
We recommend buying new mascara after surgery to avoid infection and to wait 1 to 2 weeks before using eye makeup.
Patients may resume driving when they feel comfortable with their vision. The majority of patients are able to drive on their own on the day following LASIK. With PRK, it usually takes about 4 to 5 days to feel comfortable.
Exercising can resume when the patient is ready. However, it is important not to get sweat in the eyes, to keep the hands clean and away from the eyes, and to avoid rubbing the eyes for the first few weeks after surgery. Swimming should also be avoided for at least two weeks.
The vast majority of patients have no serious side effects. The most common complaint after laser vision correction is dry eyes. Patients at particular risk are those who have dry eyes prior to vision correction. Dr. Ashraf will perform a complete eye exam prior to laser surgery and if called for, he may initiate dry eye treatments prior to the procedure for some patients. The majority of dry eye cases usually resolve within a few weeks following surgery. Another complaint after surgery is the “halo” effect and some glare at night around lights. However, these problems are no worse than what most contact lens and eyeglass wearers often experience and the majority of patients function without any visual impairment at night. Using the Wavelight Allegretto laser, we can expand the treatment areas, thereby reducing the risk of side effects in patients with larger pupils.
As with any surgery, complications could potentially occur. The good news is that after over 3 million laser vision correction procedures have been performed in the United States, no cases of blindness have been reported as a result.
While more comfortable and yielding quicker rehabilitation of vision, LASIK is technically more difficult to perform than PRK. There is an extra step involved: the creation of the corneal flap. This is rarely associated with any considerable or permanent vision loss. However, there are occasional circumstances which could cause flap complications. Fortunately, most of these can be corrected with additional procedures.
Since being approved by the FDA in 1998, nearly 700,000 people undergo LASIK each year. Surgeons have been performing the procedure for over 15 years and over 30 million procedures have been performed worldwide. To date, very few sight-threatening complications have occurred. LASIK is generally a very safe and effective vision correction option for those who qualify.
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