PRK

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PRK: The Original Laser Eye Surgery By Liz Segre; Segre; reviewed by Charles Slonim, MD PRK (photorefractive keratectomy) once was the most common refractive surgery procedure  before LASIK  was  was developed as a more popular alternative. Both PRK and LASIK are grouped under the umbrella "laser eye surgery," bu butt each is a little different when it comes to advantages and disadvantages. LASIK patients have less discomfort and obtain good vision more quickly — whereas, improvement with PRK is gradual and takes days, weeks or even months. But many surgeons  prefer PRK in circumstances such as when patients have thin corneas. corneas. PRK was invented in the early 1980s. 1 980s. The first FDA approval FDA approval of a laser for PRK was in 1995,  but the procedure was practiced in other countries for years. In fact, many Americans had the surgery done in Canada before it was available in the United States. PRK is performed with an excimer laser, which uses a cool ultraviolet light beam to precisely remove ("ablate") very tiny bits of tissue from the surface of the cornea in order to reshape it. When you reshape the cornea co rnea in the right way, it more precisely focuses light into the eye and onto the retina, retina, providing clearer vision than before. Both nearsighted and nearsighted and farsighted people farsighted people can benefit from PRK. With nearsighted people, the goal is to flatten the too-steep cornea; with farsighted people, a steeper cornea is desired. Also, excimer lasers can correct astigmatism astigmatism,, by smoothing an irregular cornea into a more normal shape.

Before PRK Surgery If you are considering PRK, your first step is to choose a surgeon. surgeon. Your doctor will examine your eyes to determine exactly what kind of vision correction you need and how much laser ablation is required. A corneal topographer will be used; this is an instrument that measures the curvature of the front of your eye and creates a kind of "map" of your cornea. No one has a perfectly rounded cornea, and the topographer will display the corneal irregularities and the actual steepness or flatness that the surgeon must address. Also, your eye doctor   will will ask you about medical conditions you may have. Some conditions might disqualify you altogether as a PRK candidate; others may mean a postponement of the  procedure or special care afterward.

 

During PRK Surgery PRK is an ambulatory procedure; you walk into the surgery center, have PRK and walk out again. In fact, the actual surgery usually takes only a few minutes, and you're awake the whole time. Occasionally, the doctor will give you a mild oral sedative beforehand. Most people don't painwill during Your eyesand arethen anesthetized drops prior to the procedure. Thefeel doctor havePRK. you lie down, will makewith surespecial your eye is positioned directly under the laser. (One eye is operated on at a time.) A kind of retainer is placed under your eyelids to keep them open — normally, this is not uncomfortable. The doctor uses a computer to adjust the laser for your particular prescription. You will be asked to look at a target light for a short time while he or she watches your eye through a microscope to make sure it remains in the correct position while the laser sends pulses of light to your cornea that painlessly remove the tissue. It's important to keep your gaze fixated on that target light in order to get the best results. The laser machine will make a steady clicking sound as the laser reshapes your cornea, and you may notice a slight odor during the tissue removal. Don't worry, that's normal. The higher your prescription, the more time the surgery will take. But even for high  prescriptions, the laser treatment treatment generally takes less than a minute. The surgeon has full control of the laser and can turn it off at any time. After the procedure is finished, you will rest for a little while. If you're having both eyes done the same day, da y, the surgeon will probably do the other eye after a short period of time. Many people choose to have their second eye done a week or two after their first eye.

After PRK Surgery As with any kind of eye surgery, surgery, it's important that you follow your doctor's instructions to the letter. Get proper rest, use all prescribed medications as directed and call your doctor immediately if you suspect a problem. Immediately after PRK, the doctor will have you rest for a bit, then you can go home (someone else must drive). At home, you should relax for at least a few hours. You may be able to go to work the next day, but many doctors advise a couple of days of rest instead. They also recommend no strenuous exercise for up to a week, since this can traumatize the eye and affect healing. Avoid rubbing your eye (your doctor will tell you how long). Your surgeon or general eye doctor  will examine your eye the day after surgery and several times thereafter to make sure the epithelium is epithelium  is healing properly. You probably will wear a special "bandage" contact lens, use antibiotic drops for a few days and apply ap ply anti-inflammatory drops for several weeks. Your

 

surgeon also will prescribe medication to reduce eye discomfort that you are likely to experience the first few days after PRK surgery.

PRK and LASIK outcomes typically outcomes  typically are similar. Most people achieve 20 20/20 /20 or better vision with PRK (also true of LASIK). Some may achieve only 20/40 or not quite as good. In fact, 20/40 is fairly good vision — considered good enough for driving in most states. Some patients still may need eyeglasses or eyeglasses or contact lenses following lenses following laser vision correction, though their prescription level will be much lower than before. be fore. Postoperative PRK and LASIK complications complications can  can include infection and/or night glare (starbursts or halos that are most noticeable when you're viewing lights at night, such as while you're driving). Even if you see 20/20 or better on an eye chart after chart after laser eye surgery, you still may need reading glasses once glasses  once you hit your 40s. This is because the eye's lens becomes lens becomes less flexible with age (a condition called presbyopia called presbyopia), ), reducing your near vision. Your distance vision probably will remain crisp, but seeing up close will be more difficult. However, researchers are studying different approaches to presbyopia to  presbyopia surgery. surgery. So it's possible that you could have one of these new presbyopia-correcting procedures p performed erformed later to restore your near vision, once they are FDA-approved. FDA-approved. These are important topics to discuss with your surgeon before making the decision to have PRK  surgery.

Photorefractive Keratotomy (PRK) Eye Surgery        

Int Introdu roduco con n he advantages advantag es of PRK? What are tthe What are tthe he disadvantages disadvan tages of PRK? PR K? potenal tenal side eects e ects of PRK? PRK ? What are the po prepare are for PRK PR K surgery? surger y? How do I prep happenss during the PRK procedure pro cedure? ? What happen expect pect aer PRK PR K surgery? surgery ? What should I ex Will I sll need reading glasses to correct presbyopia aer I have had PRK?

Introduction

Photorefractive keratectomy, or PRK, is a type of laser eye surgery used to correct mild to moderate nearsightedness , farsightedness and/or astigmatism .

 

All laser vision correction surgeries work by reshaping the cornea, or clear front part of the eye, so that light traveling through it is properly focused onto the retina located in the back of the eye. There are a number of different d ifferent surgical techniques used to reshape the cornea. During PRK, an eye surgeon uses a laser to reshape the cornea. This laser, which delivers a cool pulsing beam of ultraviolet light, is used on the surface of the cornea not underneath the ccornea, ornea, as in LASIK. What Are the Advantages of PRK?

PRK is highly accurate in correcting many cases of nearsightedness. Approximately 80% of PRK patients have 20/20 2 0/20 vision without glasses or contact lenses one year after the surgery; 95%-98% have 20/40 or better without glasses or contacts. What Are the Disadvantages of PRK?

Disadvantages of PRK include: 







Mild discomfort, including minor eye irritaon and watering, for 1 to 3 days following the procedure. It is expensive, typically cosng as much as LASIK, around $2,200 to $2,250 per eye. Somewhat longer me to best uncorrected vision (best vision is vision aained using glasses or contacts) typically paents are 80% at 1 month aer surgery, and 95%-100% by 3 months aer surgery. LASIK, in contrast, corrects vision much faster. The outcome is not completely predictable and some paents may sll require glasses.

What Are the Potential Side Effects of PRK?

Many PRK patients experience some discomfort in the first 24 to 48 hours after surgery and almost all experience sensitivity to light. Within the first six months after surgery, other potential side effects may include:   

Loss of best vision achieved with glasses Seeing a minor glare, this can be permanent, depending on a paent's pupil size in dim light. Mild halos around images

How Do I Prepare for PRK Surgery?

Before your PRK surgery you will have met with a coordinator who will discuss with you what you should expect during and after the surgery. During this session your medical history will be evaluated as well as have your eyes tested. Likely tests will include measuring corneal thickness, refraction, and pupil dilation. Once you have gone through your evaluation, you will meet the surgeon, who will answer any further questions you may have. Afterwards, you can schedule an appointment for the PRK procedure.

 

If you wear rigid gas permeable contact con tact lenses, you should not wear them starting three weeks  before the date of your surgery. Other types of contact lenses shouldn't be worn for at least three days prior to surgery. Be sure to bring your glasses so your prescription can be reviewed. On the day of your you r surgery, eat a light meal before coming and take all of your prescribed medications. Do not wear eye makeup or have any bulky accessories in your hair that will interfere with positioning your head under the laser. If you y ou are not feeling well that morning, call ca ll the doctor's office to determine whether the procedure needs to be postponed. What Happens During the PRK Procedure?

The PRK procedure is done under local anesthesia and takes a maximum of about 10 minutes to do both eyes. During PRK, an a n eye surgeon uses a laser to reshape the cornea. This laser, which delivers a cool pulsing beam of ultraviolet light, is used on the surface of the cornea not underneath the cornea, as in LASIK. What Should I Expect After PRK Surgery?

Most of the time, a bandage contact lens will be applied immediately after the procedure. p rocedure. This contact lens is usually worn for the first 3 to 4 days to allow the surface of the eye to heal. You should expect to visit your eye doctor at least a few times during the first 6 months after surgery, with the first visit being the day after surgery. Once the surface of the eye is healed, the bandage contact lens is removed. Your vision may fluctuate between clear and blurry for the first few weeks following surgery and you may need to wear glasses for night driving or reading until your vision stabilizes. Your eyes will be dry even though they do not feel that way. Your doctor will give you prescription eye drops to prevent infection and keep your eyes moist. These drops may cause a slight burn or momentary blurring of your vision upon using them. Do not use any drops not approved by your ophthalmologist. Your vision will gradually improve, and usually will be good enough to allow you y ou to drive a car within two to three weeks following surgery. Keep in mind, however, that your best vision may not be obtained for up to 6 weeks to 6 months following surgery. Will I still need reading glasses to correct presbyopia after I have had PRK?  

Presbyopia happens in all patients over 40 and can be corrected with reading glasses or with laser  refractive surgery doing something called monovision, where using contact lenses, the nondominant eye is corrected for reading and the dominant eye is corrected for distance. PRK is not used to correct presbyopia. Reviewed by the doctors at The Cleveland Clinic Cole Eye Institute. Edited by Charlotte E. Grayson, MD, WebMD, MD, WebMD, November 2004. Portions of this page copyright © The Cleveland Clinic Clinic 2000-2004  2000-2004

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