PRK (photorefractive keratectomy) and LASEK (laser epithelial keratomileusis) for nearsightedness
Surgery Overview
PRK (photorefractive keratectomy) and LASEK (laser epithelial keratomileusis) use a laser to reshape the cornea. By reshaping the cornea, these surgeries refocus the light on the retina.
With PRK, the top layer on the surface of the cornea (epithelium) is removed. Then the laser reshapes the cornea. The laser removes tissue from the cornea very accurately without damaging nearby tissues. The layer grows back during the healing process. PRK may be used to correct nearsightedness and astigmatism at the same time.
With LASEK, the surface layer of the cornea is loosened and pushed to the side. After the laser reshapes the cornea, the surface layer is placed back over the cornea.
A third surgery, epi-LASIK (epithelial laser in-situ keratomileusis) is similar to PRK and LASEK. With epi-LASIK, the surface layer over the cornea is lifted with a special machine. Like LASEK, the layer is replaced over the cornea after the laser reshapes the cornea.
PRK, LASEK, and epi-LASIK are sometimes called surface ablation. They are different from LASIK (laser in-situ keratomileusis) because they do not involve cutting flaps of the cornea.
What To Expect After Surgery
PRK and LASEK are outpatient procedures. They are done under local anesthesia in a surgeon's office or a same-day surgery center. The procedure takes about 30 minutes, most of which is spent preparing your eye and the laser. The actual treatment time is very short. Most treatments take a minute or less (treatment for farsightedness may take longer than a minute). The entire process may take about 2 hours, including preparation time, care right after the surgery, and paperwork.
After surgery, you may wear a patch or contact lens on the eye and get a prescription for pain medicine. Someone must drive you home and then back to the surgeon's office the next day. During this second visit, the surgeon will examine your eye and prescribe eyedrops to prevent infection and reduce inflammation. More follow-up visits are required, usually the next week and then throughout the first year after surgery.
- Recovery from PRK or LASEK is longer and more painful than recovery from either radial keratotomy (RK) or laser in-situ keratomileusis (LASIK). But you may return to your normal activities within a few days.
- Some people may have pain, aching or throbbing, or a feeling that there is something in the eye for 2 to 3 days after surgery.
- Your vision will be reduced for several days after surgery. Your vision may remain blurry for days to weeks after surgery. Do not drive until your vision has cleared.
- For 2 weeks after surgery, avoid vigorous sports, eye makeup, and activities that may get water in the eye. The surgeon may recommend that you shower before the surgery and then avoid showering for a day or two afterward to keep from getting water in the eye.
Unstable vision is common in the first 3 months after surgery and may last for up to 1 year. Your vision may vary slightly over the course of a day (although not to the point that you would need two pairs of glasses).
Why It Is Done
PRK and LASEK are similar surgeries and are performed for similar reasons.
The American Academy of Ophthalmology considers PRK safe and effective for mild to moderate nearsightedness. Specifically, the surgery has been approved for use in the United States in people ages 21 and older who have 1.5 to 7 diopters of nearsightedness. Most people with nearsightedness fall in this mild-to-moderate range.
PRK may not be appropriate for people who have more severe nearsightedness (high myopia), because the results are harder to predict, complications are more likely, and regression is more likely. Also, PRK may not be appropriate if you have keloids.
In general, for correcting nearsightedness over 3 diopters, both PRK and LASIK are considered more effective than radial keratotomy (RK).
PRK is an elective, cosmetic procedure that is done to correct nearsightedness in otherwise healthy eyes.
The procedure may not be done during pregnancy or breast-feeding. You also may not be eligible for the surgery if you have an uncontrolled autoimmune or connective tissue disease.
How Well It Works
PRK and LASEK effectively reduce mild to moderate nearsightedness.
Overall, the results of PRK are stable over the long-term. The results of PRK have improved as techniques and lasers have evolved and changed.1
PRK has been shown to be very effective in reducing mild to moderate nearsightedness. Almost everyone notices improvements in their vision. But not everyone gets perfect 20/20 vision. Results show that after surgery:2
- 67% to 98% of people have 20/40 vision or better.
- 48% to 86% have 20/20 vision or better.
PRK tends to have more stable results than RK, with less need for retreatment and less hyperopic shift, or increasing farsightedness, for 8 to 10 years after surgery. For instance, 58% to 95% of people have vision within 1 diopter of the intended surgical correction 1 year after surgery.2
In general, most people with mild or moderate nearsightedness can expect to have uncorrected vision of 20/40 or better (without glasses or contacts) after PRK surgery. Results in people who are more nearsighted are harder to predict.1
Photorefractive keratectomy has been used in the United States since 1988.
Risks
The risks associated with PRK and LASEK are similar.
The problem most commonly associated with PRK is clouded vision (sometimes also referred to as haze). Some eyes treated with PRK have some clouding of the cornea as a result of healing. This clouding usually reaches a peak about 4 months after surgery and then clears up by 1 year.1 At its peak, the clouding may reduce vision by 2 or more lines on the eye chart. Clouding appears to be more common in people who are very nearsighted. Clouding may be linked with spending a lot of time in the sun.
Some doctors recommend a medicine when you have surgery to lower the chance of haze. Some doctors may recommend avoiding direct sunlight for a while after your surgery, taking vitamin C, and wearing sunglasses.
Other complications of PRK may include:
- Night vision problems, such as halos (often described as a shimmering circle around light sources such as headlights or street lamps).
- Glare, or increased sensitivity to bright light.
- Double vision (diplopia), usually in one eye. Some people describe this as "ghosting" around an object, rather than a doubling.
- New astigmatism.
- Overcorrection or undercorrection.
- Regression. As the cornea heals, cells may fill in the area that was shaped by the laser, causing at least some of the nearsightedness to come back. Regression may also occur if the treated area thickens as part of the healing process. Regression may occur up to 2 years after surgery. Medicines are sometimes used to control and limit regression.
- Loss of best corrected vision, which is the best possible vision you can achieve using glasses or contact lenses. This is not common (happening about 3 times out of 100) but the risk rises with severe nearsightedness.1
Retreatment may be desired if you have residual nearsightedness that results from undercorrection or regression.
Serious but rare complications may include:
- Infection.
- Sores (ulcers) on the cornea.
- Elevated pressure inside the eye (intraocular pressure) and glaucoma.
PRK is considered safe. PRK has been approved by the U.S. Food and Drug Administration (FDA) since 1995. No deaths have been reported as a result of the operation, and serious complications are rare. But the procedure may have long-term side effects or complications that we do not yet know about.
What To Think About
If you are considering having surgery to improve nearsightedness, consider the different options (LASIK, PRK, LASEK, corneal ring implants, intraocular lens implants, and radial keratotomy), and discuss them with your doctor. PRK and LASIK surgery have replaced radial keratotomy as the refractive surgeries chosen by most people.
There is no agreement about whether PRK is superior to LASIK, or vice versa, for people with mild to moderate nearsightedness. But with high degrees of nearsightedness, LASIK is often done instead of PRK because of the risk of clouding (haze) with PRK.
PRK is a cosmetic procedure. The cost of refractive surgery varies in different locations, but it can be a significant expense. Most insurance companies do not cover the cost of refractive surgery.
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| Author: | Robin Parks, MS | Last Updated: July 7, 2007 |
| Medical Review: | Kathleen Romito, MD - Family Medicine Carol L. Karp, MD - Ophthalmology | |
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| Topic Contents | |
| Surgery Overview | |
| What To Expect After Surgery | |
| Why It Is Done | |
| How Well It Works | |
| Risks | |
| What To Think About | |
| References | |