PRK (or photorefractive keratectomy) is a laser eye surgery that is very similar to LASIK. The primary difference between the two is that in PRK, no flap is created on the cornea prior to reshaping the eye with an excimer laser.
Though you may not be familiar with PRK, it has been around longer than LASIK and once was the most common laser vision correction procedure.
Like LASIK, PRK can correct a wide range of nearsightedness, farsightedness and astigmatism, and many studies indicate PRK provides virtually the same long-term visual outcomes and success rates as LASIK.
Advantages of PRK
The primary advantage of PRK over LASIK is that there is no risk of flap problems during or after PRK surgery. This is a particularly important consideration for people whose profession or lifestyle puts them at risk for eye injuries. (Examples include: military personnel, policemen and professional or amateur boxers.)
Another advantage of PRK is that the laser reshaping of the eye takes place closer to the surface of the cornea than in LASIK. Therefore, PRK sometimes can be safely performed on eyes with corneas that may be too thin for LASIK eye surgery.
Disadvantages of PRK
Vision recovery takes longer after PRK than after LASIK, and there is more discomfort during the first few days after surgery.
In some cases, people who have PRK cannot see well enough to drive safely or perform their normal workday tasks for several days after surgery.
Also, until a new layer of surface cells (called epithelial cells) grows back over the laser-treated portion of the cornea, PRK patients may have a greater risk of eye infections than LASIK patients during the first few days after surgery.
There is also a greater risk of mild or moderate haziness developing in the cornea from PRK surgery. This corneal haze may last a few months or it may be permanent, and it may or may not noticeably affect vision.
In some cases, it may take three to six months to achieve optimum vision after PRK.
Before PRK Surgery
If you are considering PRK, your first step is to choose a refractive surgeon and schedule a pre-operative exam and consultation. During this visit, your PRK surgeon or another eye doctor will examine your eyes to determine if you are a good candidate for laser vision correction.
Be sure to mention any medical conditions you have and any history of previous eye surgery or injuries. Some conditions may disqualify you altogether as a PRK candidate; others may mean a postponement of the procedure or a need for special care afterward.
During PRK Surgery
PRK is an ambulatory procedure – you walk into the surgery center, have the procedure, and walk out again. The entire surgery usually takes less than 15 minutes and you are awake the whole time.
The basic steps of PRK surgery are:
- Your eye is anesthetized with special numbing eye drops.
- A retainer is placed under your eyelids to keep your eye open throughout the procedure.
- After the surface of your eye is completely numb, the surgeon removes the thin outer layer of the cornea (called the epithelium).
- After the epithelium is removed, the excimer laser is positioned directly over your eye.
- You will be asked to look at a small light within the housing of the laser for a short time while your surgeon watches your eye through an operating microscope.
- The laser is activated and begins reshaping your cornea. It will make a loud clicking sound during the procedure, and you may smell a faint odor.
- After the laser treatment is finished, medicated eye drops and a bandage contact lens will be applied to your eye.
The actual laser treatment during PRK usually takes less than a minute. If you have only a mild eyeglasses prescription prior to surgery, it may take only a few seconds.
If you are having both eyes done the same day, the surgeon generally will proceed immediately to the second eye once the laser treatment of the first eye is finished. If you prefer, you have the option of having PRK surgery performed on your other eye a week or two later, after the vision in your first eye has recovered.
After PRK Surgery
After PRK, your eye surgeon will instruct you to use medicated eye drops several times a day for a period of time to reduce the risk of infection and inflammation. You may also be given a prescription pain reliever to control discomfort the first few days after surgery.
As with any kind of eye surgery, it’s important that you follow your surgeon’s instructions to the letter after PRK. Get proper rest, use your medications as directed, and call your eye doctor immediately if you suspect a problem.
Most people achieve 20/20 or better vision after PRK, but results vary from person to person. It’s possible you may still need to wear eyeglasses after PRK for specific tasks such as reading and driving at night. In some cases, a second PRK surgery (called an enhancement) may be required for you to achieve acceptable visual acuity without glasses or contact lenses.
PRK Risks and Complications
The risks and potential complications of PRK are similar to those associated with LASIK, and include:
- Dry eyes
- Vision problems, such as poor night vision, glare, halos and haze
- Incomplete or inaccurate vision correction
- Infection or inflammation following surgery
Corneal haze may also occur after PRK, reducing the sharpness of vision. In many cases, corneal haze detected shortly after surgery diminishes over time and disappears after six months.
Your eye doctor or refractive surgeon can give you more information about the risks and potential complications of PRK as they apply to your specific situation.