PRK (Photorefractive Keratectomy)

Evidence Based
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What is PRK (Photorefractive Keratectomy)?

PRK is a type of laser surgery that corrects refractive errors. If you have nearsightedness (myopia), farsightedness (hyperopia), astigmatism, or presbyopia (age-related farsightedness), you have a refractive error. 

These errors occur when your eye cannot focus light properly onto the retina (light-sensitive tissue of the eye). As a result, you have blurry vision. PRK can improve your vision safely and effectively to reduce dependence on corrective lenses.


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Pros and Cons of PRK Laser Eye Surgery 

Consider the benefits and drawbacks of PRK before proceeding. Some benefits of PRK include:

  • No corneal flap. LASIK (laser-assisted in situ keratomileusis), another form of laser refractive surgery, requires creating a flap on the cornea (clear tissue covering the front of the eye). This poses a risk of flap complications during and after surgery. For example, diffuse lamellar keratitis is an inflammation that can occur underneath the flap.
  • Better for high-impact activities. Since there is no corneal flap in PRK, there is no risk of the flap dislodging during sports or other activities that can result in eye trauma.
  • Less dry eye. The creation of a flap also affects the cornea's nerves, which can lead to increased dry eye. If you suffer from dry eye symptoms, your surgeon may recommend PRK over LASIK.
  • Safer for thinner corneas and high prescriptions. Since there is no flap, PRK requires less corneal tissue than LASIK. Thin corneas increase your risk of corneal ectasia (abnormal thinning) after surgery. High prescriptions require the removal of more corneal tissue.

Studies show that over 90% of people who receive PRK maintain excellent vision of 20/30 or better. These results are similar to those of LASIK. Some of these studies included patients who received PRK 13 to 19 years prior, which is indicative of the lasting benefits of PRK.

Some drawbacks of PRK include:

  • Longer recovery time. The advantage of the corneal flap in LASIK is that it allows for a quick recovery. In PRK, you must wait for the epithelium (outer layer of the cornea) to heal. It can take 1 to 3 months before your vision stabilizes.
  • More initial discomfort. Because the epithelium is open after PRK, you experience more discomfort after surgery. 
  • Less predictable outcomes. Although most people end up with excellent vision after PRK, your results depend on how your eyes heal. Some surgeons feel that LASIK provides more predictable outcomes.

Risks of PRK Vision Correction

Other drawbacks of PRK include potential risks and side effects. Although PRK is considered a safe procedure, no surgery is without its risks. Some considerations include:

  • Higher risk of infection. PRK essentially leaves your eye with an open wound while you wait for the epithelium to grow back. This leaves your eye more vulnerable to bacteria, which is why you must use antibiotic eye drops as directed by your surgeon.
  • Corneal haze. This type of scarring can develop if your eye does not heal properly. In most cases, this side effect goes away within a few months. In a small percentage of people, the haze affects vision permanently.
  • Halos or glare. As your eye heals, you may experience temporary halos and glare, especially at night. For most people, these side effects subside after a few months.
  • Dry eye. Any eye surgery that alters the corneal surface can potentially result in dry eye. However, these symptoms typically improve a few months after surgery.
  • Overcorrection or undercorrection. If your vision is over- or undercorrected, your surgeon may need to perform a touch-up PRK procedure or prescribe eyeglasses.

PRK Procedure (Step-by-Step)

PRK is a rapid procedure that lasts about 15 to 20 minutes for both eyes. Here’s what to expect:

  1. Before surgery, your ophthalmologist checks your eye health, pupil size, and refractive error. They take several measurements of your cornea to provide the laser with a map to guide your treatment. 
  2. On surgery day, you may receive anti-anxiety medication to relax you. You also receive numbing eye drops so that you do not feel pain during surgery.
  3. The surgeon places a speculum to hold your eyelids open during PRK.
  4. Before applying the laser, the surgeon uses an alcohol solution, laser, or surgical tools to remove the epithelium (outer) layer of your cornea.
  5. Then, an excimer laser removes and reshapes the corneal tissue underneath.
  6. Once the laser is finished, the surgeon places clear, bandage contact lenses to protect your corneas.
diagram showing four steps in photorefractive keratectomy (PRK) surgery

Is PRK Surgery Painful?

No, PRK is not painful since you receive numbing eye drops. However, you will experience some discomfort after surgery once the drops wear off. 

What Should I Expect After PRK?

Here are some things to expect after surgery:

  • On the day of surgery, you will need to arrange a ride home. 
  • Light sensitivity is common. The surgeon’s office usually provides you with dark shades to wear after surgery.
  • Do not plan to do any work or look at a computer screen that day. Just relax or take a nap.
  • Expect to take several days off work while you recover. After a few days, you can start driving if you feel comfortable, and your vision has cleared up. After a few weeks, you should be able to resume most daily activities.
  • Remember to use the medicated eye drops as directed. These include antibiotic drops to prevent infection and steroid drops to reduce inflammation. A standard course of eye drops lasts about a month.
  • If you have significant discomfort, your surgeon can recommend pain medications to take.
  • Do not skip follow-up appointments. Your surgeon needs to make sure your eyes are healing properly and address any complications that might arise. If your pain worsens or your vision gets more blurry, consult your surgeon right away.

Is PRK Permanent? 

Yes, the effects of PRK are permanent. However, your vision can change after surgery for other reasons, such as age-related cataracts. These changes are known as regression.

Is PRK Better Than LASIK?

Not necessarily. Studies show that both surgeries deliver similar outcomes. Although LASIK is more popular than PRK, not everyone is a good candidate for LASIK. Your surgeon needs to assess your vision, eye health, overall health, and expectations to determine which procedure is best.

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Author: Melody Huang, O.D. | UPDATED October 28, 2020
Resources

Guerin, Marc B., et al. “Excimer Laser Photorefractive Keratectomy for Low to Moderate Myopia Using a 5.0 Mm Treatment Zone and No Transitional Zone: 16-Year Follow-Up.” Journal of Cataract & Refractive Surgery, vol. 38, no. 7, 2012, pp. 1246–1250., doi:10.1016/j.jcrs.2012.03.027

Herz, Natasha H, and Brad H Feldman. “Photorefractive Keratectomy.” EyeWiki, 22 Jan. 2020, eyewiki.aao.org/Photorefractive_Keratectomy

Lake, Damian B. “Customized Ablations for Better Visual Outcomes.” CRSTEurope, crstodayeurope.com/articles/2011-jul/feature-story-customized-ablations-for-better-visual-outcomes.

Vestergaard, Anders H., et al. “Long-Term Outcomes of Photorefractive Keratectomy for Low to High Myopia: 13 to 19 Years of Follow-Up.” Journal of Refractive Surgery, vol. 29, no. 5, 2013, pp. 312–319., doi:10.3928/1081597x-20130415-02

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