Photorefractive Keratectomy

Photorefractive keratectomy (PRK) is a type of laser eye surgery that corrects common vision problems like nearsightedness, farsightedness, and astigmatism. A trained eye surgeon reshapes the cornea, the clear front part of your eye, using a laser. Unlike other procedures, PRK does not create a corneal flap, making it an option for some people with thinner corneas.

What is Photorefractive Keratectomy?

Photorefractive keratectomy (PRK) is a type of laser eye surgery that reshapes the cornea, the clear, dome-shaped front surface of your eye, to correct vision problems. It uses an excimer laser to precisely remove tiny amounts of tissue, helping light focus correctly on the retina. This procedure is an alternative to wearing glasses or contact lenses.

PRK is a common procedure performed by an eye surgeon (ophthalmologist). It aims to improve your vision by changing the curvature of your cornea. By altering the cornea's shape, the surgery helps light rays bend (refract) properly, allowing for clearer vision. One key difference between PRK and other laser eye surgeries, like LASIK, is how the surgeon accesses the cornea. In PRK, the surgeon gently removes the outer protective layer of the cornea, called the epithelium, before using the laser. This layer then naturally regrows over a few days after the procedure.

Why it's done

Photorefractive keratectomy (PRK) is performed to correct refractive errors, which are common vision problems that prevent light from focusing properly on the retina. These include nearsightedness (myopia), farsightedness (hyperopia), and astigmatism. It offers a way to reduce or eliminate the need for corrective lenses like glasses or contact lenses.

People choose PRK to improve their vision and gain more freedom from daily corrective eyewear. Nearsightedness (myopia) makes distant objects appear blurry, while farsightedness (hyperopia) causes close-up objects to be out of focus. Astigmatism results from an irregularly shaped cornea, leading to blurred or distorted vision at all distances. Your eye doctor may recommend PRK if you have stable vision, are at least 18 years old, and have healthy eyes. It might be a preferred option over other laser surgeries if you have thin corneas or participate in activities where a corneal flap (created in procedures like LASIK) could be dislodged, such as contact sports.

How to prepare

Preparing for photorefractive keratectomy (PRK) involves several important steps to ensure the best possible outcome and safety. You will undergo a comprehensive eye exam to determine if you are a suitable candidate and to measure your eyes precisely. Your doctor will also provide specific instructions, including when to stop wearing contact lenses.

Before your PRK procedure, your eye surgeon will conduct a thorough eye examination. This exam measures your vision, corneal thickness, pupil size, and checks for any underlying eye conditions that could affect the surgery. It's crucial to be honest about your medical history and any medications you are taking. You will need to stop wearing contact lenses for a specific period before your exam and surgery. Soft contact lenses usually need to be removed 1 to 2 weeks prior, while toric or hard contact lenses may require a longer period, as advised by your doctor. This allows your cornea to return to its natural shape. On the day of the surgery, avoid wearing eye makeup, lotions, or perfumes, and arrange for someone to drive you home, as your vision will be blurry.

What happens during

During photorefractive keratectomy (PRK), the procedure typically takes about 15 minutes per eye. Your surgeon will first numb your eyes with drops and use a device to keep your eyelids open. The outer layer of your cornea is then gently removed, and a specialized laser reshapes the underlying corneal tissue to correct your vision.

Once your eyes are numbed with anesthetic eye drops, your surgeon will position you under the excimer laser. A small instrument will be used to hold your eyelids open, preventing you from blinking during the procedure. The surgeon then carefully removes the thin, outer layer of your cornea (the epithelium). This can be done using an alcohol solution, a brush, or a blunt surgical instrument. After the epithelium is removed, the excimer laser is precisely guided to reshape the underlying corneal tissue. You will be asked to focus on a target light during this part of the procedure. The laser pulses are very quick and quiet. Once the reshaping is complete, a clear, soft bandage contact lens is placed on your eye to protect it while the epithelium heals. This bandage lens is not for vision correction and will be removed by your doctor a few days later.

Recovery & timeline

Recovery from photorefractive keratectomy (PRK) is a gradual process, with initial discomfort and blurry vision lasting a few days. The outer layer of your cornea will heal over the first 3 to 5 days, during which a bandage contact lens protects your eye. While vision improves steadily, it can take several weeks to months for your vision to fully stabilize and achieve its final clarity.

Immediately after PRK, you may experience some pain, discomfort, light sensitivity, and a gritty sensation in your eyes for the first 1 to 3 days. Your doctor will prescribe pain medication and eye drops to manage discomfort and prevent infection. It's important to use these drops as directed. Your vision will be blurry at first, similar to looking through a hazy window. The bandage contact lens is typically removed by your eye doctor after 3 to 5 days, once the new epithelial layer has grown back. Over the next few weeks and months, your vision will continue to improve. Many people notice significant improvement within the first month, but full visual clarity and stability can take 3 to 6 months. You will need to use various eye drops for several weeks or even months to aid healing and prevent complications like corneal haze. During recovery, avoid rubbing your eyes, swimming, hot tubs, and strenuous exercise for at least 1 to 2 weeks. Protecting your eyes from the sun with sunglasses is also recommended.

Risks & side effects

Like any surgical procedure, photorefractive keratectomy (PRK) carries potential risks and side effects, although serious complications are rare. Common temporary side effects include dry eyes, glare, halos, and starbursts, especially at night. Other less common risks can include infection, corneal haze, undercorrection or overcorrection, and, very rarely, permanent vision loss.

Many people experience some degree of dry eyes after PRK, which can last for several weeks or months. Your doctor may recommend lubricating eye drops to help manage this. You might also notice visual disturbances such as glare, halos (bright rings around lights), or starbursts (streaks of light radiating from sources) in low-light conditions, particularly at night. These usually improve over time as your eyes heal. Less common but more serious risks include infection, which can be minimized by using prescribed antibiotic eye drops. Some people may develop corneal haze, a clouding of the cornea, which can sometimes be treated with additional eye drops or further procedures. There's also a chance of undercorrection (not enough tissue removed, requiring glasses or another procedure) or overcorrection (too much tissue removed). While extremely rare, there is a risk of significant vision loss. It's important to discuss all potential risks with your surgeon before deciding on PRK.

Success rate

Photorefractive keratectomy (PRK) has a high success rate in improving vision and reducing dependence on glasses or contact lenses. Most people achieve 20/20 vision or better, or at least 20/40 vision, which is sufficient for driving without corrective lenses in most places. The effectiveness of PRK is well-documented for correcting various refractive errors.

Studies show that PRK is a very effective procedure for correcting nearsightedness, farsightedness, and astigmatism. A large majority of people who undergo PRK achieve excellent visual outcomes. For example, many achieve 20/20 vision, meaning they can see at 20 feet what a person with normal vision can see at 20 feet. Even if 20/20 vision isn't achieved, most people reach 20/40 vision or better, which significantly improves their quality of life and often allows them to pass driving tests without corrective lenses. The long-term outcomes of PRK are generally stable. While some people may experience a slight regression (return of some refractive error) over time, this is usually minor and can often be managed with glasses, contact lenses, or, in some cases, an enhancement procedure. Your surgeon will discuss realistic expectations for your specific vision correction goals based on your eye health and prescription.

Frequently asked questions

Is PRK painful?

During the PRK procedure, your eyes are numbed with anesthetic drops, so you should not feel pain. After the surgery, it is common to experience some pain, discomfort, and a gritty sensation for the first 1 to 3 days as your cornea heals. Your doctor will prescribe medication to help manage this discomfort.

How long does PRK surgery take?

The actual laser treatment part of photorefractive keratectomy (PRK) is very quick, usually lasting less than a minute per eye. The entire procedure, including preparation and the surgeon's work, typically takes about 15 minutes for each eye.

How soon can I see clearly after PRK?

Your vision will be blurry immediately after PRK and will gradually improve over several days to weeks. While some improvement is noticeable within the first week, it can take 3 to 6 months for your vision to fully stabilize and reach its final clarity.

Can I get PRK if I have thin corneas?

Yes, PRK is often a suitable option for people with thinner corneas who may not be candidates for other laser eye surgeries like LASIK. This is because PRK does not involve creating a corneal flap, which preserves more corneal tissue. Your eye surgeon will assess your corneal thickness during your pre-operative exam.

Will I still need glasses after PRK?

The goal of PRK is to reduce or eliminate your need for glasses or contact lenses. Most people achieve excellent vision and no longer require corrective eyewear for most activities. However, some individuals may still need glasses for certain tasks, like reading, especially as they age, or for fine-tuning vision.

How long do I need to use eye drops after PRK?

You will need to use various eye drops for several weeks to months after PRK. These typically include antibiotic drops to prevent infection, anti-inflammatory drops to aid healing and reduce haze, and lubricating drops for dry eyes. Your doctor will provide a specific schedule for your eye drop regimen.

Sources

• MedlinePlus — Photorefractive Keratectomy
• Mayo Clinic — Photorefractive Keratectomy
• Cochrane Library — Photorefractive Keratectomy