Photorefractive Keratectomy (PRK)

PRK is a type of refractive surgery. This type of surgery uses a laser to treat vision problems caused by refractive errors. You have a refractive error when your eye doesn't focus light properly.

To see clearly, light rays must travel through your cornea and lens. The cornea and lens refract light so that it focuses on the retina. The retina converts light into signals that are sent to your brain and become images. When you have refractive errors (nearsightedness, farsightedness, astigmatism), the shape of your cornea or lens prevents light from focusing properly. When light is not focused on the retina as it should, your vision is blurred.

With PRK, your eye doctor uses a laser to change the shape of your cornea. This improves the way light is focused on the retina. PRK is used to treat nearsightedness (myopia), farsightedness (hyperopia), and astigmatism.

The goal of PRK is to correct your refractive error to improve your vision. 

Who is a good candidate for PRK?

If you have dry eyes or a thin cornea and want to undergo refractive surgery, PRK may be a good option for you. This is because some other types of refractive surgery, such as LASIK, may not be suitable in such cases.

Also, if you have a very active lifestyle or work, PRK may be a better option for you than LASIK or similar procedures. This is because PRK does not involve creating a flap in the cornea like LASIK and similar surgeries. In the event of an injury, the corneal flap could become displaced, causing problems.

To undergo PRK surgery, certain conditions must be met. Some of them are:

You must be 18 years of age or older (ideally, over 21 years of age, when your vision is most likely to have stopped changing).

Your eyeglass prescription shouldn't have changed much in the last year.

You need to have realistic expectations about what PRK can and cannot do for you.

Some people are not good candidates for PRK. They include people with:

• an unstable (changing) refractive error
• extreme levels of myopia, hyperopia, or astigmatism
• thin corneas
• corneal erosions or diseases
• advanced glaucom
• cataracts affecting vision
• certain eye infections
• uncontrolled diabetes
• pregnancy

A detailed examination and preoperative screening will show whether you are suitable for PRK surgery.

What to expect with PRK?

Before surgery

You and your eye doctor will discuss your vision needs based on your lifestyle. For example, if you are involved in sports, are a professional driver…

The ophthalmologist will carefully examine your eyes to determine if you are a good candidate for PRK. The procedure includes:

Your vision test. This is done to confirm that your vision has not changed. It also shows how high your refractive error is and whether PRK can be used to correct your vision.

Checking for other eye problems. The eye doctor will make sure that you do not have any eye problems. This is because other problems could affect your surgery or its prognosis. For example, if you have dry eyes, it may become worse after PRK.

Measuring and mapping your corneal surface. The ophthalmologist will check the thickness of your cornea and take precise measurements of the corneal surface. The surgeon uses these measurements to program the laser used during surgery.

Measurement of the pupil size of the eye. If the pupil is too large, you may notice ghosting at night after PRK.

During PRK

Your eye will be anesthetized with eye drops.

Your surgeon will place an eyelid dilator in your eye to keep you from blinking. Your eye doctor will then remove the outer layer of cells of your cornea, called the epithelium. To do this, he or she may use a laser or an alcohol solution.

You will be asked to look at a bright target without moving your eyes. The surgeon will use a laser to change the curvature of the cornea. 

After PRK

Immediately after surgery, your eye doctor will place a contact lens over your eye to help it heal.

You should return home and sleep or simply relax after the surgery.

Your surgeon may suggest that you take a few days off work. You should also avoid strenuous activity for a week after surgery, as this could slow down the healing process.

For two to three days after PRK, you may have some eye pain. You will be given eye drops and instructions for this. You will need to use eye drops for up to 3 months or as prescribed by your eye doctor. Be sure to follow your doctor's instructions for using them to help with healing.

After PRK, you will need to wear sunglasses outside for as long as your doctor advises. This is because sun exposure can lead to corneal scarring after surgery, causing vision problems.

Initially, your vision will be blurry after PRK. Over 3-5 days, your vision will gradually improve. Keep in mind that it may take a month or more to achieve optimal vision.

What are the risks with PRK?

Like any surgery, PRK carries risks of problems or complications that you should consider. Most are temporary and resolve within the first few days 

These can include:

eye pain or discomfort, blurred vision, light sensitivity, redness of the white of the eye

Other rare risks include:

eye infection, worse vision than before PRK, even with glasses or contact lenses 

Also, in a very small percentage, the refractive error may be over- or undercorrected, in which case additional laser surgery may be required.