Definition and Overview

Photoreactive keratectomy (PRK) is a noninvasive outpatient procedure that involves the use of laser technology to treat refractive errors such as astigmatism, nearsightedness (myopia), and farsightedness (hyperopia). It works by removing the epithelial cells of the cornea (the transparent layer in the front of the eyes) and reshaping corneal tissues.

The procedure is often compared with laser in-situ keratomileusis (LASIK) since both treatments are nonsurgical and are intended as refractive error treatments. However, they are different since LASIK leaves a flap rather than ablating the entire outermost layer of cells.

Who Should Undergo and Expected Results

PRK is generally an elective surgical procedure that can be taken advantage of by people who have:

  • Low to moderate refractive errors – The severity of the eye condition can be confirmed through different optical tests. PRK is recommended if the refractive errors are categorised as low or moderate. Otherwise, a cornea transplant or other surgical treatments may be recommended to the patient.
  • Thin corneas, since they are much easier to reshape without using an invasive approach
  • Contact lenses or prescription eyeglasses – One of the major reasons why people undergo the treatment is to get rid of these accessories. This also makes the procedure beneficial to those who drive regularly, are into sports, or those who want to gain better and greater mobility.

Although it is not recommended for people who have glaucoma, a degenerative eye problem characterised by the permanent damage to the optical nerves, the procedure can be performed on those who have already undergone a glaucoma surgery.

Meanwhile, PRK is not ideal for people who have underlying conditions such as diabetes, macular disease, and scarred corneas. Women who are currently pregnant or are breastfeeding are typically advised to delay the procedure until they have given birth or have weaned their baby.

The prognosis of PRK is good. In the majority of cases, patients no longer need glasses or contact lenses, or have significantly reduced their dependency on these accessories. Nevertheless, patients should be aware that PRK doesn’t have the capability to prevent any future eye conditions such as glaucoma, tumours, or even blindness.

How Does the Procedure Work?

Although PRK is a quick and straightforward procedure, it requires planning that includes performing eye evaluations and tests. One of the most important is cornea topography, which provides a visual representation of the cornea so the ophthalmologist can determine how the cornea should be reshaped to achieve the desired result. The eye doctor may also perform a physical exam, review the patient’s medical records, and discuss pre-operative instructions such as removing and not using any contact lenses at least three weeks before the procedure.

PRK doesn’t require general anaesthesia but the patient is typically sedated and an eye drop is used to numb the affected eye.

In the procedure, the patient lies relaxed on the operating table. A special microscope is then placed in front of the eyes to allow the doctor to see the cornea properly. An excimer laser is then used to ablate the outermost layer of the eye that is composed of epithelial cells. The surgeon then reshapes the rest of the corneal tissue depending on the refractive error and desired result.

The procedure takes at least an hour for each eye, after which a bandage is placed to allow the cells to heal and start regenerating. This bandage is removed during the first follow-up session, which is typically scheduled four days after the procedure.

Possible Risks and Complications

Compared to LASIK, PRK has lesser risks and complications, especially since there’s no flap tissue to deal with. However, discomfort, pain, and blurry vision may persist for as long as three months. Some patients also complain of dry eye, which can be either permanent or temporary, as well as the presence of halos or starbursts and permanent scarring on the cornea, which can make vision hazy.


References:

  • Kramarevsky N, Hardten DR. Excimer laser photorefractive keratectomy. In: Yanoff M, Duker JS, eds. Ophthalmology. 3rd ed. St. Louis, MO: Elsevier Mosby; 2008:chap 3.4.

  • Olitsky SE, Hug D, Plummer L, Stass-Isern M. Abnormalities of refraction and accommodation. In: Kliegman RM, Behrman RE, Jenson HB, Stanton BF, eds. Nelson Textbook of Pediatrics. 19th ed. Philadelphia, PA: Elsevier Saunders; 2011:chap 612.

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