Photorefractive Keratectomy (PRK) is a type of laser eye surgery designed to correct common vision problems, known as refractive errors. This procedure is a form of surface ablation, meaning it works on the outermost layers of the eye to permanently change its focusing power. The primary goal of PRK is to reshape the cornea, the clear, dome-shaped front surface of the eye, to improve how light is focused onto the retina. By modifying the corneal curvature, the surgery effectively treats conditions like nearsightedness (myopia), farsightedness (hyperopia), and astigmatism, aiming to reduce or eliminate the need for glasses or contact lenses.
How the PRK Procedure Works
The PRK procedure begins after the eye is numbed using topical anesthetic drops. The surgeon then uses an instrument to gently hold the eyelids open, preventing blinking throughout the operation. Unlike other laser procedures that involve creating a corneal flap, PRK requires the removal of the cornea’s entire outermost layer, called the epithelium, to access the underlying tissue for treatment.
This epithelial removal is often performed using a dilute alcohol solution, a specialized brush, or a technique called transepithelial ablation where the laser removes the layer directly. Once the underlying corneal tissue, the stroma, is exposed, a computer-guided excimer laser is employed to precisely remove microscopic amounts of tissue. The laser is programmed with the patient’s unique measurements to correct the refractive error by sculpting the corneal surface.
For nearsightedness, the laser flattens the central cornea, reducing its refractive power so light focuses correctly on the retina. Conversely, for farsightedness, the laser is used to steepen the central cornea by removing tissue in a ring-like pattern around the periphery. The entire laser application process typically takes less than a minute per eye. A soft, clear bandage contact lens is immediately placed over the treated area to protect the exposed stroma and facilitate the healing of the epithelial layer.
The Healing Process and Visual Stabilization
The immediate post-operative period is characterized by a few days of discomfort, including a gritty sensation, excessive tearing, and light sensitivity. This sensation is a direct result of the large superficial abrasion created by the epithelial removal, which leaves the corneal nerves temporarily exposed. Patients are instructed to rest and use prescribed pain medication to manage symptoms during the initial 3 to 5 days.
The protective bandage contact lens remains in place for approximately five to seven days, serving as a shield while the epithelial cells regenerate and migrate to cover the treated area. Once the surface is fully healed, the surgeon removes the lens during a follow-up appointment, marking the end of the most uncomfortable phase of recovery. Vision is often still hazy and fluctuating because the new epithelial layer is not yet perfectly smooth.
Visual acuity improves gradually over weeks and months, a much slower process than with flap-based procedures. Patients commonly experience visual fluctuations during the second and third weeks post-surgery as the cornea continues to heal and stabilize. Significant visual clarity is often achieved around the one-month mark, though final, sharpest vision can take anywhere from three to six months to fully materialize.
A strict regimen of prescription eye drops is a part of the healing process to promote optimal outcomes. This regimen includes antibiotic drops to prevent infection and anti-inflammatory or steroid drops. These drops are important for several weeks to months to modulate the healing response and minimize the risk of developing corneal haze. Following the schedule for these drops and attending all follow-up appointments ensures the long-term success and stability of the vision correction.
Determining Suitability for PRK
PRK is often recommended as the preferred laser vision correction option for a specific subset of patients for whom other procedures, like LASIK, carry a higher risk of complication. The primary reason for choosing PRK is that it does not involve the creation of a permanent corneal flap. This structural difference makes PRK an excellent choice for individuals who have corneas that are naturally too thin to safely accommodate the tissue removed for a LASIK flap.
By avoiding the flap, PRK preserves more of the cornea’s biomechanical strength, which reduces the potential for a serious complication called ectasia, a progressive thinning and bulging of the cornea. This structural integrity also makes PRK the standard for individuals with active occupations or lifestyles, such as military personnel or those who participate in contact sports. In these scenarios, the absence of a flap eliminates the risk of traumatic flap displacement or injury that could occur from a direct blow to the eye.
The procedure is also a strong alternative for people with pre-existing conditions that affect the corneal surface, such as epithelial dystrophy or a history of dry eye syndrome. Since PRK works on the surface, it does not exacerbate dry eye symptoms to the same extent as procedures that involve deeper corneal incisions. A candidacy examination will confirm the exact thickness of the cornea and assess any other risk factors, ensuring that PRK is the safest and most effective method for achieving lasting vision correction.