LASIK and PRK are two of the most popular forms of laser vision correction. Both are designed to correct the patient’s nearsightedness and astigmatism by reshaping the patient’s cornea using an excimer laser. In LASIK, a corneal flap is first created and lifted, after which the underlying tissue is reshaped with the laser and then the flap is repositioned in place. In PRK, the cornea’s thin outer skin, called the epithelium, is first removed, and then the laser reshapes the underlying tissue. The epithelium layer subsequently regrows over the corneal surface, completing the healing process and preserving the new vision.
PRK is recommended when certain anatomical features of the patient’s eyes put the patient at risk for complications that are unique to LASIK. The two most common such features are thin corneas and structurally weak corneas, which are both genetic in nature. The creation of a LASIK flap on such eyes would put the corneas at risk for future deterioration of their strength and shape, a condition that could lead to permanent vision loss. PRK has been shown to be a safer alternative for patients with these corneal features.
The final visual results for PRK and LASIK are essentially the same. However, PRK does have a longer post-op recovery time. Because the epithelium layer must regrow over the surface of the cornea following PRK, patients experience up to 72 hours of varying degrees of discomfort, including stinging, scratchiness, light sensitivity, and tearing. Patients normally remain at home during this time and use prescribed medications to help minimize these symptoms.
The PRK procedure takes about five minutes per eye. While lying on your back, your eyes are numbed with special eye drops, after which one eye will be held open with a small eyelid holder. This eye will then be gently held in position for about 30 seconds during which you will feel a light pressure sensation on the eye. Following this, the laser will treat your eye for approximately 5 to 10 seconds as you stare at a blinking fixation light. You will not see or feel the laser. A thin, non-prescription contact lens is then placed on your eye over the treated area, which you’ll wear continuously until it’s removed about a week later.
You don’t have to worry about blinking because your eyelids will be held securely open with the eyelid holder. Also, because your eye is numb, you won’t typically feel the need to blink. Most advanced PRK laser systems are designed to automatically compensate for any involuntary or inadvertent movements of your eye or body during treatment.
Patients typically experience little, if any, discomfort during treatment.
Immediately following your PRK procedure, someone will need to drive you home. Plan on resting there for the next three days. You’ll need to wear protective goggles when you sleep during at least the first seven nights, and also to apply prescription eye drops throughout the day for the first month. You can use your eyes for any task, including use of computer displays, but expect your vision to be fairly blurry at all distances for the next few weeks, keeping in mind that your old glasses will no longer be useful at this point. While you can resume showering the day after your procedure, do not swim in a pool for at least two weeks or in the ocean or a lake for at least four weeks following your PRK treatment.
As long as your prescription is stable, you can expect your visual outcome to last for many years. If your vision does decline, however, the change is likely to be relatively small compared to your original prescription, and it’s something we can most likely address with an enhancement procedure.
Experiencing glare around lights at nighttime — including starbursts, ghosting and halos — is fairly common early in the PRK recovery process, and may make night driving difficult during the first few weeks. The effects should gradually lessen and, in the majority of patients, fully resolve within three to six months following surgery. A small percentage of patients, however, will continue to experience some degree of night disturbance indefinitely, but the effects are typically mild.