When most people think of laser eye surgery, they usually think of LASIK. But there’s another refractive eye correction called Photorefractive Keratectomy (PRK). What’s the difference? It’s all about access and healing.
For both procedures, the eyes are prepared similarly with topical anesthetic drops. Next, we need to gain access to the relatively inert middle layer of the cornea, called the stroma, which is just under the cornea’s superficial skin. The stroma is like clear cartilage and does not grow back once sculpted. This makes the stroma the ideal place to sculpt the patient’s eyeglass prescription permanently.
Accessing the stroma with LASIK vs. PRK
So how do we access the stroma?
With LASIK surgery, the surgeon will utilize a femtosecond laser to make a very thin (100 micron) hinged flap on the surface of the cornea. This LASIK flap consists of the superficial skin of the cornea, in addition to a very small sliver of the corneal stroma. The flap will then be lifted to provide access to the corneal stroma, which is the part of the eye that is permanently sculpted to correct the vision. Once the sculpting treatment is complete, the flap is then replaced to allow a quick recovery.
During PRK surgery, after the eye is anesthetized, the top layer of corneal skin is gently brushed away in a controlled fashion to provide access to that same corneal stroma. The stroma is then sculpted using the EXACT same excimer laser that is utilized during LASIK to reshape the cornea and correct the vision. At the end of the procedure, a ‘bandage’ contact lens is placed in the eye to promote comfortable healing for approximately 5 days. This lens is essentially a clear contact lens with no prescription. The corneal skin that was removed will regenerate and repair itself over the next several weeks.
What about the recovery process?
With LASIK, the flap is simply placed back in position at the end of the procedure. Healing is very fast. Most patients feel light sensitive and mild discomfort for the first 5-6 hours after the procedure, but can quickly resume most normal activities. The vision is dramatically better within 10 hours after the surgery, and most patients feel very comfortable to drive by the next day. Patients typically continue their drops to prevent infection and minimize inflammation for one week.
With PRK, a bandage contact lens is placed over the eye to promote regeneration of the corneal skin layer as comfortably as possible. Despite this measure, many patients remain light sensitive and may have mild discomfort for 1-4 days. Pain medication is often prescribed by the surgeon to be used if needed during early recovery. As the corneal skin layer regenerates and heals, the vision is functional, but not crystal clear. Although full visual recover can take about a month, most patients can resume normal activities, including driving and going back to work, after the bandage contact lens is removed (typically about 5 days after the PRK surgery). Patients take antibiotic drops to prevent infection for the first week after PRK, but they typically continue with a tapering dose of anti-inflammatory drops for 1-3 months.
PRK may be an alternative to LASIK for patients with thin or irregularly shaped corneas, patients who have a very high refractive error, or patients who have already undergone a LASIK procedure.
Which should you have—LASIK or PRK?
The final visual outcome for both LASIK and PRK is the same. For most patients, LASIK is the clear choice because the recovery time is much quicker. Typically, patients can resume driving and going back to work the following day with less follow-up appointments and less medication.
But LASIK is not the best choice for everyone. The best choice is the safest choice, and that’s what your surgeon will determine at your consultation.
LASIK is not a safe option for patients with thin or irregularly shaped corneas, or for some patients who have a very high refractive error. There are also scenarios when a PRK enhancement is advised years after a patient has already undergone a LASIK procedure. The main drawback to PRK (compared to LASIK) is inconvenience, but the vision correction is equal. A discussion with your surgeon will help guide you toward the safest and best option.