PRK: Laser Vision Correction Without a Flap

How PRK works

The cornea's outer layer, the epithelium, is a thin skin about 50 microns thick that regenerates constantly. In PRK the surgeon removes the epithelium from the central cornea, with a dilute alcohol solution or a soft brush, and applies the excimer laser directly to the tissue beneath. The laser removes tissue in the pattern your measurements prescribed, in 10 to 60 seconds per eye, correcting nearsightedness, farsightedness or astigmatism. A soft bandage contact lens is then placed, and the epithelium regrows underneath it over the following days.

The reshaping is identical to LASIK. What differs is the way the laser reaches the cornea: LASIK lifts a flap of tissue and treats beneath it; PRK treats the surface and lets the surface heal.

Why choose PRK over LASIK

PRK is recommended, rather than merely offered, in several situations:

• Corneas too thin for a LASIK flap plus treatment to leave a safe margin
• Mild surface irregularity or scarring, where a flap would be unpredictable
• Patients in contact sports, law enforcement or the military, where a flap could be displaced by a blow
• Some patients with dry eye concerns; dry eye is usually temporary after either procedure, and your surgeon reviews your risk
• Enhancement after previous LASIK when the flap is not suitable for lifting

For eyes that are equally suited to both, the choice usually comes down to recovery time, and most of those patients choose LASIK.

What recovery is really like

The honest difference between PRK and LASIK is the first week. While the epithelium regrows, the eye is sore, watery and light sensitive; days two and three are usually the most uncomfortable, and most patients take the week off work. The bandage lens comes out at day four or five once the surface has closed, and comfort improves quickly. Vision is usable but hazy for the first weeks, meets the driving standard for most patients within one to two weeks, and sharpens over one to three months to the same end point LASIK reaches. Sun protection is important for the first year because the healing surface is prone to haze, and a course of drops guards against it.

Results and safety

Long term studies show PRK and LASIK reach equivalent visual outcomes. PRK has no flap, so flap complications cannot occur, and it leaves more corneal tissue for a given prescription. Its risks are a slower, more uncomfortable healing period, a small chance of corneal haze that is managed with drops and sun protection, and, as with all laser correction, dryness that improves over months. PRK does not treat prescriptions beyond the corneal range any more than LASIK does; for those, the EVO ICL is the answer.