The goal of laser vision correction (LVC) is to eliminate or reduce the need for glasses and contact lenses. LVC treats three basic refractive errors: myopia (nearsightedness), astigmatism (blurring of vision due to non-spherical shape of the eye), and hyperopia (farsightedness).
During an LVC procedure, the cornea — the clear dome on the surface of the eye — is reshaped in order to correct the refractive error. The different techniques to perform LVC are laser in situ keratomileusis (LASIK), phototherapeutic refractive keratectomy (PRK), and small incision lenticule extraction (SMILE).
LASIK and PRK
LASIK, the most commonly performed laser vision correction procedure in the US and the most famous of the techniques, was approved by the FDA in 1998. It is well known for its quick recovery. LASIK combines the application of excimer laser and a hinged corneal flap. The excimer laser is a computer-controlled laser that allows precise control over the amounts of tissue that are removed from the cornea. The corneal flap is a layer of the cornea that is folded back to provide access to a deeper layer of the cornea that is reshaped by the excimer laser during the procedure.
LASIK has a much quicker and more comfortable recovery compared to PRK. After LASIK, patients typically experience a scratching and burning sensation that significantly improves within one day. Most patients have excellent vision the day after LASIK. In the first week especially, patients need to be mindful of the corneal flap, which has a small chance of moving or dislocating with rubbing or hard blinking. Even months after the procedure, there is a small risk of flap dislocation with significant trauma.
The most common side effect or risk of LVC is dry eye. Typically, the dryness goes away within a week or two, but in other cases it can require ongoing treatment. The refractive surgeon should screen for dry eye at the preoperative consultation, and treat it prior to the procedure to reduce risk of chronic issues afterward. LASIK is thought to have a slightly higher risk of dry eye compared to SMILE and PRK.
PRK was approved by the FDA in 1995 and was the first type of LVC performed. During PRK, the outer layer of corneal skin cells is removed, followed by the use of the excimer laser to reshape the corneal tissue to correct vision. Patients typically experience 48 to 72 hours of scratching, tearing, burning, and light sensitivity after PRK, often requiring short-term pain medication. Most patients have functional vision during this time, and are able to drive and resume most activities by the fourth or fifth day after the procedure. The PRK recovery is longer and less comfortable than recovery after LASIK and SMILE. The main benefits of PRK are no flap and reduced risk of dry eye. PRK is an excellent option for patients with