Dry eye is the most common complication of LASIK. Corneal nerves that are responsible for tear production are severed when the flap is cut. Medical studies have shown that these nerves never return to normal densities and patterns. Symptoms of dry eye include pain, burning, foreign body sensation, scratchiness, soreness and eyelid sticking to the eyeball. The FDA website warns that LASIK-induced dry eye may be permanent. Approximately 20% of patients in FDA clinical trials experienced “worse” or “significantly worse” dry eyes at six months after LASIK.(1)
Behind the cornea is the colored part of the eye called the iris. The iris muscle controls the size of the pupil, regulating the amount of light entering the eye. In dim light the pupil opens to gather more light. The dark-adapted pupil diameter varies widely among individuals. In 2004, researchers found the pupil size of patients seeking refractive surgery ranged from 4.3 to 8.9 millimeters with an average of 6.5 millimeters.
Surface ablation such as PRK and LASEK are associated with risk of visually significant haze formation. Enhancement of previous LASIK with PRK (PRK on top of a LASIK flap) carries an increased risk of haze. This has led many surgeons to incorporate prophylactic use of Mitomycin C (MMC) during surface ablation to prevent haze.
After LASIK, the flap never recovers normal tensile strength. LASIK flaps may be accidentally dislodged or surgically re-lifted indefinitely. In 2005, researchers at Emory Eye Center, Emory University School of Medicine published their study of human eye bank corneas, which demonstrates the strength of the post-LASIK cornea at the flap interface is only 2% of normal corneal tensile strength.(1)
Intraocular pressure inside the eye pushes constantly against the back surface of the cornea. In a healthy eye, the collagen bands of the cornea provide support to withstand these forces. LASIK surgery involves cutting a corneal flap, which severs collagen bands that never reconnect. After creation of the flap, the surgeon uses a laser to remove corneal tissue, further thinning the cornea. Together, flap creation and laser ablation reduce stress-bearing thickness of the cornea, leaving the cornea permanently weakened.
Dry eye is the most common complication of LASIK. (1) FDA clinical trials demonstrate 20% of LASIK patient experience worse or significantly worse dry eyes six months after LASIK. (2) Symptoms of post-LASIK dry eye include pain, burning, stinging, and scratchiness. Dry eye after LASIK is due to surgically-induced disruption of processes involved in maintaining a healthy, normal tear film.