In patients with high degrees of myopia, a hyperopic shift can be of concern for several months to years postoperatively. With ALK, postoperative uncorrected vision is much better than preoperative uncorrected vision, but maximum visual improvement may not be obtained for weeks to months after surgery. Pain or discomfort is minimal. Because of ALK's increased incidence of the need for enhancement, RK, AK, or PRK may be required. Glare may occur without the star-burst effect.
Regression is also a possibility.
Because it involves the creation of a corneal flap, ALK requires greater surgical expertise than procedures that do not, and irregular astigmatism can be a problem after surgery. During this period, vision is not good and pain or discomfort can be considerable. Maximum vision benefit is not obtained until 3 to 6 months after surgery. Corneal haze can develop and interfere with vision. PRK re-treatment or RK enhancement may be needed to deal with regression or undercorrection.