Corneal refractive surgery
Author: Prof. Eric E. Gabison — ophthalmology, cornea & ocular surface. Updated 2026.
The corneal refractive landscape
Corneal refractive surgery changes the eye's power by reshaping the curvature of the cornea. The techniques share this optical goal and differ in how the stroma is reached and how much tissue is consumed.
Two great families divide the field. The first removes tissue by excimer photoablation, sculpting the stroma directly according to a calculated profile: this is the principle of surface photoablation (PRK) and LASIK, which then differ only in how the stroma is accessed. The second does not photoablate: it cuts and extracts a lenticule of intact stroma using the femtosecond laser alone, without excimer — the logic of SMILE and, more recently, SILK.
Within the photoablative family, the decisive dividing line opposes surface techniques (ablation after epithelial removal) to lamellar techniques (ablation under a stromal flap). This distinction governs pain, recovery speed, postoperative dryness and — crucially — the amount of load-bearing tissue preserved, hence the risk of ectasia. This whole course is organised around that trade-off between immediate comfort and biomechanical integrity.
Three ways to reach the same optical profile, three relationships to tissue: surface preserves load-bearing tissue but exposes the surface (pain, haze); LASIK offers comfort but consumes a flap; lenticule extraction avoids the flap and cuts fewer nerves — a theoretical advantage whose clinical superiority over LASIK is not established. The right operation is not "the newest technique" but the one that corrects without weakening, chosen on the patient's cornea.