Introduction Definition and Terminology Laser subepithelial keratomileusis (LASEK) combines certain elements of both laser in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK). In LASEK—instead of completely removing the epithelium, as…

Introduction As refractive surgery has evolved from the controversial to the routine, more patients want to decrease their dependence on glasses. Laser in situ keratomileusis (LASIK) is a very common…

Introduction Decentration of the ablation and other factors have contributed to inducing irregular astigmatism in a certain number of eyes treated with laser refractive surgery. Topography-guided ablations present a surgical…

Introduction In the last 2 decades, the clinician’s ability to diagnose keratoconus has increased. This is due to the knowledge and development of diagnostic instruments for keratoconus, from corneal topography…

Introduction Anterior segment optical coherence tomography (OCT) has been incorporated into clinical practice in refractive surgery to customize preoperative selection and to improve postoperative evaluation and follow-up. Instruments The first…

Introduction The possibility of using the excimer laser for the cornea was first raised in the early 1980s. Using Munnerlyn’s equation, which established a relationship between the change in refractive…

Introduction Unlike methods of surface photoablation, the laser in situ keratomileusis (LASIK) technique requires a superficial corneal flap to be created prior to photoablation with an excimer laser. Mechanical microkeratomes…

Introduction Corneal topography provides an assessment of the anterior corneal surface shape, and corneal tomography includes an assessment of the posterior corneal surface shape, pachymetry, as well as biometry of…

Introduction Clinicians are accustomed to thinking in terms of spherocylindrical spectacle correction of naturally occurring refractive errors. We shall review traditional clinical optics and add to this framework current thoughts…

Introduction Refractive surgery procedures—including incisional radial keratotomy (RK), excimer laser photorefractive keratectomy (PRK), and laser in situ keratomileusis (LASIK)—are surgical procedures that cut, photoablate, or otherwise damage the cornea, resulting…