When incoming light rays are focused perfectly onto the retina, the patient is called emmetropic, or having no glasses prescription. When these light rays are focused elsewhere (either in front of or behind the retina), the patient is said to be ametropic and have a refractive error. The most common forms of ametropia are myopia (“near-sighted”), hyperopia (“far-sighted”), and astigmatism. A glasses or contact lens prescription is required to manipulate incoming light rays such that they are focused perfectly onto the retina.
Patients who are frustrated with use of glasses or contact lenses have alternative options to correct their refractive errors, whether they be near- or far-sighted. The advent of modern refractive surgery occurred with LASIK (laser-assisted in-situ keratomileusis) and PRK (photorefractive keratectomy). Since the late 1990s, tremendous improvements in the process and outcomes of refractive surgery have been made.
The most common refractive procedures in the modern era are LASIK, PRK, refractive cataract surgery (“clear lens exchange”), and implantable contact lens (ICL) surgery.