Vision correction surgery, also called refractive and laser eye surgery, is any surgical procedure used to correct vision problems. In recent years, tremendous advancements have been made in this field.
Most types of vision correction surgery work by reshaping the cornea, or clear front part of the eye, so that light traveling through it is properly focused onto the retina located in the back of the eye. Other types involve replacing the eye’s natural lens. There are a number of different types of surgery to improve vision, including:
Understanding Astigmatism -- the Basics
Most of the focusing power in the eye occurs along the front surface, at the cornea (the clear 'window' in the front of the eyeball), or within the lens, which sits behind the cornea inside the eye. The ideal cornea has a symmetrically curved surface, like a basketball. Astigmatism is caused by a cornea or a lens that is not symmetrical, like a football. The cornea is the transparent window in front of the colored part of the eye. It bends (refracts) light rays to focus the light onto the retina...
- LASIK: Short for laser in-situ keratomileusis, this laser eye surgery is used to correct vision in people who arenearsighted, farsighted, and/or haveastigmatism. During LASIK surgery, vision is corrected by reshaping underlying corneal tissue so that it can properly focus light into the eye and onto the retina. LASIK eye surgery differs from others in that a flap is made in the outer layer of the cornea so that the underlying tissue can be accessed. LASIK may also be done with the addition of computer imaging called wavefront technology to create a detailed image of the cornea and guide for treatment.
- PRK: Short for photorefractive keratectomy, this laser eye surgery is used to correct mild to moderate nearsightedness, farsightedness, and/or astigmatism. During PRK surgery, an eye surgeon uses a laser to reshape the cornea. This laser, which delivers a cool pulsing beam of ultraviolet light, is used on the surface of the cornea, not underneath a flap of the cornea, like in LASIK eye surgery. PRK may also be done with computer imaging of the cornea.
- LASEK: Short for laser epithelial keratomileusis, this is a variant of PRK. An epithelial flap is created and then epithelial cells are loosened using an alcohol solution. A laser is used to reshape the cornea, then the flap is replaced and secured with a soft contact lens while it heals. LASEK surgery is used to treat nearsightedness, farsightedness, and astigmatism.
- RLE: Short for refractive lens exchange and also known as clear lens extraction, RLE is similar to surgery done for cataracts and involves making a small incision at the edge of the cornea to remove the natural lens of the eye and replace it with a silicone or plastic lens. Also called PRELEX, clear lens exchange (CLE), clear lens extraction (CLE), and refractive lens replacement (RLR), RLE is used to correct extreme farsightedness or nearsightedness. It may be appropriate for people with thin corneas, dry eyes, or other minor problems of the cornea. To correct astigmatism, however, another procedure such as PRK, LASEK, CK, or Epi-LASIK may be needed in addition to RLE.
- EpiLasik: In EpiLasik, which is similar to PRK, a very thin layer is separated from the cornea and then the cornea is reshaped. The thin layer may be left off or replaced. The area is protected with a soft contact lens while it heals.
- PRELEX: Short for presbyopic lens exchange, PRELEX, is a procedure in which a multifocal lens is implanted to correct presbyopia, a condition in which the eye’s lens loses its flexibility, making it difficult to focus on close objects.
- Intacs: Also known as intracorneal ring segments, or ICR, this procedure involves making a small incision in the cornea and placing two crescent-shaped plastic rings at the outer edge or the cornea. The rings flatten the cornea, changing the way light rays focus on the retina. ICR was used to treat mild nearsightedness as well as nearsightedness but has been replaced by laser-based procedures. Irregular cornea shape from keratoconus, a condition that results in vision loss due to thinning and irregularity in the cornea, is the most common condition treated with intacs.
- Phakic intraocular lens implants: Designed for patients who are too nearsighted for LASIK and PRK, the phakic implant is inserted through a small incision at the edge of the cornea and attached to the iris inserted behind the pupil. This procedure differs from RLE in that the eye's natural lens is left in place.
- AK or RLI : Short for astigmatic keratotomy, this is not laser eye surgery, but a surgical procedure used to correct astigmatism. The cornea of people who have astigmatism is shaped like a football. AK or RLI eye surgery corrects astigmatism by making one or two incisions at the steepest part of the cornea. These incisions cause the cornea to relax and take a more rounded shape. This eye surgery may be used alone, or in combination with other laser eye surgeries such as PRK, LASIK, or RK.
- RK: Short for radial keratotomy, this eye surgery was once one of the most frequently used procedures to correct nearsightedness. However, since the development of more effective laser eye surgeries, such as LASIK and PRK, RK is rarely used today and is considered an obsolete procedure.
