Origin of Vision Errors
The cornea is a part of the eye that helps focus light to create an image on the retina. It works in much the same way that the lens of a camera focuses light to create an image on film. The bending and focusing of light is also known as refraction. Usually the shape of the cornea and the eye are not perfect and the image on the retina is out-of-focus (blurred) or distorted. These imperfections in the focusing power of the eye are called refractive errors. There are three primary types of refractive errors: myopia, hyperopia and astigmatism. Persons with myopia, or nearsightedness, have more difficulty seeing distant objects as clearly as near objects. Persons with hyperopia, or farsightedness, have more difficulty seeing near objects as clearly as distant objects. Astigmatism is a distortion of the image on the retina caused by irregularities in the cornea or lens of the eye. Combinations of myopia and astigmatism or hyperopia and astigmatism are common. Surgical procedures aimed at improving the focusing power of the eye are called refractive surgery.
Types of Corrective Laser Eye Surgery
LASIK (Laser-Assisted In Situ Keratomileusis) is a procedure that permanently changes the shape of the cornea, the clear covering of the front of the eye, using an excimer laser. A knife, called a microkeratome, is used to cut a flap in the cornea. A hinge is left at one end of this flap. The flap is folded back revealing the stroma, the middle section of the cornea. Pulses from a computer-controlled laser vaporize a portion of the stroma and the flap is replaced.
PRK (Photorefractive Keratectomy) starts with the removal of a portion of surface of the cornea or epithelial tissue. There is therefore no need for flap creation, and the removed tissue grows back. Some patients prefer PRK because they don’t want a corneal flap, and some patients are better candidates for PRK eye surgery than for LASIK (for instance, people with thin corneas). Once the epithelium is removed, a laser is used to reshape the cornea. The excimer laser is used in both PRK and LASIK.
At Suggs Eye Center, the goal is to achieve 20/20 vision for every patient. As with any surgical procedure, results cannot be guaranteed. The results of laser vision correction have been overwhelmingly successful in eliminating or reducing the need of glasses or contact lenses. In a recent study, 98% of patients treated for nearsightedness and/or astigmatism achieved 20/40 vision or better. This means that you can legally drive, play sports, and join the police or fire department without depending on corrective eyewear.