PRK (Photorefractive Keratectomy) is a vision correction procedure which uses a laser to reshape the cornea. and takes just a few minutes and is done under topical anesthesia.
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: They are 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.
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To treat nearsightedness, the cornea is made flatter by removing tissue from the center of the cornea.
To treat farsightedness, the flat cornea is made steeper by removing peripheral tissue in a ring shape on the outer edges of the cornea. This steepens the central visual part of the cornea.
To treat astigmatism, the cornea is made less oval shaped. Astigmatism means that the eye has an oval or football shape.
The laser reduces the oval shape making the focusing ability clear in all directions. Astigmatism can be treated at the same time as nearsightedness and farsightedness