The Correction Of Refractive Errors

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Before considering the correction of refractive errors, one must first understand the basics of the eye and how it uses the process of refraction to create visual images. The process of refraction begins with light as it comes in from external sources, with the amount of light being regulated by the pupil, the large, black, circular opening at the front of the eye. The size of one’s pupil is further regulated by the iris, the even larger, circular, colored part of the eye. Once light rays make contact with the eye, they hit the cornea, the clear, dome-shaped layer that covers the front of the eyeball. When the light rays hit the cornea, the cornea bends (or refracts) them in a primary stage which is followed up by the lens, a clear surface behind the pupil which further focuses the light rays (now becoming an image) onto another essential part of the eye: the retina, which is located along the back inside surface of the eyeball. “The retina is a thin, delicate, photosensitive tissue that contains the special “photoreceptor” cells that convert light into electrical signals” (“How we see”). These electrical signals act as messages that are further processed and then sent to the brain via the optic nerve, a bundle of nerves that connect to the back of the eye. When they reach the brain, the brain interprets them and they become the images that one sees. Therefore, at its core, vision truly comes from the brain. Within this basic process of refraction in the
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