Refractive Eye Surgery
Many people rely on glasses and contacts to correct their vision, but some find these methods inconvenient, uncomfortable or unattractive. Refractive eye surgery is a general term for a number of vision correction surgical procedures that can improve or correct the eye’s focus by permanently changing the shape of the cornea. The cornea is the clear, front surface of the eye which bends or refracts light rays as they enter the eye.
For you to see clearly, light rays must be focused by the cornea and lens to fall precisely on the retina, a layer of light sensing cells that lines the back of the eye. The retina converts the light rays into impulses that are sent through the optic nerve to the brain, which interprets them as images.
This process is very similar to the way a camera takes a picture. The cornea and lens in your eye act as the camera lens. The retina is similar to the film. If the image is not focused properly, the retina or film receives a blurry image. This condition in the human eye is known as a refractive error.
There are four types of refractive errors that can be corrected or reduced by refractive surgery.
For nearsighted people, close objects appear sharp, while images far away are blurred. The eyeball in nearsighted people is longer than normal from front to back, causing images to focus in front of the retina instead of on it.
In farsighted people, the opposite is the case. Objects far away are clear, while objects up close are blurred. Because the eyeball is shorter than normal, images focus behind the retina instead of on it.
For people with astigmatism, objects are blurred at any distance. In astigmatism, the cornea or lens (or both) is incorrectly shaped and cannot produce sharply focused images on the retina.
Usually occurring between the ages of 40 and 50, and as part of the natural aging process, the eye loses its elasticity and ability to change focus. As with astigmatism, images appear blurry.