ANATOMY OF THE EYE
Understanding the anatomy of the eye and the way the eye works may be helpful in understanding laser vision correction.
LASIK and PRK procedures reshape the cornea, the clear surface on the front of the eyeball. The cornea contributes significantly to the focusing power of the eye. Most of the cornea is made up of the stromal tissue layer. This layer does not regenerate once removed. The excimer laser produces a gentle beam of light that removes microscopic layers of the stroma. This process, known as photoablation, changes the shape of the cornea, resulting in an image that is more finely focused on the retina. This means that we can promote a permanent reshaping of this tissue, which results in an increase in the ability of your eye to focus without spectacles.
The individual components of the eye work in a manner similar to a camera. Each part plays a vital role in providing clear vision. Light rays enter the eye through the transparent cornea, which takes rays of light and bends them through the pupil, the dark, round opening in the center of the colored iris. The lens of the eye is located immediately behind the pupil. The purpose of the lens is to make adjustments in the path of the light rays in order to bring the light into focus upon the retina, the membrane that lines the inside back wall of the eye. The cells of the retina send the information brought by the light to the visual processing areas of the brain where an image is perceived.
As mentioned before, the cornea is a major focusing component of the eye. When the cornea is shaped in a way in which light is not focusing on the retina, there is a refractive error and the vision is not clear. With a change in the shape of the cornea we can correct this refractive error. The light can then become focused on the retina to produce clear vision.