Your vision is a precious and essential part of your life, and your eyes are marvelous, complex instruments. In fact, your vision is made possible by the interaction of many components.
Cornea · A curved band of strong, clear tissue on the surface of the eye, the cornea focuses light onto the retina.
Epithelium · The epithelium provides a thin protective layer for the cornea and heals very quickly when disturbed.
Iris · The colored part of your eye is actually a muscle that controls the size of the pupil.
Pupil · The black circular area in the middle of the eye controls the amount of light reaching the retina.
The Natural Lens · A natural lens behind the pupil changes shape to allow the eye to focus. As you age, your natural lens cannot change shape, resulting in presbyopia—the loss of reading vision.
Sclera · The outer white coat of the eye, the sclera also provides protection.
Retina · A membrane on the inner wall of your eye, similar to the film in a camera, the retina changes light into images that are transferred to the brain via the optic nerve.
One of the most important components of your eye is the cornea—the "window" of your eye. The job of the cornea is to bend, or refract, light rays so that they focus on the retina. At the Herzig Eye Institute, LASIK vision correction is used to improve a number of these refractive conditions.
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You may be familiar with the term myopia, also known as near-sightedness. Myopia is the result of an eyeball which is too long, or a cornea which is too curved. In both cases, light rays entering your eye fall short of the retina, and objects in the distance appear blurred. If you have this condition, you are not alone; more than 70 million people in North America have myopia.
Astigmatism occurs when your cornea is shaped like a football, with two different curvatures. Images appear blurred or ghost-like because light rays are refracted unequally. In extreme cases, images both near and far appear blurred. Many people who have myopia also have astigmatism.
Hyperopia, or far-sightedness, is the opposite of myopia. Here, your eye is too short or your cornea is less curved. Consequently, light rays entering your eye fall behind the retina. This results in blurred vision which is worse at near distances than far.
Presbyopia is the term used for the loss of reading vision that everybody experiences after age 40. Typically, one wears reading glasses or bifocals to compensate for the loss of reading vision.
When laser vision correction is performed, patients can choose to preserve some of their near vision by having their non-dominant eye left mildly nearsighted. This is called monovision and is a very successful approach to providing patients with both distance and reading vision.
A more recent advance in the laser treatment of presbyopia involves creating both a distance and reading area on the cornea with the laser so that both eyes can see in the distance equally, as well as continue to read. At present, this is still undergoing clinical investigation and is available to a small group of qualifying patients.
