Refractive Surgery & Eye Errors
Serving Seattle, Bellevue, Everett, Olympia, and Tacoma, WA
Myopia (nearsightedness)
In the normal eye, the cornea and lens together focus light rays directly on the retina, resulting in clear vision without eye glasses or contact lenses. In myopia, or nearsightedness, we can express the problem in two ways. Either:
The eye is too long, front to back, for the steepness of its corneal curvature; or
The cornea is too steep for the length of the eye
The light rays are being bent too much and are focusing in front of the retina. Therefore, what reaches the retina is out of focus; but this is the information carried by the optic nerve to the brain. It is incomplete information, and the brain cannot give you clear images. Distant objects are blurred while nearby objects can be clear. LASIK can correct myopia by flattening the cornea so that its curvature is in the proper relationship to the eye’s length.
Hyperopia (farsightedness)
Hyperopia is the opposite of myopia. So we can think of it in two analogous ways. Either:
- The eye is too short for the flatness of its corneal curvature; or
- The cornea is too flat for the shortness of the eye
The light rays are being bent too little and are focusing behind the retina.
Nearby objects can appear blurry, while distant objects are clearer. Very farsighted patients will report that even distant objects appear blurry. Laser eye surgery can correct hyperopia.
Astigmatism
In the normal eye, the cornea is round. It is curved the same in horizontal and vertical directions, like a baseball. When the light rays are bent by the cornea, they focus at a single point.
In an astigmatic eye, the cornea is oval. It is not curved the same in horizontal and vertical directions. It looks like the side a football, with a steeper curve in the vertical axis and a flatter curve in the horizontal axis. When the light rays are bent by this cornea, they focus at two different points, causing distorted vision. Many people with myopia or hyperopia also have some degree of astigmatism. Laser eye surgery can correct all three conditions.
Presbyopia: not a refractive error, but correctable by Monovision LASIK
As we age, the crystalline lens of the eye loses its ability to focus on nearby objects. This condition, known as presbyopia, usually begins around the age of 40, and can most often be comfortably corrected through the use of eye glasses. ASA or LASIK will not prevent it but can compensate for it.
If you have been wondering whether you are a good candidate for LASIK vision correction, the best way to find out is to contact our Lasik eye surgeon to schedule an initial consultation. We are in the Seattle, WA. area. Both Lasik Eye Surgeon Dr. Leavitt and his highly-qualified staff put a high value on patient education and can give you clear answers to your questions.