Lasik Eye Surgery & How the Eye Works
Serving Seattle, Bellevue, Everett, Olympia, and Tacoma, WA
In deciding whether to undergo ASA or LASIK eye surgery, it is helpful to understand how the eye works. It is like a camera.
- The cornea is a clear, dome-shaped window that forms the front wall of the eye. It is translucent, meaning that it allows light to travel through it into the eye. Being curved, it bends those light rays as they travel in, and lets them pass to the lens.
- The pupil opens and closes like a camera aperture, opening in dim conditions to allow more light in, and closing in bright light to protect the eye.
- The lens, sitting behind the iris (colored part around the pupil) further bends the incoming light rays so that they come to a focus on the retina.
- The retina is the light-sensitive tissue in the back of the eye. It acts like the film in a camera and receives the information carried in by the light rays. It converts it from image data to neural data.
- The optic nerve travels from the retina to the brain and carries neural information to the brain’s vision center.
- The brain interprets this neural information as images and finds names for them.
Refractive power
Refraction means bending of light. The cornea’s curvature determines its refractive power. Every human eye is different. Your two corneas are different and if you have vision correction surgery, each treatment will be different. Each cornea has curvature characteristics which can be measured and recorded by modern-day computerized ophthalmological technology.
In a 20/20 eye, light is refracted (bent) by both the cornea and lens such that it focuses clearly on the retina and you see clearly at all distances. When light does not focus clearly on the retina, the eye is said to have a refractive error. When a refractive error is present, corrective lenses (such as eye glasses or contacts) or refractive surgery (such as LASIK) can be employed so that incoming light rays become focused onto the retina to again produce clear vision.
Why doesn’t light focus on the retina?
In an eye with refractive error, the light is either:
- Bent too much (by a cornea that’s too steeply curved) and focuses in front of the retina. This is nearsightedness.
- Bent too little (by a cornea that’s too flat) and focuses behind the retina. This is farsightedness.
- Bent in several different ways (by a cornea with irregular curvature) and focuses in several different places, on or not on the retina. This is astigmatism.
What LASIK does
The LASIK laser reshapes the cornea. The lens does not need to be reshaped, as it continually reshapes itself as your eyes switch from the horizon to the computer to your fingernails and back again. Reshaping the cornea changes the angles at which it refracts light, so that what the lens does is exactly right to make clear images on the retina.
Throughout our lifetime
Our eyes change as we age. Our vision slowly deteriorates for various reasons, and Lasik Surgeon Dr. Leavitt offers various treatments to improve it at different stages of our life.
In young eyes – We can do full correction for all distances in both eyes
In middle-aged eyes – We can treat presbyopia with an intraocular lens, blended vision LASIK, or Conductive Keratoplasty.
In old eyes – we can treat cataracts with an intraocular lens
Please see Refractive Eye Errors and Other Eye Conditions for more information.
Perhaps you have been wondering whether you are a good candidate for LASIK vision correction. If so, please contact our Lasik surgeon to schedule an initial consultation. We are located in the Seattle, WA. area. Both Dr. Leavitt and his highly-qualified eye surgery staff will be glad to answer your Lasik questions. We hope to meet with you soon.