How the Eye Works
We want you to know as much as possible about how your eyes work, and especially why they sometimes do not work as well as they should.
Whether you are searching for answers to a current vision problem or are simply curious about your eyes, we hope that you find the information presented here useful. But remember, it is not a substitute for a professional eye exam. We welcome you to give us a call if you have a question about your vision.
Normal Eye
The eye’s surface is convex, and light rays that hit it bend toward its center. In an eye that has the correct shape, an image focuses exactly on the retina, the inner surface of the back of the eye.
How the Eye Works
Nearsightedness (Myopia)
When the eyeball is too long from front to back, light rays focus in front of the retina, rather than on it. Near objects are seen clearly, but distant objects are not.
Nearsightedness: Overview
Farsightedness (Hyperopia)
When the eyeball is too short from front to back, light rays entering the eye focus behind the retina. Distant objects are seen clearly, but near objects are not.
Farsightedness: Overview
Astigmatism
Ideally, the surface of the cornea is uniformly rounded, like the smooth, even surface of a ball. Vision becomes distorted when the surface of the cornea has an uneven curvature, rounded more like the back of a spoon than the surface of a ball. This type of irregularity causes blurred vision because light focuses on more than one spot on the back of the eye. Have you ever looked through a pane of glass that has an irregular, somewhat wavy surface? That uneven surface allows only one part of the view to be in good focus—the rest is blurred and wavy-looking.
Astigmatism: Overview
Presbyopia (Loss of Reading Vision)
The lens of a youthful eye flexes to change shape (“accommodate”) when we change from focusing on something in the distance to something closer, like a book. Over time, the eye’s lens gradually loses its flexibility and ability to change shape to see close objects. Bifocals or reading glasses are the traditional prescription for remedying this “presbyopic” loss of accommodation.
However, modern technology has made it possible to exchange the eye’s inflexible natural lens for a “lifestyle lens” designed to compensate for these cheangs in the eye and improve functional vision at all distances.