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I still take off my glasses to read. I'm nearsighted, so when I was younger, I had excellent vision at close distances. I could read the microprint on checks. I could read the words around Lincoln's head on the five dollar bills, in the outer line that looks like a fuzzy blur now. But I'm over 50 years old, so my reading vision is declining.
Our eyes have two structures to refract light and focus images on our retina. Both are convex, so they bend light rays closer together. The cornea provides about two thirds of our focusing ability. The lens provides the other one third, and it can change shape to focus at different distances. Closer objects need more focusing power, so the lens becomes more convex when we view objects at reading distance. The lens changes to a thinner shape when we're driving or viewing other objects at a distance.
With age, the lens loses its elasticity and gets parked in the thinner shape. The minimum distance between eye and object, necessary to get it in focus, increases. Some people complain that their arms are not long enough, as they hold reading material further and further away.
Farsighted people have extra trouble with presbyopia. A young, farsighted person can focus on distant objects by making the natural lens more convex. He or she needs glasses only for close work. But when the lens loses its elasticity, then nothing is in focus, at any distance. These folks generally get bifocals, trifocals, or progressive lenses to compensate for what the natural lens is no longer able to do.
The bad news is, there's nothing you can do to stop this process. The good news is, you won't go blind from presbyopia. As long as the back part of your eyes (retina, optic nerve, etc.) works correctly, you can most likely get enough light focused in the right place with glasses, contact lenses, or refractive surgery. By age 65 or so, presbyopia stabilizes.
Bifocals and progressive lenses are popular for my age group. Refractive surgery, such as LASIK, can correct the distance vision so that we can get along with just single-vision glasses for reading and other close work. Some LASIK patients choose the monovision option, which means one eye is corrected for distance vision and the other for close vision. Glasses may still be necessary for some tasks, such as driving, but the vision improvement is enough to be attractive to many.
I'm in the baby boom generation, so I have plenty of company as my vision declines. I hope the optical industry continues to develop new products for us.
Sources:
Melvin L. Rubin, MD, et al, “Taking Care of Your Eyes”, Triad Publishing Co., 2003.
Linda Fugate is a scientist and writer in Austin, Texas. She has a Ph.D. in Physics and an M.S. in Macromolecular Science and Engineering. Her background includes academic and industrial research in materials science. She currently writes song lyrics and health articles.
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