Nearsightedness

Science World, Feb 7, 2005 by Elizabeth Carney

If you squint to read the chalkboard from the back of the classroom, a new option may keep you from having a four-eyed future.

With a novel surgical procedure, doctors can implant tiny lenses directly into a patient's eyes. The result? Nearsighted people, those who struggle to see far away things, get a new look at life. The implants, called intraocular lenses, are the latest addition to a list of treatments that allow folks to toss their frames into the trash.

Unlike Lasik laser eye surgery, which reshapes part of the eye, the new technique relies on thinner than-paper corrective lenses. After cutting a slit in the eye, a surgeon tucks the plastic lens between the patient's cornea (eye's clear outer covering) and the eye's natural lens.

As light bouncing off an object passes through the implanted lens, the rays spread slightly outward. That way, when the light passes through the eye's natural lens, it will be focused directly on the retina, the back part of the eye that's sensitive to light, rather than in front of it (see diagram, right). All corrective lenses, such as glasses and contacts, work in a similar way. "The implants are like contacts inside your eye," explains Aaron Fay, an eye surgeon at Harvard Medical School. The procedure is also reversible. So if a person doesn't like the implants, doctors can remove them.

Still, the new lenses aren't for everyone. They are meant to help severely nearsighted people whose vision is so poor that laser eye surgery wouldn't work well. Are many people candidates? Nearsightedness, or myopia (my-O-pee-uh), is a common problem. An estimated 25 percent of Americans are nearsighted, including many teens and children. Of those, only about 3 million people have poor enough vision to be considered for the new eye surgery.

Nicole Kayse, an eighth-grader from Greenville, South Carolina, has had myopia since the age of six. She said that she would consider this eye surgery if her eyesight keeps getting worse. "I even need a new prescription now," she says. But Fay warns, "All surgeries carry some degree of risk."

Eye doctors once thought that nearsightedness was always passed on through genes (units of hereditary material). But now, some experts think that certain activities, such as reading in dim light, can worsen myopia. Nicole agrees with that theory.

"Before I went to bed, I used to read with only the closet light on," she says.

How can you avoid nearsightedness? "Myopia isn't preventable, but it's [still] important to use common sense to protect your eyes," says Fay. Some advice: Read and do homework in well-lit areas and take frequent breaks from computer work. Remember to rest your hardworking peepers!

Did You Know?

* The eye works similarly to a camera. When light bounces off an object and passes through the lens of a camera, it is recorded on film or a computer chip as an image. In the eye, after light goes through the lens, the retina records the image.

* When an image hits the retina of an eye, it's upside down. The retina converts the image into an electrical impulse that travels along the optic nerve to the brain. Your brain flips the image, letting you see it right side up.

Resources

* Learn about different types of vision-correction surgery at: www.medern.com/MedLB/articleslb.cfm?sub_cat=2016

* For basic information on how the eye works, visit the Wake Forest University Eye Center: www.bgsm.edu/eye/cornea/eyework2.htm