Older Eyes Get New Lease on Life
May 22, 2000 -- Find yourself getting farsighted as you get older? A new operation that reverses age-induced loss of close-up vision may offer patients a "fountain of youth for the eye," according to Gene W. Zdenek, MD.
Approximately 80% of people over age 40 require glasses or contact lenses to read comfortably, says Zdenek, an ophthalmologist in private practice in Reseda, Calif. At age 10, children can see small objects or print from two inches away. By age 30, they have to hold the same objects six inches away, and by 40 to 45, "we can no longer read comfortably at 12-16 inches," Zdenek says. It is around this time that most people start wearing glasses for reading and other close-up tasks.
This loss of close-up vision with age is called presbyopia. For many years, it was thought that presbyopia resulted from progressive hardening of the lens of the eye. However, in 1994, Texas researcher Ronald Schachar, MD, PhD, advanced the theory that the lens keeps growing throughout life, something like an onion that keeps adding new layers. This leads to crowding of the eye chamber and creates slack in the tiny, thread-like structures that connect the lens to the muscles that make it change shape to accommodate the visual demands we place on it.
Zdenek likens the process to pulling a wagon with a rope: "The wagon is the lens, your arm is the muscle, and the rope is [the thread]," he tells WebMD. "If there's too much slack in the rope, the wagon won't move when you move your arm."
Presbyopia differs from true far-sightedness, in which the eye or cornea is shaped abnormally.
The new procedure. known as scleral expansion band (SEB) surgery, involves placing four small plastic segments in the white of the eye, or sclera, to expand the space between the lens and the muscles that control it. This tightens the threads that connect the two, allowing the lens to once more respond to the muscles that make it move, as it did when the eye was younger.