Narrator: This is Science Today. About half of the world population is either nearsighted or farsighted. Another great percentage has astigmatism and everyone past the age of 45 will develop age-related loss of vision. Ophthalmologists at the University of California, Irvine are striving to get to the root of why these vision problems occur. Dr. Peter McDonnell says this includes trying to understand what it is about aging that causes a loss in the ability to read.

McDonnell: And our belief is by understanding actually why these happen, we can best target and create treatment to prevent them or to treat these problems. With patients who have trouble reading, we'll often to a procedure called monovision, where we correct one eye for distance vision and leave the other eye purposely somewhat nearsighted to allow the patient to read with that eye.

Narrator: This has proven very successful …

McDonnell: Eighty percent of people tolerate monovision very successfully and find that it most improves their lives in terms of minimizing their dependence on any corrective lenses.

Narrator: For Science Today, I'm Larissa Branin.