BACKGROUND: Prevent Blindness America estimates more than 150 million Americans use glasses to correct refractive error problems like nearsightedness and farsightedness.

Problems seeing, especially due to refractive error, often start in childhood. Estimates by VisionQuest 20/20, a research project of the Amblyopia Foundation of America, show 5 million elementary school children in the U.S. have vision problems. Eighty percent of school children aren't receiving annual vision screenings.

TYPES OF PROBLEMS: Refractive errors are the most frequent eye problems in the United States.

Myopia, or nearsightedness, and hyperopia, or farsightedness, are the most common types. Nearsighted people see near objects clearly but have trouble seeing distant objects. Farsightedness does the opposite to a person's eyesight.

Other common vision problems include astigmatism, or uneven focus, and presbyopia, an age-related problem with focusing on near objects. Amblyopia, or "lazy eye," is a more serious vision problem that is the leading cause of single-eye blindness in the United States.

Most vision errors can be corrected with glasses. Surgery is now an option for certain types of vision problems.

DETECTION: The detection of eye problems is especially important in children since undetected problems can lead to long-term difficulties in school and social settings.

Traditional screening methods are administered in doctor's offices and schools.

A technique called photoscreening is especially suited to detecting amblyopia. It involves using a camera or video system to capture images detailed images of the eye. Since a child doesn't have to focus on a target like a chart, the test is easily administered. However, this technology is expensive, and results have to be sent in to be analyzed.

If problems are detected after tests like this, the child is sent to an eye doctor for further testing.

A FUN METHOD: A new eye test makes screening not only easy, but fun for kids.

The computer game Eye Spy helps medical professionals pinpoint vision problems like refractive error and amblyopia.

Children wear glasses with red and blue lenses while playing the game, which is a treasure hunt. The different-colored lenses ensure each eye is screened individually. Estimates show the game would cost about $5 per child. Professional eye exams can cost up to $75 per child.