Back-to-school means new notebooks, bright white tennis shoes and 180 days of reading, writing and arithmetic. Now that the kids are heading back to the classroom, make sure to check one more thing off your list: an eye exam.

The Sight & Hearing Association, along with experts at the American Academy of Ophthalmology, recommend that school-age children have a complete medical eye exam by age 4 and routine eye exams every two years thereafter.

In Minnesota, it's mandatory for children entering kindergarten to have both their vision and hearing checked. However, statistics prove the earlier the child is tested the better. That's the reason behind the Sight & Hearing Association's Preschool Screening Program. Screeners from the Sight & Hearing Association test 3-, 4- and 5-year-olds in the Minneapolis/St. Paul metro area for vision and hearing problems. Often, if problems are caught before the age of 6, they can be treated. Check with your state's department of health to find out the ages your child will be screened at school.

According to Dr. Evan Ballard, a pediatric ophthalmologist with Associated Eye Physicians and Surgeons in St. Paul, parents should be aware of signs that may indicate their child has vision problems. Warning signs include wandering or crossed eyes, a family history of childhood vision problems, disinterest in reading or viewing distant objects, and/or squinting or turning the head in an unusual manner while watching television.

Those signs may indicate one of the following eye problems common in children:

• refractive errors - eye conditions that can cause eye strain or a decrease in vision. They are corrected by wearing glasses or contact lenses. Hyperopia (farsightedness or the inability to focus on objects at close range) can cause children to cross their eyes. Myopia (nearsightedness or the inability to see clearly at a distance) is relatively uncommon before a child reaches fourth grade.
• amblyopia - commonly called "lazy eye," this condition occurs when vision develops abnormally during early childhood. Amblyopia is when one eye develops good vision while the other does not. It can result from a number of underlying causes and is often difficult to detect without a screening. Glasses or eye-strengthening patches are used for treatment.
• strabismus - a misalignment of the eyes, which causes them to point in different directions. Strabismus is a common condition, affecting about 4 percent of all children in the United States. Glasses or an eye patch are used to treat strabismus, but surgery may be required in some cases.