Good vision is important at any age, but it is particularly important during childhood development. Does your state require vision screenings for children? Many states have guidelines and requirements for these tests, but some do not.

It’s simple; a child having trouble seeing will likely have trouble learning. About one in four children in kindergarten through sixth grade and between five and 10 percent of pre-schoolers have an undetected vision problem.

Children with vision problems that are not corrected can fall behind in school. This can negatively impact the process of learning to read, among other critical skills—and it is important to intervene early. Research shows that pre-school children with uncorrected vision impairment—specifically hyperopia, or farsightedness—perform worse than their peers on reading tests.

Further, experts say that catching poor vision and eye health problems at the pre-school age or younger can prevent permanent damage, emphasizing the need for early exams.

While many children are screened for vision in school, it is vital to seek a professional, comprehensive eye exam. School screenings often only test for distance, when a vision problem can be more complex. A full exam can find issues such as “lazy eye,” swelling or cataracts.

What should you look for?

What are some of the signs your child might have trouble seeing? Squinting, headaches, eye rubbing and finger tracing while reading are among the signs that your child might not be seeing properly. Other things to look for include sitting close to the TV, closing one eye at times, light sensitivity, watery eyes and complaints of computer eye strain.

What does your state require?

While many states require screening to some extent, there is no uniform national standard on testing for vision or other eye problems. Some states recommend or require testing once a year, or not at all, and while some states might require screening for pre-school kids, some only mandate it for older students.

Check out this chart to learn more about your state’s guidelines. The American Optometric Association recommends that children have eye exams at six months old, then age three, and again before entering first grade.