September is a perfect month to have your child's vision checked. More than 12.1 million school-age children, or 1 in 4, has a vision impairment. Among preschool-age children, one in 20 has a vision problem that can cause permanent sight loss if left untreated. The most common types of eye problems in children are myopia (nearsightedness), strabismus (crossed eyes), and amblyopia (lazy eye).

A person who is nearsighted (or myopic) can not see things at a distance but can see up-close. Myopia occurs when the eyeball is slightly longer than usual from front to back. This causes light rays to focus at a point in front of the retina, rather than directly on its surface. Nearsightedness may be corrected with glasses, contact lenses or refractive surgery (in adults).

Strabismus is a condition in which the eyes don't work together. One eye moves normally, while the other points in (esotropia), out (exotropia), up (hypertropia), or down (hypotropia). Unequal pulling of muscles on one side of the eye or a paralysis of the ocular muscles may cause strabismus. Occasionally, a farsighted child tries to focus to compensate for the farsightedness and develops accommodative strabismus. Newborns often appear to have crossed eyes due to a lack of developed vision, but this disappears as the infant grows. True strabismus does not disappear as the child grows. The earlier the diagnosis and treatment, the better the visual results. Treatment for strabismus includes glasses to aid in proper focusing, eyedrops to help focus, and/or surgery.

Amblyopia, also known as "lazy eye," is a vision problem in which one eye has poor visual acuity. Although the amblyopic eye has the capability to see, the brain turns off this eye because vision is very blurred. The brain elects to see only with the stronger eye. An uncorrected refractive error (nearsightedness or farsightedness), strabismus and trauma can cause amblyopia. It's important to correct amblyopia as early as possible, before the brain learns to entirely ignore vision in the affected eye. Patching the unaffected eye to force the amblyopic eye to work, atropine drops, glasses or surgery (in the case of strabismus and amblyopia) may treat amblyopia.

Even if you don't observe any problems regarding your child's eyesight, you should have your child's vision checked by an eye doctor at 6 months, 3 years and before kindergarten.