Babies have poor vision at birth but can see faces at close range, even in the newborn nursery. At about 6 weeks, a baby's eyes should follow objects, and by 4 months, should work together.

Over the first year or two, vision develops rapidly. A 2-year-old usually sees around 20/30, nearly the same as an adult.

Parents should be aware of signals of poor vision. If one eye turns or crosses, that eye may not see as well as the other eye. If the child is uninterested in faces or age-appropriate toys, or if the eyes rove around or jiggle (nystagmus), poor vision should be suspected.

Other signs to watch for are tilting the head and squinting. Babies and toddlers compensate for poor vision rather than complain about it.

Should a baby need glasses, the prescription can be determined fairly accurately by dilating the pupil and analyzing the light reflected through the pupil from the back of the eye. A baby's vision can also be tested in a research laboratory, where brain waves are recorded as the child looks at stripes or checks on a TV screen. The test is called Visual Evoked Potential (VEP).

Another test, called preferential looking or Teller Acuity Cards, uses simple striped cards to attract the child's attention. In both tests, as the stripes grow smaller, the child eventually does not respond (with brain waves for looking at the stripes.)

A common question for parents is: Why does my baby's eyes change color? When a baby is first born, the eye still has not fully developed a dark pigment known as melanin that helps “color” eyes and skin. Blue or gray eyes, which Caucasian babies have at birth, in a newborn mean that melanin is virtually absent with the eye's colored portion or iris.

When your baby is about 6 months old, you'll have a better idea of the eye color as pigmentation begins to form and brown or darker eyes might appear. The baby's eye color should be determined by about age 1, although some individuals may experience eye color change through adulthood. People of Asian, African American, Hispanic or Native American descent often have babies who are brown-eyed at birth because of darker pigmentation.

It's possible that having darker eyes and skin represents a higher amount of melanin and pigmentation, which may help protect eyes against eye diseases such as age-related macular degeneration. Darker eyes absorb more light rays that potentially might damage the light-sensitive inner lining of the eye where the retina and macula are located.

Mark DiVietro is an optician at Silbert Optical in Auburn.