Until recently, many people, even some experts, thought that infants could not see very well. This idea is not new. William James, the great 19 th century philosopher and psychologist, argued that the visual world of infants is a "booming, buzzing confusion."

So exactly what do infants see?

Let's first consider the focusing ability of infants or what we will refer to as the optical part of vision. When you try to look at an object, special muscles inside your eye called the ciliary muscles automatically contract or relax the shape of the lens of your eye so that a clear image is projected onto the seeing tissue of the eye called the retina. The retina lines the inside of the back of your eye. This is similar to adjusting the lens of a camera to get a clear photograph. Infants are born with the optical parts of their eyes fully capable of focusing on objects at any distance, from the horizon to objects right in front of their nose. Yet many sources about infant development still say that babies can only focus 7 to 10 inches from their face. We believe infants are able to focus at any distance however they just don't have very good control of their focusing muscles. This means that during the first 2 months of life they may not focus accurately. Sometimes they focus too close (in front of the object), sometimes too far (behind the object). After about 2 months of age infants begin to have better control and can focus clear images onto the retina.

Once an infant can focus detailed vision begins to develop. Visual acuity is dependent on the optical components of the eye (like the lens), but more importantly it is dependent on the functioning of the retina and the brain. This means that even though the optics of the eye are mature, infants still can't see as well as adults because brain areas responsible for vision are still immature. To use the camera analogy, the reason that infant's vision is blurry is because of the "film", not the lens. The retina (the film of the eye), in addition to other visual parts of the brain, are incompletely developed in infants.

The retina in each eye contains over 100 million cells that are extremely sensitive to light. The part of the retina that is specialized for good visual acuity (good detail vision), as well as for good color vision, is called the fovea. When we look at an object, what we are really doing is moving our eyes so that the image projected onto the retina falls on the fovea. The fovea is specialized for detailed vision. In young infants, visual acuity is limited, primarily because the fovea is immature. Thus, even when a young infant is able to focus a clear image on the retina, the fovea and other visual parts of the brain are too immature to transmit a clear image and even well-focused objects will remain blurry.

Research conducted a Smith-Kettlewell Eye Research Institute ( San Francisco ) and at the University Of California College Of Optometry ( Berkeley ), have measured visual acuity in many babies and toddlers. They found that in the first month of life, babies have a visual acuity of about 20/120. That means that if they could read, they would only be able to read the big "E" on an eye chart.

By 4 months of age, acuity has improved by a factor of 2, that is to 20/60 vision. By 8 months of age, the nervous system has matured enough to improve acuity by a factor of 2 again, that is to 20/30, and is now nearly as good as normal adult acuity (20/20). Over the next several years, acuity improves gradually to adult levels; but the most dramatic change is over that first 8 months.

We now know that a very young baby's acuity is at least 6 times less that an adult's visual acuity. Again, this is not because infants cannot "focus" well. Rather, it is limited by immaturities in the nervous and visual system. Nevertheless, they are still capable of having a rich visual world. Abnormalities in an infant's visual system need to be determined as early as possible to allow for adequate time to treat specific problems. Infants with large prescriptions need to be treated early in life to avoid developing "lazy eye" or amblyopia. In addition, evaluation of an infant's retina and optic nerve to rule out disease is equally important.

Cockrell Eyecare is proud to participate in a program called INFANT SEE. This program provides complimentary vision analysis for infants. Testing is all objective and very easy for the child to go through. If you have an infant we encourage you to call our office and schedule a complimentary vision analysis. Infants can be scheduled in Stillwater at 405-372-1715 or Pawnee at 918-762-2573. Visit our column next week for Part II of "What can my baby see?".