The Eyes Have It

Detecting infant vision problems

While many vision problems begin in early infancy or before, they often are not recognized until a child has reached school age, when it may be too late to correct the problem.

Sight and the brain

In infancy and throughout the preschool years, seeing is understanding. More than 75% of infant learning occurs through the eyes: children learn what to do, and how to act, by watching others. Learning to read facial expressions and body language, and to respond appropriately, takes place in these early years. What children observe through their eyes forms much of the foundation of their social communication skills.

During these first years, a child’s rapidly developing brain responds to its environment, turning on and off capacities according to the various demands the body makes on it. If, for example, a child is less able to focus with one eye than the other, as in amblyopia, or “lazy eye” (a condition affecting 3–5% of all children), the child’s stronger eye becomes dominant. Gradually the child’s brain loses its ability to interpret visional information from the weaker eye. Without early detection and intervention—by patching the stronger eye so that the child uses and strengthens the weaker eye—irreversible vision loss can occur.

Asking before being told

To prevent potential vision loss or resulting delays in cognitive and social development, it is vital to know if an infant’s vision is developing normally and, if not, to take steps to resolve the problem as soon as possible. Early detection provides the best opportunity to repair problems and prevent permanent changes.

Unfortunately, babies can’t tell us when they don’t see properly. Even highly verbal preschoolers who tell their parents everything may not say a word about poor vision. Young children know only what they see, rather than what they “should” see. A child assumes that the world sees as he does, not realizing that everyone else sees the leaves in the trees, rather than large fuzzy green balls. How can vision problems be detected in very young children who can’t yet talk, read, or understand that they see differently?

Screening methods

The first step in examining an infant or toddler’s vision is to review the baby’s family history of vision problems for potential genetic issues. Pediatricians then perform a thorough external examination of the eyes and eyelids. Vision testing includes a series of exercises, such as following a dot of light, to ensure that the eyes are aligned and the lenses are not blocked.

If an initial screening suggests that a child is at risk for vision problems, pediatricians may refer families to an ophthalmologist for further evaluation. These eye and vision specialists may employ ocular photoscreening, an alternative testing method for children who cannot read an eye chart or sit still long enough for physical testing. This method measures a child’s visual reflexes and eye alignment. A preverbal child simply needs to fixate on the appropriate target for a few seconds for the photoscreening process to take place.

Another emerging technology that holds promise for wide-scale testing of infants and other nonverbal and preliterate children is the Pediatric Vision Screener (PVS). This recently developed screening instrument verifies the ability of both eyes to focus on a target at the same time. Children between 2 and 4 years old with lazy eye or other issues can have the problem detected in this way long before they are able to tell us and in time for the problem to be repaired successfully. The device is now being tested with children as young as 12 months.

Screening for all

While these screening technologies continue to develop, wide-scale efforts to screen all toddlers and preschoolers for vision problems are underway. Whether screening is performed in a pediatrician’s office or at a childcare center or preschool, it is essential that parents insist on early and regular assessments for their young children.

Sources: Pediatrics 109 (2002): 524–25; Pediatrics 105 (2000): 1292–98; Insight 30 (2005): 17–20; American Academy of Pediatrics Policy Statement (2003): 860–65; Journal of Pediatric Ophthalmology and Strabismus, 42 (2005): 103–11.

SIDEBAR:

All too common

Vision disorders are the fourth most common disability among children in the United States and the leading cause of impaired conditions in childhood. Recent studies estimate that only 21% of all preschool children are screened for vision problems, and only 14% receive a comprehensive vision exam. Eye exams are recommended for all children beginning in the newborn period and continuing with every checkup.

Source: American Academy of Pediatrics,  www.medicalhomeinfo.org/screening/vision.html

What causes poor vision?

Vision impairment can be caused by any damage to the eye that affects its ability to receive or process visual information. Poor vision can be due to the eye being shaped incorrectly, which can make it harder to focus on things. It can also occur

if the brain does not process visual information correctly. Vision problems can occur anytime during a person’s life, even before birth. Poor vision in children under the age of 10 years is most commonly due to premature birth, as children who are born very early, or who have very low birth weight, are most at risk for retinopathy of prematurity, an abnormal blood vessel growth or scarring of the retina of the eye.

The Parent Review newsletter publishes the latest research findings in child development, learning, and health. Written for expectant and new parents and the professionals supporting them, The Parent Review bridges science and parenting to offer the best and most relevant research-based news. To learn more, visit www.theparentreview.com.

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