The visual system is the most complex sensory system in the human body. However, it is the least mature system at birth. Though they have the anatomical structures needed for sight, infants have not learned to use them yet. Much of their first weeks and months are spent learning to see. As children grow, more complex skills, like visual perception, develop.
Description
At birth, the sense of hearing is much more dominant than the sense of sight. Normal visual development is the change from just responding to simple brightness or high contrast, toward the organization of details into patterns and the ability to apply meaning to an object or picture.
Infancy
The following timeline discussion highlights some of the developmental milestones of vision development in a child's first year. Between birth and one month, a baby shows preference for familiar faces and objects, pays attention to the human face for short periods of time, has acuity of about 20/400 but can detect a black line on a white background that is only 1/16 of an inch (1.6 mm) wide, and possesses color vision, with the exception of blue.
At two months, a baby will visually lock onto a human face, watches people who are some distance away, is able to alternate his or her gaze between two people or objects, and demonstrates simple visual preferences.
Between four and six months, a baby is enthralled with other baby's faces, and he or she enjoys looking in a mirror. At this age the baby recognizes a person on sight and smiles. The baby also shifts from preferring what is familiar to that which is new, with the exception of people. The child will also look for objects when they fall from view.
From six to 12 months, a baby continues to "see" objects even when they are no longer visible. At this age, the baby also responds to words a parent uses to label familiar objects and people, by gazing in their direction.
Toddlerhood
After the first year, children's eyes and vision continue to develop. Their eye muscles gain strength, and the connections between nerves multiply. This development is aided by providing visual stimulation. Activities such as stacking building blocks, coloring, and cutting all assist in improving eye/hand/body coordination, eye teaming, and depth perception. By age three, most children have developed the necessary language and motor skills that allow them to participate in some traditional vision tests.
Preschool
During the preschool years, a child's vision keeps developing. The child develops visually guided eye/hand/body coordination, the fine motor skills and visual motor skills required for reading. The following can facilitate a preschooler's visual development:
reading aloud to the child and letting him or her see what is being read
providing a chalkboard or finger paints and demonstrating how to use them in play
allowing time for interacting with other children and for playing alone
School age
It is important that children have a complete eye examination before beginning school. The optometrist or ophthalmologist needs to determine if a child's vision is prepared to handle reading, writing, and other close-up activities. While toddlers use their eyes primarily for distance sight, school requires that the child's eyes focus on very close work for hours every day. This activity occasionally causes eye problems to arise. It is important to note that children rarely report vision problems. They believe their vision is normal and believe others see the way they do. The basic vision skills needed for school work are:
near vision (the ability to see clearly at 10–13 inches [25-32 cm])
distance vision (the ability to see clearly beyond arm's reach)
binocular vision (using both eyes together for depth perception)
focusing skills (the ability to keep both eyes accurately focused at the proper distance)
eye movement skills (the ability to aim the eyes accurately)
peripheral awareness (the awareness of objects located to the side while looking straight ahead)
eye-hand coordination
Common problems
Infants born prematurely have more difficulty integrating and interpreting visual information even when their acuity is normal. In some cases, children develop their visual reflex later than normal. This is called visual maturation delay. A condition, nystagmus, which sometimes develops in infancy, causes the eyes to jump, dance, wiggle, or oscillate. Babies with this problem may or may not have normal vision.
KEY TERMS
Nystagmus—An involuntary, rhythmic movement of the eyes.
Strabismus—A disorder in which the eyes do not point in the same direction.
Parental concerns
Parents need to assess their child frequently for any signs that the child's visual development is not progressing as expected. Some vision disorders are untreatable at later ages, so it is important to have the child seen by an optometrist or ophthalmologist no later than the age of three.
When to call the doctor
At the first signs of eye and vision problems, parents should consult their pediatrician, optometrist, or ophthalmologist. Some of these signs are:
eyes turned grossly in or out or which do not move normally before the age of three months
an eye that moves while the other remains still
an eye that appears considerably different from the other
the inability at three months of age of an infant to follow a toy passed in front of him from side to side
During the preschool years, parents should continue looking for signs that a vision development problem exists. These signs may include a short attention span for the child's age; difficulty with eye/hand/body coordination; or the avoidance of coloring, puzzles, and other activities.
A child should have his first eye exam by the age of three (or sooner if vision problems run in the family), so the practitioner can assess if vision is developing normally. Vision should be checked again when the child enters school.
Some of the signs of visual problems in the school age child are:
Since vision changes may occur without the parents or the child noticing them, a child should visit an eye doctor at least every two years, more frequently if specific problems or risk factors exist.
BOOKS
Marks, Paul. Through a Baby's Eyes: An Infant's Humorous Diary on the First Year of Life. Chula Vista, CA: Black Forest Press, 2004.
ORGANIZATIONS
National Eye Institute. 31 Center Drive MSC 2510 Bethesda, MD 20892–2510. Web site: <www.nei.nih.gov>.
WEB SITES
Glass, Penny. "What Do Babies See?" Vision Connection, December 3, 2004. Available online at <www.visionconnection.org/Content/ChildrensVision/AboutChildrensVision/AboutInfantsVision/WhatDoBabiesSee.htm> (accessed January 11, 2005).
