vision

At birth the eye of the normal full-term infant is approximately two thirds of adult size. In the infant the sclera (the "white" of the eye) is thin and translucent, with a bluish tinge. Growth of the eye is most rapid during the 1st year, proceeds at a rapid but decelerating rate until the 3rd year, and then continues at a slower rate thereafter until puberty. At puberty the eye is essentially its adult size.

The normal cornea - the tissue that lies in front of the iris and lens of the eye - is perfectly clear. In infants born prematurely there may be a transient opalescent haze in front of the iris.

The iris of white babies is typically light blue or gray at birth. It usually darkens to a greater or lesser degree as the pigmentation of the iris increases in the first six months of life.

The lens of the eye continues to grow throughout life; however with age, the lens becomes progressively more dense and more resistant to change of shape during accommodation. Hence the need for many of us over forty to wear bifocals.

Tears often are not present with crying until after 1-3 months.

Conjunctival hemorrhages - tiny broken blood vessels on the surface of the white of the eye - also may occur normally during all the commotion attending vaginal birth. These are resorbed spontaneously within a few weeks and are totally harmless.

The normal newborn can certainly see. The visual acuity in the newborn is estimated to be in the range of 20/400 - about like me with my glasses off. I can see well out to the distance of my bent elbow, but things are blurry beyond that. In other words, Baby sees Mommy and Daddy in sharp focus when held in the normal crook-of-the-arm position. As it should be, naturally.

As a rule, the infant eye is somewhat farsighted (hyperopic), but this is variable depending on the size of the eye, the exact curvature of the lens, and the curvature of the cornea.

Babies prefer to look at human faces, and especially Mother's face. During feeding, Baby usually studies Mother intently. By 2 weeks of age Baby shows more interest in large physical objects, and by 8-10 weeks the normal infant can follow an object visually from one side to the other of its visual field.

In many normal infants there may be some noticable misalignment of the eye movements during the early days and weeks, especially when the baby is tired. However, normal alignment should be achieved by 3-6 mo, usually sooner. Any eye misalignments present in a baby after that time should be referred to an eye specialist. I refer any baby over three months old with an eye deviation to the pediatric ophthalmologist for evaluation of possible strabismus and/or amblyopia.

Vision screening in the doctors office:

Preverbal children can be screened for visual acuity problems with a photographic screening device from about six months of age. We do this in our office, and I have been very satisfied with the device.
Visual acuity can usually be measured directly when children reach 2 1/2-3 years of age, using a picture eye chart.
The E test, in which the child points in the direction of the letter, is the most widely used visual acuity test for preschool children. This test can be performed by most children 3-4 yr of age, especially if they practice at home to become comfortable with "The E Game."
An adult-type Snellen vision chart can be used at about 5 or 6 years if the child knows letters. An acuity of 20/40 is generally accepted as normal for 3-yr-old children. At age 4, 20/30 is typical. By age 5 or 6, most children attain 20/20 vision, although we seem to measure 20/30 as an average for the kindergarten physical.

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