The University of Arizona


The University of Arizona
Department of Ophthalmology and Vision Science

Infant Vision Testing Laboratory


Testing Infants' Acuity

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How do you test the visual acuity
of infants and young children?

When an adult goes to the eye doctor, visual acuity is tested with letters of different sizes.  We test young children's visual acuity by showing them  black-and-white stripes of different sizes, and watching to see if they look at the  stripes.

Vicki Showing Stripes Animated Photo

Vicki showing stripes.
(Animation may take a moment to download)

Young children tend to look toward stripes they can see.  When the stripes are thinner, children no longer look towards them, because the stripes appear to blend in with the gray background.  The narrowest stripes that a child will look at provide a measure of that child's visual acuity.  The results are then presented to the family.


We provide the family with the following data sheet and graph:


MAC Results
BAC Results


The graph =  The dotted lines on the graph show the normal range of visual acuity scores for children from newborn to 36 months old. The width of the stripes is listed up the left side of the graph (on the Y-axis), with thicker stripes near the bottom of the Y axis, and thinner stripes near the top of the Y axis.  Very small stripes, that an adult with 20/20 vision could see, are represented toward the top of the graph (around 32cycles/degree). We do not expect to find that level of visual acuity until somewhere between the ages of 3 and 5 years.  The dotted lines on the graph are showing the normal range of visual acuity scores for the different ages. The bottom dotted line is the lower limit of the normal range and the top dotted line is the upper limit of the normal range. If the data point for a given child falls within the dotted lines, that child’s score is in the normal range for their age.

Monocular Testing = Child was tested with one eye at a time.  Usually the right eye is tested first (left eye patched), and then the left eye is tested (right eye patched).

Binocular Testing =Child was tested with both eyes open.

Patient’s Name = Name of child being tested.

Test date = Date the child was tested.

Date of Birth = Date the child was born.

Age = Age of child in months ±2 weeks.

Cy/Cm = Cycles per centimeter refers to the size of the smallest stripes seen by child.  (Each cycle is one black and one white stripe.)

Distance = Distance between child and card (in centimeters).  Usually this is 38 centimeters for  children 6 months of age and younger, and 55 centimeters for children older than 6 months.

Cy/Deg = Cycles per degree also refers to the size of the smallest stripes seen by child.  Each cycle is one black and one white stripe. Degrees refer to degrees of visual angle.  One degree of visual angle is about the size of a thumbnail at arm's length.

Snellen = The Snellen scale is the most common scale used to represent acuity.  20/20 is normal vision in adults.  The values represented here are estimates of how the child would have scored on the Snellen scale.  It is important to remember that this is an estimation and not a direct conversion.  Snellen letter charts require a person to recognize letters while this method only requires that the child notices the stripes.

Confidence = Lower ratings are often given if the child is fussy or sleepy during the test.

Tested with correction = Was the child tested wearing glasses?


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