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Visual Acuity

Visual acuity is the sharpness or clearness of vision. It is
the ability of the eyes to see fine detail and is determined
by how effectively light is focused in each eye.

Testing distance visual acuity is a common measure of
eyesight. It involves reading the letters on an eye chart
across the room. A reduced eye chart can also be used to
measure near visual acuity at normal reading distances.

The level of visual acuity is written as a fraction such as
20/40. The top number in the fraction is the standard
distance at which testing is done, twenty feet. The
bottom number is the smallest letter size the child was
able to read.

Normal distance visual acuity is 20/20. A child with
20/40 visual acuity would have to get within 20 feet of a
letter that should be seen as far away as 40 feet in order
to see it clearly.

If a child has less than "normal" or 20/20 visual acuity,
he or she may have difficulty copying from the
chalkboard or watching a movie in class. Unfortunately,
this is often the only visual ability tested during a school
vision screening. While it is important, having 20/20
visual acuity does not mean a person has "perfect"

Other vision skills such as eye focusing, eye teaming and
eye tracking are needed in the classroom and on the
playground. So even if you child passes a vision screening
or eye test with 20/20 visual acuity, don't assume he or
she doesn't have a vision problem.
Vision Topics