Vision Tests

Vision tests check many different functions of the eye. The
tests measure your ability to see details at near and far distances, check for
gaps or defects in your field of vision, and evaluate your ability to see
different colors.
Visual acuity tests are the most common tests used to
evaluate eyesight. They measure the eye’s ability to see details at near and
far distances. The tests usually involve reading letters or looking at symbols
of different sizes on an eye chart. Usually, each eye is tested by itself. And
then both eyes may be tested together, with and without corrective lenses (if
you wear them). Several types of visual acuity tests may be used.

Refraction is a test that measures the eyes’ need for
corrective lenses (refractive error). It is usually done after a visual acuity
test. Refractive errors, such as nearsightedness or farsightedness, occur when
light rays entering the eye can’t focus exactly on the nerve layer (retina) at
the back of the eye. This causes blurred vision. Refraction is done as a
routine part of an eye examination for people who already wear glasses or
contact lenses, but it will also be done if the results of the other visual
acuity tests show that your eyesight is below normal and can be corrected by
Visual field tests are used to check for gaps in your side
(peripheral) vision. Your complete visual field is the entire area seen when
your gaze is fixed in one direction. The complete visual field is seen by both
eyes at the same time, and it includes the central visual field-which detects
the highest degree of detail-and the peripheral visual fields.
Color vision tests check your ability to distinguish colors.
It is used to screen for color blindness in people with suspected retinal or
optic nerve disease or who have a family history of color blindness. The color
vision test is also used to screen applicants for jobs in fields where color
perception is essential, such as law enforcement, the military, or electronics.
Color vision tests only detect a problem-further testing is needed to identify
what is causing the problem.


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