Confrontation tests and Amsler grid tests take just a few minutes. More
thorough visual field testing that uses perimetry and tangent screens can take
more than 45 minutes when both eyes are tested.
Color vision test
People who have normal color
vision are able to distinguish the colored numbers, symbols, or paths from the
background of colored dots.
If you are not able to distinguish
some or all of the colored patterns from the background, you may have a color
vision problem. You may be able to pick out some patterns of colors but not
others, or you may be able to pick out patterns that are different from a
person with normal vision, depending on what type of color vision problem you
This test takes only a few minutes.
Many conditions can change your vision test results.
Your health professional will discuss any significant abnormal results with you
in relation to your symptoms and past health.
What Affects the Test
Reasons you may not be able to
have the test or why the results may not be helpful include:
- Your ability to understand or follow
instructions. Some vision tests cannot be done on babies, small children, or
people who cannot understand or follow the instructions.
ability to stay alert and respond to questions.
- Failure to wear
prescribed eyeglasses or contact lenses.
- Poor lighting.
What To Think About
- Eye charts that use pictures or symbols (such
as an E chart) may be needed to test children or people who cannot read. Vision
tests are also available for babies and young children.
- A complete eye and vision evaluation also
includes a physical examination of the structures inside the eye. To learn more, see the topic
- A test to screen for
increased intraocular pressure (IOP), which increases your risk for
glaucoma, is often part of a routine eye exam. It also
is used to monitor treatment for glaucoma. Tonometry can be used to determine
whether a medicine is keeping your IOP below a set target pressure determined
by your doctor. To learn more, see the topic
- Home tests for near vision in
adults and distance vision in children are available. These tests should not
replace a thorough eye examination by a health professional.
Other Works Consulted
Chernecky CC, Berger BJ (2008). Laboratory Tests and Diagnostic Procedures, 5th ed. St. Louis: Saunders.
Fischbach FT, Dunning MB III, eds. (2009). Manual of Laboratory and Diagnostic Tests, 8th ed. Philadelphia: Lippincott Williams and Wilkins.
|Primary Medical Reviewer||Kathleen Romito, MD - Family Medicine|
|Specialist Medical Reviewer||Christopher J. Rudnisky, MD, MPH, FRCSC - Ophthalmology|
|Last Revised||June 9, 2011|