What is the Visual Acuity Test?
The visual acuity test is a common eye exam that measures a person's ability to see fine detail and to distinguish between different shapes and objects. It is used to assess the clarity of vision and to diagnose and monitor visual problems, such as nearsightedness, farsightedness, astigmatism, and age-related macular degeneration.
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Why is the visual acuity test performed?
The visual acuity test is performed to evaluate a person's ability to see clearly at a specific distance. It is used to detect vision problems such as nearsightedness, farsightedness, and astigmatism. The test can also help monitor changes in vision over time and determine the need for corrective lenses or other vision treatments.
.png "The Snellen chart is a visual acuity test")
How is the visual acuity test performed?
The visual acuity test is usually performed using a chart, such as the Snellen chart, which displays rows of letters, numbers, or symbols of different sizes.
The patient stands or sits at a set distance from the chart, and is asked to cover one eye and read the smallest line of letters that can be clearly seen. The same procedure is repeated for the other eye.
The results of the visual acuity test are recorded as a fraction, such as 20/20 or 6/9. The top number of the fraction represents the standard distance at which the test is performed (usually 20 feet or 6 meters), and the bottom number represents the distance at which a person with normal vision can read the smallest line that the patient was able to read.
A visual acuity of 20/20 means that the person can see at 20 feet what a person with normal vision can see at 20 feet, while a visual acuity of 20/40 means that the person can see at 20 feet what a person with normal vision can see at 40 feet.
The visual acuity test is a simple and quick test that can provide valuable information about the health of the eye and the quality of vision. It is usually performed as part of a comprehensive eye examination, along with other tests, such as the eye muscle test and the refraction test, to determine the best corrective lens prescription, if needed.
