What A Vision Test Involves?
A Vision Test is probably one of the simplest parts of an eye examination. This eye vision test is however the most important part. The eye vision test is done at a distance of twenty feet which is that standard distance. The charts used for an eye test are also standard and worldwide the same basic format is used.
The Basic Eye Test
The basic eye vision test involves the use of a standard chart that the patient must read from. Each line of the chart used for an eye vision test represents a fraction that evaluates your vision acuity. The numerator of the fraction is the distance in feet that the patient is from the eye chart whilst the denominator of the fraction represents the distance an eye with normal vision can read this line.
The Color Vision Test
A color vision test is used to asses a patients color efficiency or deficiency. The color vision test uses a number of different plates to test your eyes for color deficiencies. In simple terms, a color vision test is used to check a patient’s ability to distinguish between different colors. This color vision test is also called the Ishihara color vision test.
This eye vision test is performed in a comfortable seating position. You will be shown a number of symbols that are made up of colored dot patterns. The background of the dotted patterns will be randomly mixed colors. During the color vision test you will be asked to identify if you can what symbol is on the card.
The color vision test is carried out on each eye and the tester will hold the plates used approximately 14 inches from your face. You will be asked to identify each symbol as quickly as possible.
This color vision test is very similar to an eye vision test in that both eyes are tested separately. By using the different plates in a color vision test the tester is able to evaluate the function of the optic nerve. Changes in color vision can often indicate the first signs of a vision problem.
If you have a normal color vision test, you will be able to distinguish all the symbols. An abnormal color vision test can have 4 different results.
Deuteranopia is difficulty distinguishing between red/purple and green/purple.
Tritanopia is a difficulty distinguishing between yellow/green and blue/green.
Achromatopsia is complete color blindness in which you will only see shades of gray.
If you are in any way worried about your color vision, there are a number of websites where you can take an online vision test.
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