Online Eye Test

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Welcome to the Snellen online eye test.  This eye test is quick and simple, designed to help you determine your visual acuity.

The Snellen eye chart was developed by Dr. Hermann Snellen in 1862 and has been used by optometrists for years to measure the strength of a person’s vision. The top number in the Snellen fraction is always 20. It refers to the standardized visual acuity testing distance of 20 feet. The bottom number of the fraction describes the farthest distance from which a person with normal eyesight can recognize the smallest letters you can see when you are 20 feet from the chart. Therefore, "20/20" means that you can see at 20 feet what the average person can see at 20 feet.

When you are ready to do the test, click on image to enlarge.

How to Use the Online Eye Test

1) You will need a ruler or a tape measure.
2) At the top of the chart is a blue “standardization bar.” Use your ruler/ tape measure to measure the length of the blue bar in centimeters on your computer screen.
3) Whatever this number is, stand back from the computer so that your eye is that number of feet away. For example, if the blue bar is 9 centimeters long then stand back so that your eye is 9 feet away from the screen.
4) If you normally wear glasses for distance wear, put them on.
5) Test your right eye by covering your left eye with your hand, and read out the letters starting from the top line.
6) There are six lines in total. Make a note of the last line in which you can read most (50-75%) of the letters.
7) Test your left eye by covering your right eye with your hand, and read out the letters starting from the top line and make a note of the last line in which you can read most (50-75%) of the letters.

How to Understand Your Results

1) The middle letter of the top line is equivalent to 20/200. A person who is unable to read this letter with the best eyeglass correction is considered legally blind.
2) The “T” and “B” on the top line is equivalent to 20/100. If you can only read most of the letters up to the second line, then you are considered to have 20/50 vision.
3) The third line is equivalent to 20/40. In obtaining a drivers license you are normally required to have at least 20/40 vision.
4) The fourth line is equivalent to 20/30, the fifth line is equivalent to 20/20 and the bottom line is equivalent to 20/10. These are considered to be “normal vision".

This vision test can only be used as a screening test. Many factors including lighting, glare and the quality of your computer monitor may have an effect on the results of the test. For an accurate eye test, please visit your Optometrist.