In order to limit measurement errors, it is preferable to carry out this test on a blank A4 sheet of paper, and not on a computer, tablet or smartphone, which can distort the size of the characters.

By placing the test 35 cm from your face, equivalent to the average length of a forearm, you will be able to perform the diopter test optimally.

Of course, be sure to remove any vision devices such as glasses or lenses to get a fair measure of the correction your eyes need.

Once you are comfortable, perform the diopter test by reading each line from top to bottom. If you can't read a line, refer to the number to the left of the line: This is the correction you need.