Distance from the eye chart are used to find defect in the in the eye sights of a patient. If one cannot see far off things, that means he is near sighted. So if he goes away from the eye chart and try to see the letters in the chart, he will see blur image of the letters.
And if one is far sighted he cannot see the near by things. If one comes closer to the chart and tries to read the letters then he will not be able to read those letters because he is far sighted.
Thus, in this way distance from the eye chart affect to recognize the letters present in the eye chart.
Well, if you are nearsighted which means you can't see far, the father you are the more blurry it will be, resulting to you saying the wrong letter. This then shows the doctor that you can't see far away, nearsighted.
