How are eye vision test generally scored?

Eye chart. Vision is recorded by the smallest line read on the vision chart in reference to 20/20 being normal, and it is recorded with and without your best correction.
Compared to standard. The chart used to test the eye is calibrated for normal vision at 20 feet. The outcome achieved is compared to what a normal eye can see at 20 feet. So if you can only see at 20 feet what a normal eye sees at 40 feet, your vision is considered to be 20/40. This is measured with and without corrective lenses at distance and at near. The vision with correction is considered to show the true vision.