20/13 is excellent vision, as is 20/10. My own vision is corrected to about 20/15. The scale is based on what a normal person with 'perfect' vision can see at 20 FVDI ABRITES Commanders. 20/20 means what a normal person can see at 20 feet, you can see at 20. 20/13 means that what a normal person can see clearly at 13 feet, you can see clearly at 20 feet. Inversely, 20/100 vision means that what a normal person can see clearly at 100 feet, you have to be only 20 feet away to see clearly. So by the books, the three of us have better than 'perfect' vision.