I don't know what unit is used in the USA but in France, as well as other European countries, requirement is for:
* 10/10 to both eyes although down to 6/10 is permitted by the time you recover 10/10 with glasses.
* No color blindness
Actually, when you're taking your medical, there's a whole set of different vision tests (colors, relief, exophoria...)
The sky has no limit...