40/40 would be the same as 20/20 or 10/10

40/40 is being able to make out a letter at 40 feet that a person with good vision can make out at 40 feet. so 20/200 is a person that can make out a character at only 20 feet while a normal person can make it out at 200.

I think you're looking for 20/10 which would be better than average vision.