20/20 doesn’t refer to two eyes. It means you can see what you should see at 20 feet. 20/40 means you see at 20 feet what you should be able to see at 40 feet.
20/20 doesn’t refer to two eyes. It means you can see what you should see at 20 feet. 20/40 means you see at 20 feet what you should be able to see at 40 feet.