You don’t. You just need dark skies. Careful observers with good eyes see much more than 7. It's also worth mentioning that, as I alluded to in another comment

You don’t. You just need dark skies. Careful observers with good eyes see much more than 7. It's also worth mentioning that, as I alluded to in another comment, myopia is much more common than it was pre-industrially, and it's still rising to what opthamalogists say is "epidemic" proportions. Good eyesight was much more common then.