How Glasses Have Been Used To Correct Visual Problems
Unbelievably, in the old days, a person’s reading eyeglasses’ strength was only a function of that person’s age. Hence a man of about 30 would be given lenses with 2 degrees of strength and a person of about 70, given, roughly, 4 degrees. It wasn’t until the middle of the 19th century that eyeglasses started [...]