In 1728 English surgeon William Cheselden removed the cataracts from a 13-year-old boy, producing the first known case of full recovery from blindness:

Having often forgot which was the cat, and which the dog, he was ashamed to ask; but catching the cat, which he knew by feeling, he was observed to look at her steadfastly and then, setting her down said, ‘So, puss, I shall know you another time.’ He was very much surprised, that those things which he had liked best, did not appear most agreeable to his eyes, expecting those persons would appear to be most beautiful that he loved most, and such things to be most agreeable to his sight, that were so to his taste.

Also: “Being shewn his father’s picture in a locket at his mother’s watch, and told what it was, he acknowledged the likeness, but was vastly surprised; asking, how it could be, that a large face could be expressed in so little room, saying, it should have seemed as impossible for him, as to put a bushel of anything into a pint.” A fuller account is here. See also Molyneaux’s Problem.