Sir Isaac Newton repeatedly did experiments sticking a bodkin (a very sharp needle) between his eyeball and his eye socket, “as neare to backside of my eye as I could”,he was quoted. He did this til he saw spots. He did it because he hoped he might learn something about color.
We all know Sir Isaac Newton was a brilliant mathematician and scientist, but the discoverer of gravity also had flashes of odd behavior. He once stuck a large needle into his eye socket to test his theories about vision, and later in life completely withdrew from his friends, becoming paranoid and confused. It is thought that he may have gone mad after poisoning himself in metal experiments.