Warning - Do not try this at home.

From A Short History of Nearly Everything by Bill Bryson:
“[Isac Newton] built his own laboratory, the first at Cambridge, but then engaged in the most bizarre experiments. Once he inserted a bodkin - a long needle of the sort used for sewing leather - into his eye socket and rubbed it around ‘betwixt my eye and the bone as near to [the] backside of my eye as I could’ just to see what would happen. What happened, miraculously, was nothing - at least, nothing lasting. On another occasion, the stared at the Sun for as long as he could bear, to determine what effect it would have upon his vision. Again he escaped lasting damage, though he had to spend some days in a darkened room before his eyes forgave him.”