500
In his book, The Book of Optics, he was the first to disprove the ancient Greek idea that light comes out of the eye, bounces off objects, and comes back to the eye. He delved further into the way the eye itself works. Using dissections and the knowledge of previous scholars, he was able to begin to explain how light enters the eye, is focused, and is projected to the back of the eye.
Who is Ibn Al-Haitham?