This is perhaps a poor backup claim because I can't give a relevant citation, but back when I was in Neuroscience / neuroanatomy in medical school, I remember feeling deeply impressed at the level to which we do understand the visual processing system in the brain. Its far more comprehensive than simple imaging studies -- we know where the wires go, how the photons are transduced and turned into patterns of neurons firing, etc. There's of course plenty to learn but our depth of understanding in regards to human vision is impressive.