In some scenes, the glow in the pupils of replicants' eyes creates a sense of artificiality. This effect was produced by cinematographer Jordan Cronenweth shining a light along the optical axis of the camera. According to Ridley Scott, "that kickback you saw from the replicants' retinas was a bit of a design flaw. I was also trying to say that the eye is really the most important organ in the human body. It's like a two-way mirror; the eye doesn't only see a lot, the eye gives away a lot. A glowing human retina seemed one way of stating that". Scott considers the glow to be a stylistic device (non-diegetic); only visible to the viewers to help them understand that they are viewing a replicant, almost always occurring after the characters have assumed as much.