Funnel vision: Waveguides in your retina

The light-sensitive rods and the color-perceiving cones are at the back (posterior to the pupil) of the 10-layer retina. Why is all that junk in front of the sensors? New research indicates that the intervening layers contain glial cells (called Müller fibers), like the white matter in your brain, which act as waveguides to improve photoreceptor efficiency.