The retina has long been known to convert light into electrical signals and initially process visual information, but that’s not all it does. Researchers from Technion Israel Institute of Technology have demonstrated the role that glial cells inside the retina (also known as Müller cells) play in the improvement of vision. Light, arriving from above, is guided toward the photoreceptors (blue layer at the bottom) by glial (Müller) cells acting as optical fibers. Courtesy of Technion Israel Institute of Technology. Vision starts with the absorption of light by retinal photoreceptors — the well-known cones and rods. Due to the retina’s inverted structure, however, incident light must propagate through reflecting and scattering cellular layers before reaching those photoreceptors. In their study, the researchers viewed how light passes through the eye to fall directly onto the retina. This light is then separated into colors by the funnel-shaped Müller cells, which function as wavelength-dependent optical fibers spanning the retinal depth. Red-green light is guided to photoreceptor cones, the light detectors responsible for daytime color vision, while blue-violet colors are scattered to the surrounding rod photoreceptors, which are more active at night. According to the researchers, such separation of colors can improve a subject’s daytime peripheral vision up to 10 times without impairing his or her night vision. The light guiding and color-sorting processes explain why the vertebrate retina has a seemingly inverted structure, with photoreceptors set behind layers of neural cells and cell nuclei, rather than in front of them, the researchers said. The research was published in Nature Communications (doi: 10.1038/ncomms5319). For more information, visit www.technion.ac.il.