Light-sensitive cells active in the retina even before the fetus can distinguish images may play a larger role in the developing eye and brain than previously thought. Intrinsically photosensitive retinal ganglion cells seemingly help establish blood supply to the retina, circadian rhythms and the pupillary light reflex. Researchers have now discovered that these cells are electrically connected in a network that is able to detect light intensity, suggesting a bigger role in development.