The human eye can distinguish about ten million colours thanks to the light-sensitive lining at the back of our eye. Containing millions of cells, called rods and cones, the retina (pictured flattened out from a mouse eye) absorbs light and transmits this visual information to the brain. Also within this specialised layer are thousands of melanopsin retinal ganglion cells (stained purple) that control our subconscious responses to light, such as the shrinking and expanding of our pupils. Scientists reveal that these cells also provide unexpected amounts of visual information to the brain during conscious vision. In mice completely lacking rods and cones, the contribution of these ganglion cells was enough to prompt responses to light. This discovery may help to solve the mystery of why some people who lose rods and cones as a result of eye disease can still consciously detect the presence of light even when blind.
Written by Lux Fatimathas
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