Why light sensors in human eye are located at the back

BBC : Scientists have known for some time that the optical structure in the retina of vertebrates is built backward, with the neurons in front of the photoreceptors rather than behind them. Now Erez Ribak of the Technion–Israel Institute of Technology and colleagues propose one possible explanation. Through the use of in vitro experiments in a mouse model, computer simulations, and three-dimensional scans created with confocal microscopy, the researchers show that the neurons function like optical fibers to funnel red and green light into the eye’s cone cells while allowing blue light to spill over to the rod cells. Red and green light allow humans to see color during the daytime, and blue light allows humans to see in black-and-white under low-light conditions. Thus the eye’s structure is “optimized for our vision purposes,” according to Ribak . The researchers presented their findings at last week’s American Physical Society meeting in San Antonio, Texas.