For the first time, researcher have confirmed that the human retina is built backwards, with the neurons in front of the photoreceptors, rather than behind them.
“The retina is not just the simple detector and neural image processor as believed until today. Its optical structure is optimised for our vision purposes,” explained Erez Ribak, professor at the Technion – Israel Institute of Technology.
From a practical standpoint, the wiring of the human eye – a product of our evolutionary baggage – does not make a lot of sense. In vertebrates, photoreceptors are located behind the neurons in the back of the eye – resulting in light scattering by the nervous fibres and blurring of our vision.
“New research has confirmed the biological purpose for this seemingly counter-intuitive setup,” Ribak added.
Ribak’s interest in the optical structure of the retina stems from his previous work applying astrophysics and astronomy techniques to improve the ability of scientists and ophthalmologists to view the retina at high detail.
Previous experiments with mice suggested that Muller glia cells, a type of metabolic cell that crosses the retina, play an essential role in guiding and focusing light scattered throughout the retina.
To test this, Ribak and his colleagues ran computer simulations and lab experiments in a mouse model to determine whether colours would be concentrated in these metabolic cells.
They used confocal microscopy to produce 3-D views of the retinal tissue and found that the cells were indeed concentrating light into the photoreceptors. The team is now planning to use water-filled goggles to reduce corneal aberrations, allowing observers to gain a finer view of the retina at depth.
Ribak and study co-authors are set to describe their work during the 2015 American Physical Society meeting in San Antonio, Texas, March 5.