Müller cells separate between wavelengths to improve day vision with minimal effect upon night vision
Amichai M. Labin, Shadi K. Safuri, Erez N. Ribak & Ido Perlman
Nature Communications volume 5, Article number: 4319 (2014)
Abstract
Vision starts with the absorption of light by the retinal photoreceptors—cones and rods. However, due to the ‘inverted’ structure of the retina, the incident light must propagate through reflecting and scattering cellular layers before reaching the photoreceptors. It has been recently suggested that Müller cells function as optical fibres in the retina, transferring light illuminating the retinal surface onto the cone photoreceptors. Here we show that Müller cells are wavelength-dependent wave-guides, concentrating the green-red part of the visible spectrum onto cones and allowing the blue-purple part to leak onto nearby rods. This phenomenon is observed in the isolated retina and explained by a computational model, for the guinea pig and the human parafoveal retina. Therefore, light propagation by Müller cells through the retina can be considered as an integral part of the first step in the visual process, increasing photon absorption by cones while minimally affecting rod-mediated vision.
FREE PDF GRATIS: Nature Communications Sup. Info.
+++++
Having the photoreceptors at the back of the retina is not a design constraint, it is a design feature. The idea that the vertebrate eye, like a traditional front-illuminated camera, might have been improved somehow if it had only been able to orient its wiring behind the photoreceptor layer, like a cephalopod, is folly.
Ter os fotorreceptores na parte posterior da retina não é uma limitação de design, é uma característica de design. A ideia de que o olho dos vertebrados, como uma câmera tradicional com iluminação frontal, poderia ter sido melhorada de alguma forma se tivesse sido capaz de orientar sua fiação atrás da camada fotorreceptora, como um cefalópode, é bobagem.
