Understanding the role of retinal cone photoreceptors in color perception, blur, and emmetropization

The photoreceptors are responsible for the conversion of optical images into neural signals that are conveyed to the visual cortex where vision is triggered. Rod photoreceptors provide night vision whereas cone photoreceptors provide daylight vision and color perception. The photoreceptors have commonly been represented as discrete but dense array of pixels despite of their elongated cellular structure. Earlier studies have suggested that they act as biological waveguides transmitting images from the inner to the outer segments. However, this understanding may not fully encompass their role in vision which is more related to that of optical antennas organized in such a way that optical image contrast and resolution is optimized. Here, we discuss the role of the photoreceptors analyzed as three-dimensional adaptable detectors of light (voxels) using electromagnetic principles. We show that this understanding is compatible with how light is perceived when being incident onto the retina at different angles in the effect commonly known as the StilesCrawford effect. We discuss how this can explain the reduced sensitivity to aberrations and chromatic blur of the threedimensional retina when compared to the common two-dimensional understanding of image formation in the eye. We show how the same principles may impact on emmetropization and ultimately how it may play a key role to prevent the
onset or progression of myopia.