What is the end-point determinant for spatial resolution: Photoreceptor diameter or contrast sensitivity?

Spatial resolution of the eye is determined in the complex pattern and all the layers of the retina as well as the primary visual cortex and lateral geniculate body contribute. There is evidence that any given pathway transmitting visual information is restricted to a limited band of spatial frequencies. Moreover, it seems that the limiting array is in the retina. More than a century ago, Bergmann and Helmholtz laid the foundation for the sampling theory of visual resolution when they argued that for two points to be discriminated, at least one unstimulated photoreceptor must lie between two stimulated photoreceptors. In this article, we propose that the photoreceptor diameter is not the limiting factor for spatial resolution, and contrast sensitivity is the end-point determinant factor in the spatial frequencies less than photoreceptor diameter.