Essentials of models of the human eye

It was not until the onset of the Renaissance that ideas would circulate that the retina was the surface over which inverted images were formed. The lines of development that led to this view were well charted by Smith^{1, 2} who describes the philosophies of the ancient Greeks.  

They were of the opinion that the process of vision was enacted by the emission from the eye of a subtle fluid, which interacted with the environment and communicated this information back to the lens in the eye, which in turn transferred this to the optic nerve and, hence, into the brain.