Obviously, if the eye forms part of an optical system, the properties of the eye must be taken into account in assessing the performance of the system, and even in designing it in the first place. The unaided eye is far from being diffraction limited, and it has many other properties which affect the design of any optical system in which the eye is the ultimate image receiver. We shall consider here three particular aspects of the human eye: its di-mensional properties, its photometric properties, and its resolving power.
"Influence Of The Eye On The Performance Of Visual Systems", Proc. SPIE 0039, Applications of Geometrical Optics II, (1 March 1974); doi: 10.1117/12.953775; https://doi.org/10.1117/12.953775