ABSTRACT
The final image in a visual instrument is formed at the retina of a human eye. If the eye is emmetropic, that is, if it does not have any refractive errors, the virtual image provided by the instrument has to be located at an infinite distance. Another consideration that should be made regarding the exit pupil in visual instruments is its optimum location with respect to the observing eye. When numerically tracing rays in a computer to analyze the off-axis performance of a visual system to which this model of the eye has been attached, the eye model has to be rotated about the center of the exit pupil of the system being analyzed. An alternative to avoid rotating the eye model for each off-axis point is to use as an eye model a system that produces good quality optical images on-axis as well as off-axis.
