The optics of the eye imposes the upper bound on the image details that can be seen by the visual system. It is important to understand and be able to model this limit of image quality under various viewing conditions, so that the performance by imaging systems can be properly optimized. However, it should be pointed out that the optical characteristics of the human eye are constantly changing throughout life, and there are also very significant variations among individuals. In this chapter, we will first describe the important features of the anatomy of the eye. Since the anatomy shows a structure too complicated to model in detail, we will then describe two simplified optical models of the eye: the reduced eye and the schematic eye. These models are very useful because they allow us to make good estimates of geometrical metrics for our retinal images. We will discuss some optical properties of the ocular media and the eye as awhole. We will also touch on the mechanism of accommodation and pupil control. Finally, we will describe how to put together a computational model of the eye optics for calculating the optical quality of the retinal image. Such a model will allow us to performmore detailed analyses under various viewing conditions and for different stimuli.

Before our discussion on visual optics, we need to define “visual angle” as a measure of image size and retinal distance. Since the image size of an object on the retina depends on its distance from the eye, it is often more convenient to use visual angle to specify object size or retinal distance.