This paper describes some aspects of the human eye adopting a progressive approach. We begin studying a simple visual system to which we progressively include the other eye components. Initially, the human eye is represented by a simple void sphere with a hole through which the light passes and strikes the opposite surface where is the retina. However, this simple model does not produce a sharp image on the retina. In order to improve the image quality, the sphere is filled with a material with a refractive index equal to that of the substances that fill the eye (vitreous and aqueous humors). The image formed in the retina becomes less blurred, but not completely sharp. After that, we study the role of the cornea to the improvement of the image quality. But the cornea does not ensure a perfect image. The next step is to study the role of the lens. The adopted approach is more or less similar to the evolutionary history of the eye during the last 500 million years, from a simple photosensitive sheet to the complex vertebrate eyes. Calculations are performed using the basic equations of the geometric optics. Finally, we present a model of the human eye made with transparent spheres which allows us to explore some aspects of the human vision.
optics; human eye; vision
