Figure 8. Differently shaped wave-fronts leaving three types of eye: myopic, hyperopic, and emmetropic. This is simply an alternate view of these common eye aberrations, which are usually explained by drawing paraxial rays from outside to inside the eye. Here we do the contrary: a point light source directed at the retina generates a spherical wave-front which leaves the eye. Because the emmetropic eye is a "perfect" optical system its refractive power is such that a spherical wave-front leaves the eye paraxially, i.e., in the form of a plane wave. The myopic eye has a "stronger" than necessary optical power so light rays leave the eye in converging rays. The opposite happens with the hyperopic eye, which refracts light less than necessary.