CiViUM scientists have found that if the eye does not suffer the so-called Stiles-Crawford effect we would need more correction to observe nearby objects, due to the interaction with certain eye defects (aberrations). This effect produces that the light entering into the eye near the edge of the pupil is attenuated when reaching the retina.

This behavior is called apodization and in artificial systems, such as telescopes, is used to facilitate the detection of planets near bright stars.
In general, when observing distant objects the eye has positive spherical aberration. However, when the observed objects approach the eye, the change in the shape of the lens produces this aberration to decrease, usually becoming negative. The combination of the apodization with this change in sign produces that we have the best vision with lower correction than in the case the eye does not behave as described by the Stiles-Crawford effect. In this study the mathematical calculations needed to calculate the effect on any optical system affected of spherical aberration and apodization have been developed.