THE QUALITY OF EYESIGHT BETWEEN THEORY AND PRACTICE

The technological evolution allowed the standardization of cataract surgery from a practical point of view. The replacement of the affected eye lens is followed by implanting a foldable artificial eye lens which refractively restores the ocular diopter. The current challenge is the best quality of eyesight. The eyesight is a complex process in which the perception of visual stimulations is determined by numerous factors: anatomical, optical, neurological perception and processing. There is also a great variety of adjusting mechanisms that compensate the errors which may occur in the optic system (the Stiles-Crawford effect). The only factor that a cataract surgery can have an impact on is the optical factor. The main causes for optical quality decrease of a system are diffraction, aberrations and dispersion. These three phenomena cause an image of a dot to produce a diffuse circle on the retina. 90 % are low order aberrations (canting, defocusing, astigmatism) that are usually eliminated through a biometry and a thorough surgical technique. There are also high order aberrations, though, that affect the quality of eyesight, such as spherical aberration and coma