Proceedings Article | 3 November 2011
KEYWORDS: Eye, Eye models, Cornea, Aspheric lenses, Spherical lenses, Surgery, Monochromatic aberrations, Crystals, Information operations, Optical design
As a result of modern technological advances, cataract surgery can be seen as not only a rehabilitative operation, but a
customized procedure to compensate for important sources of image degradation in the visual system of a patient, such
as defocus and some aberrations. With the development of new materials, instruments and surgical techniques in
ophthalmology, great progress has been achieved in the imaging capability of a pseudophakic eye implanted with an
intraocular lens (IOL). From the very beginning, optical design has played an essential role in this progress. New IOL
designs need, on the one hand, theoretical eye models able to predict optical imaging performance and on the other hand,
testing methods, verification through in vitro and in vivo measurements, and clinical validation. The implant of an IOL
requires a precise biometry of the eye, a prior calculation from physiological data, and an accurate position inside the
eye. Otherwise, the effects of IOL calculation errors or misplacements degrade the image very quickly. The
incorporation of wavefront aberrometry into clinical ophthalmology practice has motivated new designs of IOLs to
compensate for high order aberrations in some extent. Thus, for instance, IOLs with an aspheric design have the potential
to improve optical performance and contrast sensitivity by reducing the positive spherical aberration of human cornea.
Monofocal IOLs cause a complete loss of accommodation that requires further correction for either distance or near
vision. Multifocal IOLs address this limitation using the principle of simultaneous vision. Some multifocal IOLs include
a diffractive zone that covers the aperture in part or totally. Reduced image contrast and undesired visual phenomena,
such as halos and glare, have been associated to the performance of multifocal IOLs. Based on a different principle,
accommodating IOLs rely on the effort of the ciliary body to increase the effective power of the optical system of the eye
in near vision. Finally, we present a theoretical approach that considers the modification of less conventional ocular
parameters to compensate for possible refractive errors after the IOL implant.
