Problems in the measurement of wavefront aberration for eyes implanted with diffractive bifocal and multifocal intraocular lenses.

Purpose: To determine the origin of the wavefront aberration as measured in eyes fitted with diffractive intraocular lenses (IOLs).
Methods: Wavefront aberration was measured by Shack-Hartmann aberrometry in 2 eyes fitted with diffractive bifocal contact lenses and 10 eyes implanted with Acrysof ReSTOR multifocal IOLs.
Results: Problems were encountered as a result of the multiple wavefronts generated by the diffractive lenses and their dependence on wavelength. These led to ambiguities in the positions of the Shack-Hartmann spot images and in the form of the derived wavefronts.
Conclusions: Aberrometry may not provide reliable information on the wavefront aberration associated with either the distance or near power of diffractive IOLs.