Background: A method is developed to demonstrate how implanted diffractive multifocal IOLs process
the light they receive from the cornea.
Methods: Monochromatic green light is projected through a model eye with a physiological cornea
in front of the IOL. The converging bundle of light leaving the IOL is visualized.
Also a US-Airforce target is projected through the model eye. The projected (retinal)image
is captured with a CCD camera. The IOL's tested are the TECNIS ZM001 diffractive multifocal
lens; a refractive multifocal lens (Array SA40N); a spherical diffractive multifocal
lens (CeeOn 811E) and 2 monofocal lenses.
Results: The converging light bundle of a diffractive lens mainly consists of 2 different
light bundles, that are refracted/diffracted to 2 focal points independent of pupil
size. The light bundle coming from a refractive multifocal lens consists of a number
of small bundles coming from different refracting zones, that are refracted to 2 main
focal points. At 5mm pupil size the projected US-Airforce target shows the best image
quality for the TECNIS ZM001 lens. The quality of both far and near image of this
lens is better than the image quality of a monofocal spherical IOL.
Conclusions: The functional difference of diffractive and refractive multifocal lenses is demonstrated
in a physiological model eye by visualizing the light bundle after passing the IOL.
Also an impression could be given of the difference in quality of the projected retinal
images.
