PURPOSE: To study the impact of loss in optical quality from glistenings in diffractive multifocal intraocular lenses (IOLs) using ray tracing in a model eye.
SETTING: Independent research laboratory, Irvine, California, USA.
DESIGN: Experimental study.
METHODS: A pseudophakic eye model was constructed in Zemax, an optical ray-tracing program, using the Arizona eye model as the basis. The Mie scattering theory was used to describe the intensity and direction of light as it scattered for a spherical particle immersed in a diffractive multifocal IOL. To evaluate the impact of glistening scatter, a more advanced eye model was constructed in Fred, a nonsequential optical ray-tracing software. An evaluation of scatter and modulation transfer function (MTF) was performed for a hydrophobic biomaterial with a refractive index of 1.54 for various sizes and densities of glistenings under mesopic conditions.
RESULTS: As predicted by the Mie theory, the amount of scatter was a function of the change in the refractive index, size of the scatterer, and volume fraction of the scatterers. This modeling showed that an increase in density of glistenings can lead to a significant drop of MTF of the IOL. This effect was more pronounced in multifocal IOLs than in monofocal IOLs.
CONCLUSIONS: Mathematical modeling showed that glistenings in multifocal IOLs lead to a reduction in MTF of the IOL and the pseudophakic eye. The relative loss of MTF in multifocal IOLs was more significant than in monofocal IOLs because of the nature of the design.
FINANCIAL DISCLOSURE: Drs. DeHoog and Doraiswamy are consultants to Advanced Vision Science, Inc.
Copyright © 2016 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.
- From Optical Engineering & Analysis LLC (DeHoog), Irvine, and Independent Consultant (Doraiswamy), San Francisco, California, USA.