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Assessing the defocus tolerance of intraocular lenses: method based on the through-focus MTF curves

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Session Details

Session Title: Presented Poster Session: Pseudophakic IOLs

Session Date/Time: Tuesday 08/09/2015 | 09:30-11:00

Paper Time: 10:50

Venue: Poster Village: Pod 3

First Author: : A.Del Ɓguila-Carrasco SPAIN

Co Author(s): :    J. Esteve-Taboada   E. Papadatou   T. Ferrer-Blasco   R. Montes-Mico     

Abstract Details

Purpose:

To present a new metric to quantify the defocus tolerance of intraocular lenses (IOLs) by means of the through-focus modulation transfer function (MTF).

Setting:

University of Valencia, Spain

Methods:

The Full Width at Half Maximum (FWHM) is widely used in phenomena such as the duration of pulse waveforms. As its name indicates, this expression calculates the width of a peak in a function at half of its height. This is interesting for analyzing through-focus curves of, for instance, IOLs. Particularly, its utility increases when analyzing multifocal IOLs, which will present several peaks in the through-focus curve. FWHM was calculated for a bifocal IOL with 20 D of nominal power and an addition of 3.75 D at different spatial frequencies ranging from 20 to 120 cycles/mm.

Results:

Defocus tolerance for both the far vision and near vision foci was analyzed using the FWHM. In general lines, the bifocal lens presented a slightly larger defocus tolerance for the near vision than for the far vision. At some spatial frequency values the FWHM was equal for both foci (between 80 and 85 cycles/mm and between 110 to 120 cycles/mm). The variations in the FWHM for both foci with respect to the spatial frequency were fitted to a power function, resulting in a coefficient of determination greater than 0.99 in both cases.

Conclusions:

A fast and easy method to quantify the defocus tolerance of optical systems has been presented. This method seems particularly interesting for multifocal IOLs, since the through-focus curves at different spatial frequencies present several peaks that can be analyzed using this method. Hence, defocus tolerance for each peak of multifocal IOL can be rapidly characterized.

Financial Interest:

NONE

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