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How are optical characteristics influenced by the add power of diffractive multifocal intraocular lenses?

Session Details

Session Title: Multifocal Technology and Comparative studies

Session Date/Time: Tuesday 08/10/2013 | 08:00-10:30

Paper Time: 08:00

Venue: Auditorium (First Floor)

First Author: : M.Langeslag THE NETHERLANDS

Co Author(s): :    H. Weeber   D. Chang M.D.   P. Piers        

Abstract Details

Purpose:

The purpose of this study is to determine how various optical characteristics of diffractive multifocal intraocular lenses (IOLs) are influenced by a change in add power.

Setting:

1) AMO Groningen BV, the Netherlands 2) Empire Eye and Laser Center, Bakersfield, California, USA

Methods:

Various optical properties were determined for three diffractive multifocal IOLs with add powers of 2.75, 3.25 and 4.00 diopter (D). These designs shared the same IOL platform (IOL material, optic, and haptics) and differed only in their diffractive add power. The best focus, through-focus and through-frequency Modulation Transfer Function (MTF) were measured on an optical bench in an eye model that reproduces the spherical and chromatic aberration of an average pseudophakic eye. Testing was done using aperture sizes varying between 2 and 5 mm, and for green and white light. Additionally, stray light at visual angles between 0.6 and 2 degrees was measured, and simulated halo images were composed. Finally, using computer-based model eyes, defocus curves were simulated both for visual acuity and contrast sensitivity. By comparing all results and performing a theoretical evaluation, the optical outcomes were correlated with add power. Additionally, the results were compared to other multifocal IOLs designed to improve intermediate vision.

Results:

The MTF values in white light for a 3 mm pupil were measured to be between 0.25 and 0.30 for all models for both near and far focus. For all test conditions, MTF in far and near focus was independent of add power. Only the distance between the near and far focus peak differed, corresponding to the add power differences. As add power is reduced, the peaks of the maximum stray light are also reduced and move closer to the optical axis. Halo images and stray light results show that lower add powers produce proportionally smaller halos. Except for the distances between the near and far focus peaks, simulated contrast vision and visual acuity curves show little or no change in the in-focus behavior between IOLs with different add powers. However, with lower add powers, simulated intermediate vision improves. The same trends are found for the other multifocal IOLs tested.

Conclusions:

Lowering the add power of diffractive multifocal IOLs has no effect on in-focus near and far vision. The results show the location of the near vision changing from a to-be-expected in vivo distance of 33 cm for the 4.00 D add to 50 cm for the 2.75 D add. Based on in vitro measurements, a difference in the size and intensity of halo as well as an improved intermediate vision may be expected when add power is reduced.

Financial Interest:

... is employed by a for-monetary company with an interest in the subject of the presentation, ... travel has been funded, fully or partially, by a company producing, developing or supplying the product or procedure presented, ... research is funded, fully or partially, by a company producing, developing or supplying the product or procedure presented, ... receives consulting fees, retainer, or contract payments from a company producing, developing or supplying the product or procedure presented