In vitro evaluation of a novel extended depth of field intra-ocular lens design

Abstract

Purpose : Multifocal vision correction devices commonly suffer from diminished performance for intermediate viewing distances. Recent advances in certain optical design approaches^1,2 have provided extended depth of field (EDOF) performance with the potential to maintain consistent visual performance over a wide range of near object vergences. We evaluated the theoretical and in vitro optical performance of a novel optical approach for achieving EDOF³.

Methods : IOL designs were developed by optimisation of the EDOF features in the Arizona eye model (AEM)⁴ using Zemax. The EDOF performance of the novel design was evaluated by computing the through-field (TF-) point spread function (PSF) in the AEM over the object vergence range of -3 D to +3 D in 0.1 D steps.
PMMA IOLs were fabricated according to the above designs and tested on a physical model eye⁵ with a modified anterior chamber fixture for positioning the IOL.
Both TF-PSF and TF-equivalent visual acuity were evaluated over the same object vergence range as the Zemax computation (4 mm entrance pupil diameter and polychromatic photopic illumination).
The performance of a single-vision IOL design, with the same base design geometry but without the EDOF features, was also evaluated for comparison.

Results : Theoretical and physical results for TF-PSF were comparable. The EDOF-IOLs exhibited EDOF from distance to more than 2 D with a high PSF peak at distance coupled with a continuous PSF amplitude from intermediate to near. In comparison, the SV-IOL exhibited approximately 1 D depth of field for a 4 mm pupil albeit with a higher PSF peak. Comparative TF-PSF plots for the SV and EDOF-IOL designs are shown below.

Conclusions : While in-eye results will be required for clinical validation of EDOF performance, the results demonstrate the potential of PS optics as an additive technology for providing EDOF to an ophthalmic device.

References
1. Torun et al (2016) BMC Ophthalmology
2. Tilia et al (2017) J Optom
3. Zlotnik et al (2009) Optics Letters
4. Schwiegerling J (2004) SPIE FG04
5. Bakaraju et al (2010) Opt Express

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.

 

TF-PSF measured on a physical model eye of an EDOF-IOL (right) and a SV-IOL (left) with the same lens base geometry.