Optical analysis of different types of intraocular lenses. "Real life" measurements of Dioptric Power, Spherical Aberration and Strehl Ratio

Abstract

Purpose : To determine the optical quality and magnitude of high order aberration (HOA) of three commercial available intraocular lenses (IOL) with three different dioptric power.

Methods : Three different IOL designs were analyzed. A spherical and two aspheric lenses were chosen. (Alcon SN60AT®, Bausch and Lomb MX-60® and AMO Tecnis ZCB00®). IOL power analyzed were 15D, 20D and 25D and two IOLs of each power was used resulting in a N=18. These IOLs were tested in an optical circuit with a Hartman-Shack wavefront sensor. Reconstruction of the wavefront error was done using Zernike polynomials limiting to 44 terms and mean Defocus, Spherical Aberration (SA) and the Strehl-Ratio (SR) were recorded for analysis. Aberration magnitudes were calculated using the following formula.
Where,
S_ab-IOL = Sagita of the calculated aberration in µm.
C^m_n = Zernike aberration coeficient.
�� = wavelength.
n_IOL = IOL index of refraction.
D_L = IOL diameter in mm.
D_C = Decomposion diameter in mm.
D_M = Relay’s 2nd lens focal distance in mm.
D_F = Relay’s 1st lens focal distance in mm.

Results : Mean defocus was calculated for each IOL model and dioptric power and was as follow. 15D IOL was 14.967D for the SN60AT model, 15.021 for the MX-60 and 15.091 for the ZCB00. For the 20D lens defocus was 20.172D for the SN60AT model, 19.902D for the MX-60 and 20.122D for the ZCB00. For the 25D IOL, defocus was 24.880D for the SN60AT, 25.201D for the MX-60 and 25.014 for the ZCB00. SA was 0.830µm, 0.021µm and -0.212µm for the 15D IOLs, 1.201µm, 0.114µm and -0.113µm for the 20D lens and 1.630µm, -0.099µm and -0.310µm for the 25D respectively for the SN60AT, MX-60 and ZCB00. SR was 0.301, 0.442 and 0.438 for the 15D IOLs, 0.297, 0.318 and 0.310 for the 20D lens and 0.280, 0.301 and 0.303 for the 25D IOL respectively for the SN60AT, MX-60 and ZCB00.

Conclusions : All IOLs tested were within manufacturing range conformity. SR comparison showed that spherical IOLs have lower optical quality than aspheric ones, however, clinical correlation was not addressed in this study. SA measured differed from the values informed from manufacturers and this difference should be considered when choosing a specific lens for the patient.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.