Abstract
Purpose: :
We measured three types of IOLs using a two-wavelength Shack-Hartmann wavefront aberrometer (SHWA) and modulation transfer function (MTF) equipment and investigated the validity of a wavefront aberration (WA) measurement of multifocal IOLs.
Methods: :
A monofocal IOL (Sensar AR40e AMO), a refractive multifocal IOL (ReZoom NXG1 AMO), and an apodized diffractive multifocal IOL (AcrySof Restor SA60D3 Alcon) were measured. We developed an aberration-free artificial eye (AFAE) which could hold an IOL to measure its aberration and MTF in the water. Wavefront sensing (WS) was performed on the AFAE with each IOL using a two-wavelength (561nm and 840nm) SHWA. Through focus MTF (TF-MTF) of the AFAE with the IOLs were also measured using a TF-MTF measurement system (MATRIX PLUS Nanotex corp.) in visible and near infrared (NIR) wavelengths.
Results: :
RMS of the WAs of the AR40e was 0.01µm for the 4-mm circle area and 0.06µm for the 6-mm circular area. Spatial pattern of Hartmann image of the NXG1 was distorted and the distortion was rotationally symmetrical because the IOL had five annular power zones. TF-MTF calculated from the WAs had peaks at two defocus positions. PSFs in the Hartmann image of the AFAE with SA60D3 were blurred a little with 840-nm WS but some PSFs were split into two spots with 561-nm WS. We could calculate distant or near refraction selecting one of those split PSFs. TF-MTF of the AR40e had a peak only at one focus position, but that of NXG1 had peaks at two defocus positions in both wavelengths. TF-MTF of the SA60D3 had peaks at two defocus positions in 561nm, but one peak in 840nm.
Conclusions: :
We could evaluate multifocality of the diffractive multifocal IOL using the visible wavelength. We also confirmed that wavefront sensing of a diffractive multifocal IOL with an infrared wavelength is valid to measure distance vision.
Keywords: intraocular lens • aberrations • optical properties