1. On the evaluation of multifocal IOLs by means of a vision simulator
Anna Giner, Mikel Aldaba, Montserrat Arjona, Jaume Pujol
CD6: Centre for Sensors, Instruments and Systems development – Universitat Politècnica de Catalunya (Barcelona Tech), Terrassa, Barcelona, Spain.
INTRODUCTION
Multifocal Intraocular Lenses (MIOLs) are one of the possible solutions to solve presbyopia and cataracts at the same time. Attributable to the several foci and the IOL design, MIOLs show certain disadvantages as the adaptation, contrast sensitivity reduction and halos. A new instrument designed for vision emulation through IOL Lenses (VirtIOL, 101Lens S.L.U) has been recently developed to predict the performance of the IOLs before implantation. The main goal of the present study has been to evaluate the performance of a new design and a commercial multifocal intraocular lens by means of the VirtIOL vision simulator.
MATERIAL AND METHODS
VirtIOL vision simulator: is an instrument based on projecting an IOL onto the patients’ pupil plane (Figure 1). There is no magnification effect and the refraction is compensated for far vision.
IOLs: three MIOLs and one monofocal IOL were tested in this study (Table 1).
Patient and operator: all the measurements were performed by the same operator and the same well trained observer, who is a male 54 years old. All measurements were performed with his left eye. VT ME
IOL L M E D P C
IOL
Manufacturer
Power
Addition
NDIO L –CN (MIOL)
OPHTEC
+20.00D
+2.75D
NDIOL – CF (MIOL)
MPlus (MIOL)
Oculentis
+3.00D
Artisan Aphakia (Monofocal IOL) -
Table 1: Technical specifications of the IOLs.
Protocol: All the following tests were performed 3 times for each lens.
Visual Acuity (VA) was evaluated by means of a through-focus scanning from far (0D) to near vision (-3D) in 0.5D steps.
VA for far and near vision with different levels of contrast, 100%, 25% and 10% by means of Sloan letter charts.
Evaluation of decentration and rotation effect, inducing ±0.5mm in x and y axis and rotating the artificial eye 0º, 120º and 240º respectively.
Performance of each lens under natural (4mm) and 3mm pupil
Figure 1: Set-up scheme where: VT. Vision Test; ME. Model Eye; IOL. IOL submerged in water; L. Lens; M. Mirror; P. Variable Pupil E. Patient’s eye; D. Display; C. Camera.
RESULTS
Throughfocus Scanning
Figure 3: Visual Acuity (logMAR) at far and near vision of the Mplus (MP) and the NDIOL-CF (ND) MIOLs for each angle to study the rotational effect.
Figure 4: Mean absolute difference of VA (logMAR) between central position and decentered positions from the optical axis (mm) of each MIOL.
Figure 2.: Visual acuity results for the throughfocus scanning for all lenses with natural pupils in high luminance conditions and 100% of contrast.
MIOL
100% Contrast
25% Contrast
10% Contrast
FVA ± SD
NVA ± SD
Monofocal (Artis.)
-0.20 ± 0.00
0.50 ± 0.00
-0.17 ± 0.00
0.53 ± 0.00
0.04 ± 0.00
0.73 ± 0.00
NDIOL –CF
-0.10 ± 0.05
-0.03 ± 0.05
0.03 ± 0.05
0.10 ± 0.05
0.17 ± 0.05
NDIOL –CN
-0.07 ± 0.05
0.06 ± 0.05
0.13 ± 0.05
MPlus
-0.10 ± 0.00
-0.05 ± 0.07
0.15 ± 0.05
MIOL
Natural Pupil
3mm Pupil
FVA ± SD
DVA ± SD
NDIOL-CF
-0.10 ± 0.05
-0.02 ± 0.05
MPlus
-0.10 ± 0.00
-0.15 ± 0.05
Table 3: Far Visual Acuity (DVA) ± SD in LogMAR units for each pupil size (3mm and Natural) in high luminance conditions.
Table 2: Far Visual Acuity (FVA) and Near Visual Acuity (NVA) in LogMAR units for each contrast level (100%, 25% and 10%) in high luminance conditions.
CONCLUSIONS
VirtIOL vision simulator can emulate any IOL design, even the more complex as are MIOLs.
Throughfocus showed a bifocal behaviour for the meausred MIOLs (Figure 2).
Good levels of VA were found for FV and NV for all measured MIOLs with 100% contrast. In terms of 25% and 10% contrast one line per level was increased also in far and near vision (Table 2).
There was no or little impact of the positioning errors on the visual performance of the IOLs (Figure 4).
There was effect on the visual performance when measuring at different rotation positions in the M-Plus lens (Figure 3).
When measuring with small pupils, M-Plus lens increased the VA, meanwhile, NDIOL lens decreased it (Table 3).
The simulations through VirtIOL in the preliminary steps of the NDIOL development helped in a design improvement of the lens.
ACKNOWLEDGEMENTS
This study was funded by the Spanish Ministry of Science and Innovation with the project grant DPI C02-01, and the European Union. A. Giner thanks the Ministerio de Economía y Competitividad for the PhD grant she received.