Comparing the Visual Performance of Multifocal IOLs With Different Add Powers Tested in 3 Pre-Clinical Setups
Purpose
Explore the impact of changing Multifocal IOL add power when measured on an optical bench, measured using an adaptive optics vision simulator (AOVS) and as obtained from computer based simulations.
Methods
Optical properties of diffractive bifocal IOLs with add powers between 2.75 and 4.00D at the IOL plane were evaluated in different laboratory settings. Measurements included best and through-focus Modulation Transfer Function (MTF) testing on an optical bench, and computer simulated monocular defocus curves. High contrast binocular through-focus visual acuity (BTFVA) was measured on five subjects using an AOVS with SLOAN letters in white light for a 3.5mm pupil. Bilateral induction of phase profiles corresponding to the same add power as well as phase profile combinations were tested to explore the consequences of mixing and matching lenses of different add powers.
Results
Visual performance at far and near distances was independent of add power. On an optical bench, the MTF values in white light for a 3mm pupil were between 0.25 and 0.30 in both foci for all add powers. An increased intermediate vision was observed for IOLs with lower add powers both in the simulated monocular defocus curves and in the BTFVA measured with AOVS. Combining the 4.0D and 2.75D add phase profiles at the AOVS resulted in a visual acuity of 0.1LogMAR or better over a defocus range from -1.5 to -3.0D in the spectacle plane.
Conclusion
Changing the add power of multifocal IOLs, having the same diffractive profile, does not affect in-focus near and far vision in the settings tested. Preclinical testing indicates that intermediate VA will increase when add power is reduced. Binocular AOVS testing shows that combining different add powers further improves intermediate vision.