Abstract
Purpose :
Literature shows that the tolerance to residual refractive errors (TRE) varies for different intraocular lens (IOL) designs. While patients with multifocal IOLs generally do not tolerate residual astigmatism well, and astigmatism as low as 0.5 D to 0.75 D can affect their visual acuity, extended depth of focus (EDOF) IOLs are less sensitive with an acceptable threshold of residual astigmatism of approximately 1D. The purpose of this study is to preclinically evaluate the TRE of different IOL models.
Methods :
Visual performance of an aspheric monofocal (M1), an aspheric monofocal designed to slightly extend depth of focus (M2), a diffractive bifocal (B) (+3.25D add power) and diffractive EDOF IOL designs were evaluated with corrected cylinder and in the presence of up to 1D of residual astigmatism. A set of 46 physiological model eyes that included higher order aberrations were used to predict the clinical defocus curves for the four IOL models. The percentage of eyes with 20/20 or better visual acuity (pVA) in the presence of residual defocus or astigmatism were considered as the metric to evaluate TRE.
Results :
When all refractive errors are corrected, the pVA was similar for all lens models. In the presence of 0.5D of residual defocus, both monofocals and the EDOF design showed a greater tolerance, with up to 80%, 100% and 60% of patients having 20/20 VA or better, for M1, M2 and the EDOF IOL, respectively. With the same level of residual defocus, the pVA was reduced to 15% for the multifocal IOL, indicating a lower tolerance to residual defocus. When 0.75D of astigmatism was induced, the pVA was similar (96% for M1, 98% for M2 and 91% for the EDOF), while it was drastically reduced to 35% for the multifocal design, indicating a lower tolerance to astigmatism as well.
Conclusions :
This study preclinically assessed the TRE of different IOL models. Computer simulations showed that the monofocal aspheric, the monofocal design to slightly extend depth of focus and diffractive EDOF IOLs preserve high levels of visual acuity in the presence of residual defocus and astigmatism, while multifocal IOLs are more sensitive to them, demonstrating the robustness of the diffractive EDOF IOL and the limited tolerance of multifocal IOLs, as reported in the literature. Therefore, this study validates the use of computer simulations to evaluate the TRE of IOLs.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.