OPTICAL PERFORMANCE OF MONOFOCAL IOLS: EFFECTS OF SURFACE ASPHERICITY IN VARIED CONDITIONS

Monofocal IOLs make up the majority of implants, varying not only in biomaterials but also in surface asphericity. Aspheric IOLs aim to reduce spherical aberration (SA), although this may affect tolerance to misalignment. This study compared monofocal IOLs of different asphericity, assessing their optical quality in on- and off-axis configurations.

David J. Apple Center for Vision Research, Department of Ophthalmology, University of Heidelberg, Germany

Three aspheric monofocal models were included. Clareon CNA0T0 (Alcon) applies an SA correction of 0.20μm to lower corneal aberrations. MX60 (B&L) has aberration-free optics aimed to preserve a natural SA level. CT Lucia 621P (Zeiss) features changing asphericity distribution with central negative and peripheral positive SA intended to minimize the impact of aberrations and misalignment. The IOLs’ optical function was assessed under various conditions, including low and high levels of corneal SA, monochromatic and white-light conditions, as well as photopic and scotopic pupil size. The impact of lens misalignment was tested by gradually decentering the IOLs.  

For photopic pupil, the three models demonstrated close behavior in white light; however, MX60 was most affected by condition change. In simulated scotopic eye and average corneal SA, Clareon demonstrated minimally improved performance, but differences between the models were more pronounced in monochromatic rather than white light. Interestingly, CT Lucia performed slightly better than MX60 for the condition without SA, while Clareon demonstrated poor performance. For small pupils, the impact of decentration on CT Lucia and MX60 was minimal, while Clareon’s contrast was reduced. Increased pupil size exacerbated the effect of IOL decentration.

Surface asphericity influences the monofocal-IOL performance, depending on corneal SA and light spectrum. Although a high SA correction offers advantages in scotopic conditions, these benefits may be diminished by off-axis lens position. The non-uniform asphericity appears to be more robust in such cases while still mitigating SA effects.