Artikel
Simulated ocular-biometry effects on add-power demand in multifocal intraocular lenses
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Veröffentlicht: | 2. März 2023 |
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Gliederung
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Purpose: Although multifocal intraocular lenses (IOLs) have unique and fixed addition values, the position of the secondary peak detected in defocus-curve measurements may show high intersubject variability. In this study, the add-power demand dependency on ocular biometry was assessed by means of ray-tracing simulations.
Methods: IOL-Master biometry reports of patients scheduled for routine cataract surgery were collected. In total, 34 eyes were included with the following parameters used to build a personalized eye model: corneal keratometry (KER), anterior chamber depth (ACD), and axial length (AXL). Ray-tracing software was applied for pseudophakic eye simulations. Each model featured a biconvex lens with radii of curvature adjusted for best distance vision. Then, trial glasses with -4D, -3D, -2D, and -1.5D were placed with a vertex distance of 12 mm. The required IOL-power change to induce a desirable near/intermediate effect at the spectacle plane was calculated with respect to the far-point condition.
Results: The mean (±standard deviation) KER was 7.79 ±0.24 mm, the ACD was 3.22 ±0.60 mm, and the AXL was 23.77 ±1.34 mm. In this population, the lowest and highest add power (IOL plane) varied by 0.39D, 0.52D, 0.76D, 0.98D for the -1.5D, -2D, -3D and -4D trial glass, respectively. A high correlation was found between the observed add-power change and the ACD, indicating a linear increase of the add-power demand for larger ACD values. By contrast, the AXL and the KER demonstrated poor or no correlation with the required IOL-power adjustment.
Conclusions: The ACD, which determines the effective lens position, affects the add-power demand of a pseudophakic patient despite a full far-distance correction. The reported change may contribute to the variability in defocus curves of multifocal patients observed clinically.