There is inter-subject variability in position of secondary peaks in defocus-curves among patients who received the same multifocal intraocular lens (IOL). This study used ray-tracing simulations to assess the dependency of add-power demand on ocular biometry. David J. Apple Laboratory for Ocular Pathology. Experimental study. Optical biometry of 34 patients scheduled for routine cataract surgery was collected and the following parameters used to build a personalized eye model: keratometry (K), anterior chamber depth (ACD), and axial length (AL). Ray-tracing software was applied for pseudophakic-eye simulations. Each model featured a biconvex lens with radii of curvature adjusted for best distance-vision. Trial glasses with -4D, -3D, -2D, and -1.5D were placed in front of a virtual eye. The IOL-power change required to induce a desirable near/intermediate effect at the spectacle plane was calculated with respect to the far-point condition. Mean values for K, ACD, and AL were 7.79±0.24mm, 3.22±0.60mm, and 23.77±1.34mm, respectively. The lowest and highest add power (IOL plane) varied by 0.39D, 0.52D, 0.76D, 0.98D for -1.5D, -2D, -3D and -4D trial glasses, respectively. 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. The AL and the K demonstrated poor or no correlation with the required IOL-power adjustment. The ACD, which determines the effective lens position in our model, has greater impact on add-power demand than AL or K. The reported change may contribute to inter-subject variability in defocus curves of multifocal patients.
Son et al. (Thu,) studied this question.
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