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AbstractDO.12.13 Comparison between raytracing and 3rd-generation IOL calculation formulae Preußner P. R.
University Eye Hospital Mainz, Germany Objective: To compare the prediction accuracy of raytracing and of the 4 mostly used 3rd-generation IOL calculation formulae.
Methods: Full aperture numerical raytracing utilizing manufacturers IOL data (anterior and posterior radius, central thickness, refractive index and asphericities, if any) is compared with the Haigis, SRK/T, Hoffer-Q and Holladay formula. 2888 normal eyes, 265 short eyes (axial length <22mm), two collectives of 59 und 50 long eyes (axial length >27mm) from 2 different hospitals and two extremely short eyes (axial lengths 16.70mm and 16.72mm) implanted with altogether 10 IOL models are included and compared with adjusted and not adjusted mean ACD, for each method as far as applicable and described in literature. Axial lengths and corneal radii are measured with the IOLMaster, Zeiss.
Results: For the adjusted calculations, prediction errors in normal eyes are approximately the same with all 5 methods (mean absolute errors approx. 0.43D). The differences between the 5 methods increase systematically in the longer, but more in the shorter eyes and are in maximum 6D in the extremely short ones, with raytracing giving the most accurate predictions.
Conclusions: The benefit of the raytracing increases with the distance from the means of the population. Raytracing accuracy can further be improved by inclusion of additionally measured data such as corneal asphericity (important after corneal refractive surgery), posterior corneal radius and pupil width.
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