Error induced by the estimation of the corneal power and the effective lens position with a rotationally asymmetric refractive multifocal intraocular lens

AIM

To evaluate the prediction error in intraocular lens (IOL) power calculation for a rotationally asymmetric refractive multifocal IOL and the impact on this error of the optimization of the keratometric estimation of the corneal power and the prediction of the effective lens position (ELP).

METHODS

Retrospective study including a total of 25 eyes of 13 patients (age, 50 to 83y) with previous cataract surgery with implantation of the Lentis Mplus LS-312 IOL (Oculentis GmbH, Germany). In all cases, an adjusted IOL power (P_IOLadj) was calculated based on Gaussian optics using a variable keratometric index value (n_kadj) for the estimation of the corneal power (P_kadj) and on a new value for ELP (ELP_adj) obtained by multiple regression analysis. This P_IOLadj was compared with the IOL power implanted (P_IOLReal) and the value proposed by three conventional formulas (Haigis, Hoffer Q and Holladay I).

RESULTS

P_IOLReal was not significantly different than P_IOLadj and Holladay IOL power (P>0.05). In the Bland and Altman analysis, P_IOLadj showed lower mean difference (-0.07 D) and limits of agreement (of 1.47 and -1.61 D) when compared to P_IOLReal than the IOL power value obtained with the Holladay formula. Furthermore, ELP_adj was significantly lower than ELP calculated with other conventional formulas (P<0.01) and was found to be dependent on axial length, anterior chamber depth and P_kadj.

CONCLUSION

Refractive outcomes after cataract surgery with implantation of the multifocal IOL Lentis Mplus LS-312 can be optimized by minimizing the keratometric error and by estimating ELP using a mathematical expression dependent on anatomical factors.