Preliminary evaluation of an algorithm to minimize the power error selection of an aspheric intraocular lens by optimizing the estimation of the corneal power and the effective lens position

Abstract:

AIM: To evaluate the refractive predictability achieved with an aspheric intraocular lens(IOL)and to develop a preliminary optimized algorithm for the calculation of its power(P_IOL).

METHODS: This study included 65 eyes implanted with the aspheric IOL LENTIS L-313(Oculentis GmbH)that were divided into 2 groups: 12 eyes(8 patients)with P_IOL≥23.0 D(group A), and 53 eyes(35 patients)with P_IOL<23.0 D(group B). The refractive predictability was evaluated at 3mo postoperatively. An adjusted IOL power(P_IOLadj)was calculated considering a variable refractive index for corneal power estimation, the refractive outcome obtained, and an adjusted effective lens position(ELP_adj)according to age and anatomical factors.

RESULTS: Postoperative spherical equivalent ranged from -0.75 to +0.75 D and from -1.38 to +0.75 D in groups A and B, respectively. No statistically significant differences were found in groups A(P=0.64)and B(P=0.82)between P_IOLadj and the IOL power implanted(P_IOLReal). The Bland and Altman analysis showed ranges of agreement between P_IOLadj and P_IOLReal of +1.11 to -0.96 D and +1.14 to -1.18 D in groups A and B, respectively. Clinically and statistically significant differences were found between P_IOLadj and P_IOL obtained with Hoffer Q and Holladay I formulas(P<0.01).

CONCLUSION: The refractive predictability of cataract surgery with implantation of an aspheric IOL can be optimized using paraxial optics combined with linear algorithms to minimize the error associated to the estimation of corneal power and ELP.

Key words:aspheric intraocular lens; intraocular lens power calculation; effective lens position