Multifocal Intraocular Lenses and Corneal Refractive Surgery

Purpose To numerically evaluate and compare the tolerance to misalignment and tilt of aspheric intraocular lenses (IOLs) designed for three eyes: with standard cornea and with simulated corneas after myopic and hyperopic laser ablation surgery. Methods Three aspheric IOLs of +20.00 diopter (D) with different spherical aberration (SA) (Z40) values have been designed using a theoretical model eye. Drastic changes on the theoretical eye anterior corneal asphericity have been performed to simulate myopic and hyperopic refractive surgeries. The effect of IOL misalignment and tilt on the image quality has been evaluated using a commercial optical software design for the three eye models. Image quality was assessed from the modulation transfer function (MTF), root mean square (RMS) values of defocus, astigmatism, coma and spherical aberration (Z40), and retinal images obtained from a visual simulator using an aleatory optotype of 0.00 LogMar visual acuity (VA). Results IOL misalignment and tilt reduced MTF values in general, and increased wavefront aberrations errors. Aberration-free IOLs maintained best the MTF values when misalignments were applied, together with good on-axis optical quality. IOLs with negative SA (Z40) correction decreased the MTF value under 0.43 for misalignments values higher than 0.50 mm with the three corneas. The effect of misalignment on RMS astigmatism and coma was correlated with the IOL SA (Z40) and with the three corneas. Conclusions This theoretical study shows that the largest degradation in image quality arises for the IOL with the highest amount of spherical aberration (Z40). Moreover, it has been found that the aspherical design has a more influential role in misalignment tolerance than in tilt tolerance.

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Factors Affecting Prediction Error after Cataract Surgery with Implantation of Various Multifocal IOLs in Patients with Previous Refractive Laser Surgery

10.21203/rs.3.rs-133095/v1 ◽

2020 ◽

Author(s):

Young-Sik Yoo ◽

Min Chae Kang ◽

Jongyeop Park ◽

Hyung-Goo Kwon ◽

Eui-Sang Chung ◽

...

Keyword(s):

Visual Acuity ◽

Cataract Surgery ◽

Prediction Error ◽

Refractive Surgery ◽

Predictive Accuracy ◽

Absolute Error ◽

Intraocular Lenses ◽

Group I ◽

Iol Power ◽

Corneal Refractive Surgery

Abstract This study aimed to compare the clinical outcomes of implantation of various multifocal intraocular lenses (mIOLs) and the prediction accuracy of two intraocular lens (IOL) power calculation formulas for eyes that underwent previous corneal refractive surgery. Four types of mIOLs (TECNIS Symfony (Group I), AcrySof IQ PanOptix (Group II), LENTIS Mplus (Group III), and TECNIS mIOL (Group IV)) were used and the IOL power was calculated with the two no-history methods, Shammas-PL and Barrett True-K. Visual acuity and refractive outcomes including manifest refraction, prediction error (PE), absolute error (AE), and median absolute error (MedAE) were evaluated at three months after the cataract surgery. For all groups the Barrett True-K formula produced a narrower range of PEs and lower MedAE than Shammas-PL. Eyes of lower predictive accuracy (group B, AE > 0.5D) showed weak uncorrected distance visual acuity resulting from myopic refractive error and target refraction when compared to that of higher predictive accuracy (group A, AE ≤ 0.5 D). Targeting emmetropia using the Barrett True-K is recommended in patients undergoing mIOL implantation with prior corneal refractive surgery. Additionally, history of prior large amount of laser ablation seems to be an important factor related to low predictive accuracy.

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