Theoretical image performance with customized aspheric and spherical IOLs – when do we get a benefit from customized aspheric design?

Langenbucher, Achim; Janunts, Edgar; Seitz, Berthold; Kannengießer, Marc; Eppig, Timo

doi:10.1016/j.zemedi.2013.05.001

Cited by 10 publications

(5 citation statements)

References 38 publications

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“…Several schematic model eyes such as the Liou‐Brennan Model Eye (LBME) are accepted as basis for aberration‐correcting designs; however some IOL designs are based on proprietary model eyes and customized IOLs are derived using model eyes based on individual patient data (Langenbucher et al. , ; Zhu et al. ).…”

Section: Introductionmentioning

confidence: 99%

Index of contrast sensitivity (ICS) in pseudophakic eyes with different intraocular lens designs

Eppig

Filser

Goeppert

et al. 2014

Acta Ophthalmologica

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ABSTRACT.Purpose: To evaluate the index of contrast sensitivity (ICS) in eyes after cataract surgery with various intraocular lens designs and to compare with the area under log contrast sensitivity curve (AULCSF). Methods: The study comprised 395 eyes of 198 patients in the age of 73.1 AE 7.86 years receiving 11 different aspheric IOL designs (aberration-free and correcting) and a spherical (IOL) as control group. Follow-up examination after bilateral cataract surgery was completed within 71 AE 21.4 days after second IOL implantation. Patients underwent complete examination and biometry before surgery. The follow-up examination included visual acuity, pupil diameter, residual spherical aberration and mesopic as well as photopic contrast sensitivity (CS) measured with the Optec 6500 Functional Vision Analyzer. From the contrast sensitivity, we calculated the ICS according to Haughom and Strand. Results: The median mesopic ICS was À144, À131 and À85, and the median photopic ICS was À289, À285 and À212 for the spherical, aberration-free and aberration-correcting IOL group, respectively. While we could not detect a significant difference between the aberration groups in some spatial frequencies, the ICS showed a significant difference between the aberration-correcting and the aberration-free or the spherical group, respectively. No significant difference was found between the aberration-free and the spherical group. Conclusions: The ICS is a useful index for evaluation of overall CS and comparison of different patient groups. With aberration-correcting IOLs, ICS was statistically better than with aberration-free or spherical IOLs, whereas the latter two showed no significant difference.

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Section: Introductionmentioning

confidence: 99%

Index of contrast sensitivity (ICS) in pseudophakic eyes with different intraocular lens designs

Eppig

Filser

Goeppert

et al. 2014

Acta Ophthalmologica

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“…Individual assessment of pupil size and dynamics along with other ocular characteristics will allow further IOL customization to each patient (14). Patients with large pupils may benefit more from aspheric IOLs, because uncorrected spherical aberration can cause significant image deterioration (31). The asphericity of aspheric IOLs should ideally be chosen according to the aberrations calculated from the central part of the cornea that corresponds with the entrance pupil.…”

Section: Discussionmentioning

confidence: 99%

Reproducibility and normal values of static pupil diameters

Schröder

Chashchina

Janunts

et al. 2018

European Journal of Ophthalmology

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“…Both surfaces were considered as quadric surfaces described by a central radius of curvature (R a or R b ) and an asphericity (Q a and Q b ). The axial symmetry of this model means that restriction to a 2-dimensional raytracing strategy was sufficient (Langenbucher et al 2006;Langenbucher et al 2011;Langenbucher et al 2014;Langenbucher et al 2016). The apex of the corneal front surface was assumed to be located at z = 0 and the corneal back surface apex at a distance of z = CCT.…”

Section: Measurement Datamentioning

confidence: 99%

“…The diameter of the ray bundle was adjusted to the measured diameter of the pupil PUP. Then, the ray-surface intersection was calculated and the direction of the refracted rays was derived using Snell's law for the corneal front surface (Langenbucher et al 2006;Langenbucher et al 2011;Langenbucher et al 2014;Langenbucher et al 2016). After tracing all rays through the cornea, ray intersection with the corneal back surface was calculated and the direction of the refracted rays in the anterior chamber was derived using the Snell's law.…”

Section: Measurement Datamentioning

confidence: 99%

Back‐calculation of keratometer index based on OCT data and raytracing – a Monte Carlo simulation

Langenbucher

Szentmáry

Weisensee

et al. 2021

Acta Ophthalmologica

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Purpose: This study aims to develop a raytracing-based strategy for calculating corneal power from anterior segment optical coherence tomography data and extracting the individual keratometer index, which converts the corneal front surface radius to corneal power. Methods: A large OCT dataset (10,218 eyes of 8,430 patients) from the Casia 2 (Tomey, Japan) was post-processed in MATLAB (MathWorks, USA). Radius of curvature, asphericity of the corneal front and back surface, central corneal thickness and pupil size (aperture) were used to trace a bundle of rays through the cornea and derive the best focus plane. Corneal power was calculated with respect to the corneal front vertex plane, and the keratometer index was backcalculated using corneal power and front surface radius. Keratometer index was analysed in a multivariate linear model. Results: The averaged resulting keratometer index was 1.3317 AE 0.0017 with a median of 1.3317 and range from 1.3233 to 1.3390. In a univariate model, only the front surface asphericity affected the keratometer index. The multivariate model for modelling the keratometer index using all 6 input parameters performed very well (RMS error: 5.54e-4, R 2 : 0.90, significance vs. constant model: <0.0001). Conclusions: In the classical calculation, the keratometer index used for converting corneal radius to dioptric power uses several model assumptions. As these assumptions are not generally satisfied, corneal power cannot be calculated from corneal front surface radius alone. Considering all 6 input variables, the linear prediction model performs well and can be used if all input parameters are measured with a tomographer.

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Theoretical image performance with customized aspheric and spherical IOLs – when do we get a benefit from customized aspheric design?

Cited by 10 publications

References 38 publications

Index of contrast sensitivity (ICS) in pseudophakic eyes with different intraocular lens designs

Index of contrast sensitivity (ICS) in pseudophakic eyes with different intraocular lens designs

Reproducibility and normal values of static pupil diameters

Back‐calculation of keratometer index based on OCT data and raytracing – a Monte Carlo simulation

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