Customized intraocular lenses

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Chad O’Neal’
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1 Customized intraocular lenses Challenges and limitations Achim Langenbucher, Simon Schröder & Timo Eppig

$Aspherical IOL Diffractive multifocal$ IOL Spherical IOL Customized IOL

2 Customized IOL what does this mean? Aspherical IOL Diffractive multifocal IOL Spherical IOL Customized IOL Refraktive multifocal IOL Toric IOL Accommodative IOL 2

3 Wavefront decomposition into characteristic polynomials Frits Zernike Nobel price winner

4 Cataract surgery or refractive surgery? Implantation of an individual IOL into the capsular bag Replacement of the opaque crystalline lens CLE Implantation of an additional individual lens into a phakic or pseudophakic eye Phakic IOL, ICL Add-on lens The strategy strictly differs in both situations!!! 4

5 Cataract surgery Implantation of an individual lens in the capsular bag requires: Knowledge of the exact corneal shape Topography of front and back surface Corneal thickness profile Visual axis relative to corneal shape measurement Axial length of the eye (along visual axis) Pupil geometry Corneal tomography Reliable prediction of postop IOL position in the eye (axial, lateral, tilt, ) 5

6 Refractive surgery Implantation of an individual additional lens requires: Knowledge of the optical aberrations of the eye (e.g. wavefront measurement ) in the IOL plane Reliable prediction of postop IOL position in the eye (axial, lateral, tilt, ) Pupil geometry In case we do not know optical aberrations in the IOL plane Transformation of the wavefront from measurement plane (e.g. spectacle plane) to IOL plane through the cornea based on corneal shape Topography of corneal front and back surface Corneal thickness profile Corneal tomography 6

7 Why customized IOL? Approx 20% of the population suffer from deteriorated spectacle corrected vision less than 20/20 due to optical aberrations In most cases due to corneal shape, rarely due to lens geometry Optical implants have a stable mechanical coupling to the eye and therefore are priviledged for aberration correction 1. Cataract surgery: corneal associated aberrations 2. Refractive surgery (additional IOL): Total aberrations of the eye can be in part or totally corrected with individual IOL Enhancement of contrast transfer Reduction of glare, halos, ghost images with poor lighting conditions Improvement of visual performance Kingston AC, Cox IG. Optom Vis Sci. 2013; Mita N, et al. J Cataract Refract Surg Schoneveld P, Pesudovs K, Coster DJ. Clin Exp Optom Berrio E, Tabernero J, Artal P. J Vis

$IOL (with negative SA) may reduce or fully correct corneal SA One size fits all does not work for SA correction spherical aspherical Scholz K, et al. J Cataract Refract Surg.$

8 First step in individual IOL: Correction of SA The cornea shows in general a positive spherical aberration SA A spherical IOL implanted in the eye adds some SA to the system An aspherical IOL (with negative SA) may reduce or fully correct corneal SA One size fits all does not work for SA correction spherical aspherical Scholz K, et al. J Cataract Refract Surg. 2009; 35:

9 Requirements of customized IOLs But Large individual scatter in the population One size fits all does not work! Therefore sometimes refractive surprises after implantation of aspherical SA correcting IOL. Tolerance/robustness to positioning errors Spherical IOL designs are robust the more an IOL deviates from the spherical design the more sensitive to positioning errors Translation & rotation (6 DoF!) Pseudo-accommodation should be maintained (near vision!) Simulation in an entire optical model (with cornea) mandatory, if necessary superposition with a diffractive structure Phakic IOL Ho do wavefront aberrations change during accommodation? What happens if the crystalline lens opacifies? Kingston AC, Cox IG. Optom Vis Sci. 2013; Mita N, et al. J Cataract Refract Surg Schoneveld P, Pesudovs K, Coster DJ. Clin Exp Optom Berrio E, Tabernero J, Artal P. J Vis

10 Strategy: Cataract surgery with customized IOL Discrete data points to closed surface Axial length of the eye and distances of the components Pupil geometry and visual axis Fovea Individual model eye 10

$Strategy: Refractive surgery mit customized IOL If optical$ Discrete data points to closed surface Pupil geometry and visual axis

11 Strategy: Refractive surgery mit customized IOL If optical aberrations are not measured in the IOL plane: -> corneal tomography Discrete data points to closed surface Pupil geometry and visual axis Transformation from measurement plane to IOL plane Fovea Individual model eye 11

12 Indications for customized IOL? Stable corneal shape!!! At least 6 months Repeat measurements of corneal topo-/tomography Consider the effect of tear film fluctuations Stabil axial length Predictable and reliable positioning of the IOL in the eye with cataract surgery: no PEX or zonular weakness With refractive surgery: stable fixation of the phakic or add-on IOL in the ciliary sulcus Best candidates to start (Stationary) forme-fruste keratoconus Situation after decentred refractive corneal surgery pterygium surgery keratoplasty 12

$with simplifications/restrictions) All refractive surfaces in the eye can be represented with Quadric surfaces biconic surfaces Zernike polynomials Splines (e.g.$

13 Calculation of customized IOL with raytracing Individual software (e.g. with simplifications/restrictions) All refractive surfaces in the eye can be represented with Quadric surfaces biconic surfaces Zernike polynomials Splines (e.g. bi-cubic, bi-quadric) Both corneal surfaces are characterized with such a definition One IOL surface is predefined The other IOL surface is individually optimized Quadric: Professional raytracing software Z.B. ZEMAX, CodeV, Raytrace, global definition local definition Biconic: Zhu Z, Janunts E, Eppig T, Sauer T, Langenbucher A. Curr Eye Res 2011; 36: Langenbucher A, Eppig T, Seitz B, Janunts E. Curr Eye Res. 2011; 36: Langenbucher A, Janunts E, Seitz B, Kannengießer M, Eppig T. Z Med Phys. 2014; 24:

14 Optimization criterion for the individual surface Minimization of the wavefront error Maximization of the MTF Maximization of Strehl ratio or PSF 14

15 Case 1: Patient 15 years following myopic LASIK Biometry: Axial length mm ACD 3.56 mm Estimated ELP 5.3 mm 2 IOL options Aperture 3 mm and 5.3 mm (at pupil plane) Individual IOL front surface 15

16 Case 1: IOL 1 with low grade of individual correction Tilt 0 / 90, defocus, astigmatism 0 / 45, spherical aberration IOL height minus defocus and astigmatism x10-3 mm 16

17 Fall 1: Patient 15 Jahre nach myoper LASIK IOL 1: PSF 3 mm pupil IOL 1: PSF 5.3 mm pupil IOL 1: MTF 3 mm pupil IOL 1: MTF 5.3 mm pupil 17

18 Case 1: IOL 2 with high grade of individual correction Full correction with Zernike degree n=4 IOL height minus defocus and astigmatism x10-3 mm 18

19 Fall 1: Patient 15 Jahre nach myoper LASIK IOL 2: PSF 3 mm pupil IOL 2: PSF 5.3 mm pupil IOL 2: MTF 3 mm pupil IOL 2: MTF 5.3 mm pupil 19

20 Case 2: Patient 10 years after penetrating keratoplasty Biometry: Axial length mm ACD 3.36 mm Estimated ELP 5.1 mm 2 IOL options Aperture 3 mm and 5.3 mm (at pupil plane) Individual IOL front surface 20

21 Case 2: IOL 1 with low grade of individual correction Tilt 0 / 90, defocus, astigmatism 0 / 45, spherical aberration IOL height minus defocus and astigmatism x10-3 mm 21

22 Fall 2: Patient 10 Jahre nach perf. Keratoplastik IOL 1: PSF 3 mm pupil IOL 1: PSF 5.3 mm pupil IOL 1: MTF 3 mm pupil IOL 1: MTF 5.3 mm pupil 22

23 Case 2: IOL 2 with high grade of individual correction Full correction with Zernike degree n=4 IOL height minus defocus and astigmatism x10-3 mm 23

24 Fall 2: Patient 10 Jahre nach perf. Keratoplastik IOL 2: PSF 3 mm pupil IOL 2: PSF 5.3 mm pupil IOL 2: MTF 3 mm pupil IOL 2: MTF 5.3 mm pupil 24

25 Fall 2: IOL 2 um 0,4 mm lateral dezentriert IOL 2: PSF 3 mm pupil IOL 2: PSF 5.3 mm pupil IOL 2: MTF 3 mm pupil IOL 2: MTF 5.3 mm pupil IOL 2 laterally decentered by 0.4 mm 25

26 How do we evaluate individual surfaces? Before implantation Topographic measurement of individual IOL surfaces before IOL implantation Comparison actual vs. target Simulation and modelling with actual and target geometry of the IOL After implantation Evaluation of visual performance Quantitative Wavefront analysis Qualitative Contrast sensitivity measurement VA (standard / with glare) and photopic/mesopic Kannengießer M, Langenbucher A, Janunts E. Individual IOL surface topography analysis by the WaveMaster Reflex UV. Biomed Res Int Langenbucher A, Janunts E, Seitz B, Kannengießer M, Eppig T. Theoretical image performance with customized aspheric and spherical IOLs - whendo we get a benefit from customized aspheric design? Z Med Phys Langenbucher A, Eppig T, Seitz B, Janunts E. Customized aspheric IOL design by raytracing through the eye containing quadric surfaces. Curr Eye Res Kannengießer M, Zhu Z, Langenbucher A, Janunts E. Evaluation of free-form IOL topographies by clinically available topographers. Z Med Phys Zhu Z, Janunts E, Eppig T, Sauer T, Langenbucher A. Tomography-based customized IOL calculation model. Curr Eye Res

27 Discussion How much individual is reasonable? The concept behind customized IOL is clear Important: for cataract surgery: preoperative tomography and biometry for refractive surgery (phakic or add-on): preoperative aberrometry!!! Proof of concept always with aberrometry Unsolved issues: How precise can free form surfaces be manufactured? How precise can individual IOL surface be measured? How predictable and reliable is the positioning of an IOL in the eye? Translations, rotations What changes in a long term? Wound healing, tomography, distances, pupil How to maintain pseudo-accommodation? What is the overall benefit for the patient? 27

28 Limitations Complex manufacturing process and quality management High costs, sample size n=1 + stand-by Production and validation interval: waiting for the patient Cost-benefit ratio reasonable for standard cases? The first 5 implantation are now planned No experience with long term follow-up 28

29 Take-home-message Customized IOL have clear benefits for individuals with impaired vision due to corneal pathologies such as keratoconus or irregularities WITH CLEAR OPTICAL MEDIA With dominant corneal aberrations small fluctuations in HOA or tear film irregularities may play a minor role for the long term result the happy patient!!! As HOA may vary over time and there might be iatrogenic changes due to surgery correction should be performed with a conservative planning strategy The higher the grade of correction the more sensitive is the IOL for positioning errors The clinical results will show whether the cost and efforts are balanced by the benefit for the patients 29

30 Thank you for your kind attention Achim Langenbucher Institute for Experimental Ophthalmology Saarland University Kirrberger Str. 100, Bldg Homburg (Saar) 30

Principles and clinical applications of ray-tracing aberrometry (Part II)

UPDATE/REVIEW Principles and clinical applications of ray-tracing aberrometry (Part II) Alfredo Castillo Gómez, MD, PhD 1 ; Antonio Verdejo del Rey, OD 2 ; Carlos Palomino Bautista, MD 3 ; Ana Escalada