Medical Director - R & D Consultant, Ziemer Group AG, Port, SwitzerlandMedical Director - R & D Consultant, Ziemer Group AG, Port, Switzerlandcarlos.arce@ziemergroup.comcarlos.arce@ziemergroup.com

Speaker, Bausch & Lomb do Brasil Speaker, Bausch & Lomb do Brasil Territory Manager for Latin America, Vista Optics Limited, Widnes, UKTerritory Manager for Latin America, Vista Optics Limited, Widnes, UK

Author does not have financial interest in the commercialization of equipments mentionedAuthor does not have financial interest in the commercialization of equipments mentioned

Carlos G. Arce, MDCarlos G. Arce, MD

Selection of IOL using total corneal Selection of IOL using total corneal wave front analysiswave front analysis

Associate Researcher and Ophthalmologist Ocular Bioengineering & Refractive Surgery Sectors,

Institute of Vision, Department of Ophthalmology, Paulista School of Medicine, Federal University of São Paulo, Brazil

1. Sim K: Only from anterior surface (thin lens formula)2. Gaussian: True Net Power, Total-Mean Power, Equivalent Power, (thick

lens formula)3. Ray-Tracing: Total-Optical Power, Total Corneal Power Best value for IOL calculation

Three Corneal PowersThree Corneal Powers

New Trends in Corneal TopographyNew Trends in Corneal Topography

1

3

1 3

Snell’s Law:

)sin()sin( 2211 nn

Index of refractions (n):- Air 1- Human Cornea1.376- Aqueos Humor1.336

New Trends in Corneal TopographyNew Trends in Corneal Topography

TCP Average - Ray Traced 0-4 mmTCP Average - Ray Traced 0-4 mm

• Post-Hyperopic LASIK

• Post-Myopic LASIK

TCP Average - Ray Traced 0-4 mmTCP Average - Ray Traced 0-4 mm

Pre- and Post- Pre- and Post- refractive surgery refractive surgery

Total Corneal PowerTotal Corneal PowerAverage for Average for

IOL CalculationIOL Calculation

0

Age 25 Age 45 Age 65 Age 85

Cornea ≈ +0.20 Whole Eye

Lens

• Glasser & Campbell. Vision Res, 1998: 38 (2); 209• Artal et al. J. Opt. Soc. Am. A. Feb 2002

PseudophakiaWith Standard IOL

+

Spherical Aberration and AgeSpherical Aberration and Age

New Trends in Corneal TopographyNew Trends in Corneal Topography

• Total SA of the eye increases with age because lens changes• Total corneal SA does not change with age in normal corneas• After cataract surgery only corneal SA remains

• Standard (SA = +0.18 μm)

• AcrySof IQ (SA = -0.20 μm)

• Tecnis (SA = -0.27 μm)

• SofPort AO (SA = 0 μm)• Rayner (SA = 0 μm)

Custom Selection of IOLCustom Selection of IOL

New Trends in Corneal TopographyNew Trends in Corneal Topography

• Galilei measures the total corneal wave front from both surfaces

• Spherical aberration is linked to contrast sensitivity• SA=0 gives sharpness of vision• Larger SA gives depth of focus (multifocal cornea)• Use corneal spherical aberration to determine best IOL

central rays

focus beyond

outer rays

central rays

focus in front of

outer rays

All rays are

focused at

same point

0.29μm -0.22 D

• Standard (SA = +0.18 μm)

• AcrySof IQ (SA = -0.20 μm)

• Tecnis (SA = -0.27 μm)

• SofPort AO (SA = 0 μm)• Rayner (SA = 0 μm)

Custom Selection of IOLCustom Selection of IOL

New Trends in Corneal TopographyNew Trends in Corneal Topography

• Cornea becomes more prolate• Q factor and Є2 increases• Positive SA reduces• Around Є2 = 0.55 then SA = 0 • Є2 > 0,60 then SA is already negative

• Cornea becomes less prolate or oblate• Q factor and Є2 are reduced • Positive SA increases

central rays

focus beyond

outer rays

central rays

focus in front of

outer rays

All rays are

focused at

same point

• Standard (SA = +0.18 μm)

• AcrySof IQ (SA = -0.20 μm)

• Tecnis (SA = -0.27 μm)

• SofPort AO (SA = 0 μm)• Rayner (SA = 0 μm)

Custom Selection of IOLCustom Selection of IOL

New Trends in Corneal TopographyNew Trends in Corneal Topography

• If corneal SA is positive (post-myopic LASIK) then use a negative SA IOL

• If corneal SA is negative (post-hyperopic LASIK) then use a positive SA IOL

• If patient was happy with visual quality before cataract then use neutral SA IOL

central rays

focus beyond

outer rays

central rays

focus in front of

outer rays

All rays are

focused at

same point

+0.29μm -0.22 D

Custom Selection of Target RefractionCustom Selection of Target Refraction

• Normal eye without refractive surgery• SA is positive (µm) or negative (D) then we may use a plano or negative target refraction

+0.28 μm -0.22 D

central rays

focus in front of

outer rays

All rays are

focused at

same point

Custom Selection of Target RefractionCustom Selection of Target Refraction

• Post-myopic LASIK• When corneal SA is positive (µm) or negative (D) then use a plano or negative refraction

+0.94 μm -0.72 Dcentral rays

focus in front of

outer rays

Custom Selection of Target RefractionCustom Selection of Target Refraction

• Post-hyperopic LASIK• When corneal SA is negative (µm) or positive (D) then use a plano or small positive target refraction

- 0.81 μm 0.62 Dcentral rays

focus beyond

outer rays

Custom Selection of IOLCustom Selection of IOL

• Use 3rd and 4th order corneal HOAs to determine best patient for multifocal IOLs

• If larger coma (>40 μm), trefoil (>30 μm) and/or quatrefoil (>30 μm) pupil-dependant multifocal IOLs should not be implanted

-1.06μm / -0.54μm

0.91 D @ 62.7°

• Coma is linked to KC progression

•Coma is linked to asymmetry of aspheric curvature change

• Trefoil and quatrefoil are related to irregular paracentral corneas and halos (PMD, edema)

• Eyes with larger pupils are not good candidates due to more HOAs going in

• Standard (SA = +0.18 μm)

• AcrySof IQ (SA = -0.20 μm)

• Tecnis (SA = -0.27 μm)

• SofPort AO (SA = 0 μm)• Rayner (SA = 0 μm)

All rays are

focused at

same point

Custom Selection of IOLCustom Selection of IOL

• Standard (SA = +0.18 μm)

• AcrySof IQ (SA = -0.20 μm)

• Tecnis (SA = -0.27 μm)

• SofPort AO (SA = 0 μm)• Rayner (SA = 0 μm)

All rays are

focused at

same point

Custom Selection of IOLCustom Selection of IOL

BFS & BFTABFS & BFTA

New Trends in Corneal TopographyNew Trends in Corneal Topography

BFS compares the cornea as ellipse against and ideal sphere

BFTA compares an ideal ellipse against the cornea

BFS & BFTABFS & BFTA

• Also use BFTA map patterns to preview outcome of aspheric multifocal IOLs K-A Index

• Symmetry of aspheric curvature change: Complete green BFTA maps

• Asymmetry of aspheric curvature change: larger coma and Kranemann-Arce index

Ant BFS Ant BFTA Ant BFS Ant BFTA

Post BFS Post BFTA Post BFS Post BFTA

Ant BFS Ant BFTA Ant BFS Ant BFTA

Post BFS Post BFTA Post BFS Post BFTA

• High positive Є2

• High negative Q

• Higher negative SA

• Low positive Є2

• High positive Q

• Higher positive SA

Corneal AstigmatismCorneal Astigmatism

ODKPI = 8.9 %

Thinnest = 500 μm

OSKPI = 12.9 %

Thinnest = 498 μm

New Trends in Corneal Topography

BFS & BFTABFS & BFTA

ODKPI = 8.9 %

Thinnest = 500 μm

OSKPI = 12.9 %

Thinnest = 498 μm

New Trends in Corneal Topography

• Multifocal ant. surface • KPI of 22.8%, • KProb of 39.2% • Total corneal astigmatism : -2.38 D @ 9°

• Pachymetry: irregular pattern• TCP = 585µm.

• Irregular posterior surface by BFTA map • Corneal edema

• Anterior Є2 of 0.64• Posterior Є2 of 0.76

• Vertical trefoil = 0.22 µm, • Horizontal coma = -0.36 µm• Horiz. quatrefoil=-0.33 µm• SA = -0.03 µm.

• Courtesy of Schmul Levertovski, MD, Israel.

Custom Selection of IOLCustom Selection of IOL

• Qualitative exam of both surfaces by curvature and by BFS, BFTA elevation maps

• Quantitative assessment of aspheric change of curvature on BFTA elevation maps

• Kranemann-Arce index of asymmetry on BFTA: (difference between highest yellow and lowest blue zones)

• Irregular aspheric curvature change: larger trefoil and/or quatrefoil (several yellow and blue zones)

Paciente femenino, Paciente femenino, 79 años79 añosAV c/c OD 20/40 OI 20/50AV c/c OD 20/40 OI 20/50Córneas transparentesCórneas transparentesCataratas AO + OI; AO + OI; PIO AO: 19 mm HgPIO AO: 19 mm HgRetina:Periferia y polo posterior OkRetina:Periferia y polo posterior Ok

Biometría: Biometría: AL=24.5.mmAL=24.5.mmDesea LIO Premium multifocalDesea LIO Premium multifocal Galilei Sim K = 44.40 @116°– 45.33 @26°Galilei Sim K = 44.40 @116°– 45.33 @26°TCP (ray-tracing) 4 mm Avg= 44.64 DTCP (ray-tracing) 4 mm Avg= 44.64 DCCT= 616 µmCCT= 616 µmЄЄ22 anterior=0.09; anterior=0.09; ЄЄ22 posterior =-0.01 posterior =-0.01

WF Córnea: WF Córnea: Coma V.= -0.75 µm; Coma H.=0.19 µm Coma V.= -0.75 µm; Coma H.=0.19 µm Trefoil H.=0.56 µm; Trefoil H.=0.56 µm; Aberración Esf.=0.34 µm Aberración Esf.=0.34 µm Pupila=2.27 mm; Limbo H.=11.20 mmPupila=2.27 mm; Limbo H.=11.20 mm

ACD (endo)=2.19 mm; ACD (endo)=2.19 mm; ACD (epit)=2.81 mmACD (epit)=2.81 mm; ; Vol (8mm)=74.5 mmVol (8mm)=74.5 mm22

Asimetria Vertical ant y post de curvatura

dentro de rango normal

Curvatura y BFS: Astigmatismo

contra la regla ant y post

K post= -6.19 @ 114° / -6.27 @ 24°Curvatura, BFS y BFTA ant y

post con patrones no congruentes

BFS anterior: Patrón en puente verticalBFS posterior: Patrón indeterminado

BFTA: Asimetría irregular de asfericidad

Opciones de LIOOpciones de LIO

Desea LIO Premium multifocal !!

1.- Esférica 2.- Asférica negativa monofocal 3.- Asférica negativa multifocal 4.- Asférica neutra monofocal 5.- Asférica neutra multifocal 6.- Asférica neutra monofocal + multifocal en

surco

Microscopia Especular: 2000 celSigno del camello: Pico endotelial

anormalÁngulo grado 3 Shaffer=> Edema de córnea

Opciones de LIOOpciones de LIODesea LIO Premium multifocal !!

1.- Esférica 2.- Asférica negativa monofocal 3.- Asférica negativa multifocal 4.- Asférica neutra monofocal 5.- Asférica neutra multifocal 6.- Asférica neutra monofocal + multifocal en surco