1

Surgically induced aberrations and optical performance

Susana Marcos, Ph.D.Instituto de Optica, CSIC

Wavefront Sensing Meeting. San Francisco. Feb.2003 Aberrations &Optical performance

Corneal Refractive surgery(LASIK)

Where does the optical degradation arise from?

Cataract surgery

Aberrations

Simpler case: defocus (myopia)

.

The eye suffers from aberrations of higherorder than defocus

Aberrations

Aberrated wavefront spherical wavefront

WAVE ABERRATION

What is the wave aberrationWhat is the wave aberration??Wave aberration:phase distortions at thepupil plane

topographic map

? m

2

???

??

??),(1

'W

Rx

p

???

???? ),(1' W

Ry

p

(?0,? 0)

(? x’,? y’)(?0,? 0)

Mathematical expressionMathematical expression

The deviations at the plane of the retina are proportional to the derivatives of the wave aberration

ZernikeZernike Polynomial expansionPolynomial expansion

= Z2

+ Z3 + Z3 + Z3 + ...

+ Z4 +...+ Z7 + Z7

+2 + Z2-2

3 1 -1

0 -5 -7

Root mean square Root mean square wavefrontwavefront errorerror::

— mean?2

RMS =RMS =

Optical quality metricsOptical quality metrics Wavefront aberration

Image of a point (PSF)

Modulation Transfer (MTF)

MethodsMethodsTotal aberrations:

LRTCorneal aberrations:

Topographer +

Custom software

Ocular biometryIOL master(OCT +Slit lamp)

2nd 2nd generationgeneration LRTLRT

Pupil Pupil monitoringmonitoring

FixationFixationchannelchannel

3

Aberratedwavefront

Laser Ray Tracing: Basic ConceptLaser Ray Tracing: Basic Concept

-150 -100 -50 0 50

-100

-50

0

Spot diagram Pupil Sampling

Data collectionData collection

Elevation map

Corneal topography

Ray Tracing

Corneal aberrations

Corneal aberrationsCorneal aberrations

Barbero et al. J.Refrt. Surg (2002)

Zernike Coefficient #

Ze

rnik

e A

mp

litu

de(

µm

)

Total CoefficientsCorneal Coefficients

Patient A: OD

0 5 10 15 20 25 30 35

-2.5

-1.5

-0.5

0.5

1.5

-3.0

-2.0

-1.0

0.0

1.0

Zernike Coefficient #

Ze

rnik

e A

mp

litu

de(

?m

)

Patient A: OI

0 5 10 15 20 25 30 35

-2.5

-1.5

-0.5

0.5

1.5

-3.0

-2.0

-1.0

0.0

1.0

ODTotal Corneal

OSTotal Corneal

KeratoconusKeratoconusBarbero, Marcos, Merayo, Moreno. J. Refract. Surg. (2002)

Total CoefficientsCorneal Coefficients

Zernike Coefficient #0 5 10 15 20 25 30 35-1.5

-0.5

0.5

-1.0

0.0

Ze

rnik

e A

mp

litu

de(

µm

)

Patient B: OD

Corneal

Total

AphakicAphakic Barbero, Marcos & Merayo. J. Cat. Refract. Surg. (2002)

= +

Total Corneal Internal

Aberrations and Cataract Surgery

4

?9 eyes from 7 subjects ?mean age: 70.58 ± 8.96?Measurements at least 2 months post-surgery?6 eyes also before surgery

?Phacoemulsification: 4.1 mm superior incision (no suture)?Spherical IOLs?Powers from 0 to 26 D.

Patients Patients ((cataract surgerycataract surgery))

Eye #1-IOL 0 D

Total Corneal Internal

Eye #4-IOL 21 Dp

Eye #4-IOL 23 Dp

Eye #9-IOL 26 D

Total Corneal Internal

Total, Total, cornealcorneal & & internal aberrationsinternal aberrationsPOST CATARACT POST CATARACT surgerysurgery

0 D 14 D 16.5 D 21 D 23 D

23 D 23 D 25.5 D 26 D

IOL IOL wave aberrations wave aberrations in vivoin vivo

? m

Barbero , Marcos, & Jimenez-Alfaro , JOSA A (2003)

00,10,20,3

0,40,5

0,60,70,80,9

Total Corneal Internal

RM

S 3

rd&

Hig

her

(mic

rons

)

Pre

Post

Young

ComparisonComparison total total aberrations aberrations PRE/POST/YOUNG control PRE/POST/YOUNG control group group

Barbero , Marcos, & Jimenez-Alfaro , JOSA A (2003)

Pre-cataract surgery Post-cataract surgery Young control

Age= 67RMS=0.63 ? m

Age= 68RMS=0.85 ? m

Age= 28RMS=0.15 ? m

? m

Why the aberrations of pseudophakic Why the aberrations of pseudophakic patientspatients are are higher than those of young higher than those of young eyeseyes?? ?Increase of corneal aberrations with age, and

increase of corneal aberrations by incision

?Aberrations of the IOL

?Tilt/decentrations of IOL

?No balance internal/corneal aberrations

Various reasonsVarious reasons::

5

Corneal aberrationsCorneal aberrationsIncrease of corneal aberrations with age

Oshika et al.1999Guirao et al. 2000

0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

0,8

Eye #2 Eye #11 Eye #14

RM

S 3

rd &

Hig

her

(mic

rons

)

PRE POST

Slight increase of corneal aberrationswith surgery

1 mm 0.8 mm

Camara objetive Methachrylate

wall IOL

5 mm

Effective aperture: 4.22 mm

Nikkor camera objective Water cell

Movingartificial retinaIOL

MeasuringMeasuring IOL IOL aberrationsaberrations in in vitrovitro

IOL IOL wave aberrations wave aberrations in in vitrovitro

0 D 12 D 23 D16 D

Barbero , Marcos, & Jimenez-Alfaro , JOSA A (2003)

Ideal cornea(for in vitro measurements comparisons)

Or individual cornea(for in vivo measurements comparisons)

Predicted aberrations of thePredicted aberrations of the IOLIOL

0

0,1

0,2

0,3

0,4

0,5

0,6

3rd&Higher 3rd 4rd&Higher Astigm

RM

S (

mic

ron

s) In vivo

Ex vivo

IOL IOL AberrationsAberrations: in vivo : in vivo and and in in vitrovitro Spherical aberration of theSpherical aberration of the IOLIOL

Positive spherical aberration!!

0 5 10 15 20 25 30IOLPower (D)

-0.2

-0.1

0.0

0.1

0.2

0.3

0.4

0.5

In vivo

In vitro

Simulation

sphe

rica

l abe

rrat

ion

(mic

rons

)

6

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

Eye #7 Eye #8 Eye #9 Eye #10 Eye #11 Eye #14 Eye #15

In vivo

Simulations

Spherical aberrationSpherical aberration: in vivo/: in vivo/simulatedsimulated

sphe

rica

l abe

rrat

ion

(mic

rons

)

0

0.5

1

1.5

2

3rd&higher 3rd 4rd&higher 4rd

RM

S (m

icro

ns)

In vivoIn vitro

Third order aberrationsThird order aberrations: : TiltsTilts

0 deg +4 deg

0.24 ? m 0.48 ? m

In vitro on/off axis

-0.6 -0.4 -0.2 0.0 0.2 0.4 0.6Decentration (mm)

0.00

0.02

0.04

0.06

0.08

0.10

0.12

3rd

ord

er R

MS

(mic

ron

s)

2-deg tilt (x axis)

Horizontal decentration

Vertical decentration

-4 -2 0 2 4Tilt (deg)

0.00

0.05

0.10

0.15

0.20

3rd

ord

er

RM

S (

mic

rons

)

horizontal tilt

vertical tilt

0.5-mm horizontal decentration

Third order aberrationsThird order aberrations: : Simulated Simulated TiltsTilts & & decentrationsdecentrations

00,05

0,10,15

0,20,25

0,30,35

Post YoungRM

S s

ph

eric

al a

ber

rati

on

TotalCornealInternal

CornealCorneal / / Internal aberrationInternal aberration balancebalance

Wavefront aberration

Image of a point (PSF)

Modulation Transfer (MTF)

?In vitro MTF measurements

? In vivo double-pass MTF measurements

Optical performance Optical performance in in terms of terms of MTFMTF

7

0 10 20 30 40 50Spatial Frequency (c/deg)

0.1

1.0

MTF

In vitro (Acrysof)

Simulation (Acrysof)

Oshika et al. (Acrysof)

Norrby et al. (PMMA)

IOL’s MTF (in IOL’s MTF (in vitro and fromvitro and from designdesign))

? = 3 mm0 10 20 30 40 50 60 70 80 90

Spatial Frequency (c/deg)

0.0

0.1

1.0

MTF

Young eyes

Post surgery eyes

Guirao double-pass

Artal double-pass

Ocular MTFOcular MTF

? = 4 mm

ConclusionConclusion

IOLs elliminate the degradation IOLs elliminate the degradation produced produced by by scatteringscattering, , but but do do not not restore optical quality to young eyes’ restore optical quality to young eyes’ valuesvalues........

THERE IS ROOM FOR IMPROVEMENTTHERE IS ROOM FOR IMPROVEMENT

Age= 23.2RMS= 0.66 ? m

Age= 40.1RMS= 0.87 ? m

Age= 50.2RMS= 0.80 ? m

Age= 62,9RMS= 1.04 ? m

? mNormal aging

Young control

Age= 28RMS=0.15 ? m

? = 7.3 mm

Post-cataract surgery

Age= 68RMS=0.85 ? m

? m

? = 5 mm

McLellan, Marcos & Burns, IOVS, 2000

Optical vs visual performanve

spatial frequency (c/deg)0 1 0 20 30 40 50 60 70

0.0

0.2

0.4

0.6

0.8

1.0

MT

F

Optical vs visual performanve

spatial frequency (c/deg)0 1 0 20 30 40 50 60 70

0.0

0.2

0.4

0.6

0.8

1.0

MT

F

spatial frequency (c/deg)0 1 0 2 0 30 40 50 60 70

0.0

0.2

0.4

0.6

0.8

1.0

CSF

8

What is the CSF?

spatial frequency (c/deg)

CSF

2 4 6 8 210spatial frequency (c/deg)

0.0

0.5

1.0

1.5

2.0

2.5

Lo

g C

ontr

ast S

ensi

tiv

ity

Visual Visual performance with IOLsperformance with IOLs

Young eyesOld normal eyesEyes with IOL’s

Adapted from Navarro, Ferro, Artal & Miranda, 1993

Potential solution

Aspheric IOLsAspheric IOLsWith negative spherical aberrationWith negative spherical aberration, , ideally ideally

matching the matching the individual corneaindividual cornea

Drawbacks

Tilts and decentrations Tilts and decentrations more more detelerious than detelerious than for spheric IOLs for spheric IOLs ((AtchisonAtchison, 1989), 1989)

Presence of aberrations becomes attenuated by...

Smaller pupils

Increased depth-of-field (i.e. Multifocality)

Will the benefits of aspheric IOLs exceed their potential drawbacks?

Is an aberration-free eye really needed in an eye without accommodative response?

Other questions

Should we aim toward a customized intraocular(cataract) surgery?

http://patient. isrs.org

Moreno-Barriuso et al. IOVS; Marcos 2001

Optical aberrations and standard LASIK refractive surgery

9

www.lasersite .com

Patients Patients ((myopicmyopic LASIK)LASIK)

?22 eyes from 12 subjects ?mean age: 28?5?Spherical equivalent: -2.5 thru –13 D?No ocular or retinal condition?Measurements <1 mo. before and >1 mo. after surgery

?Flying spot Technolas 217-C (B&L surgical)?Hansatome microkeratome?Optical zone: 6 mm. Transition zone: 9 mm

gacod

CornealTotal

Pre-LASIK

Post-LASIK

RMS=0.83 ? m RMS=0.87 ? m

RMS=2.67? m RMS=2.66 ? m

Marcos et al. IOVS (2001)

ahcoi

CornealTotal

Pre-LASIK

Post-LASIK

RMS=0.54 ? m RMS=0.35 ? m

RMS=1.95 ? m RMS=1.93 ? m

Marcos et al. IOVS (2001)ahcod

CornealTotal

Pre-LASIK

Post-LASIK

RMS=0.54 ? m RMS=0.61 ? m

RMS=1.40 ? m RMS=1.49 ? m

mmaoi

CornealTotal

Pre-LASIK

Post-LASIK

RMS=0.74 ? m RMS=0.71 ? m

RMS=1.87 ? m RMS=2.36 ? m

Marcos et al. IOVS (2001)

3rd 3rd and higher orderand higher order

0

0.5

1

1.5

2

2.5

3

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22

EYE #

RM

S (

?m

)

PRERE--LASIKLASIKPOST-LASIK

Moreno-Barriuso et al. IOVS (2001)

TOTAL TOTAL aberrationsaberrations

10

Average data

00.20.40.60.8

11.21.41.61.8

3rd - 7thorder

3rd order 4rth order 5th &higherorders

n= 22n= 22

3rd-7th

orders3rd

order4th

order5th & higher

orderssphericalaberration

PREPRE--LASIKLASIKPOSTPOST--LASIKLASIK

p=0.003 p=0.0028 p<0.0001 p<0.0001p=0.17** ** ** **

RM

S (?

m)

Moreno-Barriuso et al. IOVS (2001)

-0.5

0

0.5

1

1.5

2

1 2 3 4 5 6 7 8 9 10 11 12 13 14

Tot-pre

Tot-post

Increase of TOTAL Spherical Aberration with LASIK

Spherical aberration

eye #

04Z

? m

Marcos et al. IOVS (2001)

The higher the pre-op spherical error, the largerspherical aberration is induced

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

r = 0.76

14121086420PRE-LASIK SPHERICAL ERROR (D)

PO

ST-

LAS

IK S

PH

ER

ICA

L A

B.(?

m)

-0.5

0

0.5

1

1.5

2

1 2 3 4 5 6 7 8 9 10 11 12 13 14

Corn-pre

Corn-post

Increase of CORNEAL Spherical Aberration with LASIK

Spherical aberration

eye #

04Z

? m

Marcos et al. IOVS (2001)

Why spherical aberration increasesWhy spherical aberration increases??

Q>0

Q=0

Q<0

Because corneal asphericity changes from negative values (prolate cornea) to negative values (oblate cornea). Holladay (1999)

Analytical models provide controversial results:

No approximation

Equation for corneal asphericity after refractive surgeryJ.R. Jimenez et al. J. Refract. Surg. In press

CONCLUSIONS: This equation…. Explains the increased spherical aberration after refractive surgery.

Parabolic approximation

11

Munnerlyn formula simulations vs experimental data Munnerlyn ablation depth

POST corneal height

PRE corneal height

POST experimental -simulated

mmmm

POST CorneaExperimental SimulatedR=8.74

Q=0.35R=8.98Q=-0.075

R=9.04Q=0.54

R=9.19Q=0.14

R=9.68Q=1.82

R=9.40Q=0.026

#5

#6

#14

-2-1012345

-2 -2,8 -3,3 -3,5 -5,4 -6,3 -6,3 -7,3 -7,3 -7,5 -7,5 -8,9 -12Spherical Equivalent (D)

as

ph

eri

cit

y

ChangeChange in in corneal asphericity with corneal asphericity with myopicmyopic LASIKLASIK

Q<0 Q>0

-2-10123

45

-2 -2,8 -3,3 -3,5 -5,4 -6,3 -6,3 -7,3 -7,3 -7,5 -7,5 -8,9 -12

Spherical Equivalent (D)

asp

her

icity

Post-Q (Munnerlyn ) Marcos, Cano & Barbero (2003)

Compared to Munnerlyn algorithmCompared to Munnerlyn algorithm

Pre- QPost- Q

-2

-1

0

1

2

3

4

5

-2 -2.8 -3.3 -3.5 -5.4 -6.3 -6.3 -7.3 -7.3 -7.5 -7.5 -8.9 -12spherical equivalent (D)

asp

her

icit

yChangeChange in in corneal asphericity with corneal asphericity with myopicmyopic LASIKLASIKCompared to Munnerlyn Parabolic approximation Compared to Munnerlyn Parabolic approximation

Pre- QPost- QPost-Q (Parabolic Munnerlyn ) Marcos, Cano & Barbero (2003)

Radial Radial changes of absorbtion efficiencychanges of absorbtion efficiency

?Changes in spot area

?Reflection losses?KoI

K? I

Mrochen & Seiler, 2001Jiménez et al., 2002

Changes in absorbtion

Increased asphericity

Why corneal asphericity increasesWhy corneal asphericity increases??

Does the ablation profile really follow the Munnerlyn equation, or an approximation ?

Is the discrepancy due to biomechanical changes?

Is the ablation profile properly transferred onto the cornea?

CRITICAL FOR CRITICAL FOR CUSTOMIZED/OPTIMIZED CORRECTIONCUSTOMIZED/OPTIMIZED CORRECTION

12

-16.0 -12.0 -8.0 -4.0 0.0pre-op spherical error (D)

-1.0

0.0

1.0

2.0

3.0Corneal

Total

Internal

Indu

ced

Sph

eric

al a

berr

atio

n(?

m)

INDUCED corneal, total & internal aberration

Marcos et al. IOVS (2001)

PRE POST

Can the change of ray convergence on the crystalline lens be the cause of the measured change in internal aberrations?

Explaining the changes in the internal optics

Computer simulation

Internal aberration= Total – Corneal

-16 -12 -8 -4 0Pre-op spherical error (D)

-0.1

0.0

0.1

0.2Simulated Internal POST-PRE

Ind

uce

d in

tern

al

sph

eric

al a

ber

rati

on

(?m

)

Real cornealanterior surface

Model crystalline lens

Simulated total aberrations

Toward positivevalues!

Intraocularpressure

Laserablation

Can be changes in the posterior corneal surfacebe the cause of shift of internal aberrations to negative values?

Explaining the changes in the internal optics

Comparing with scanning slit topography data

Previous studies using Orbscan showed changesin the posterior corneal surface after LASIK

Naroo & Charman (2000)Baek et al. (2001)Bruno et al. (2001)Seitz et al. (2001)

Do those changes in the posterior corneal shapepredict our change in posterior spherical aberration?

Spherical aberrationof posterior cornea inducedby LASIK

Ray Tracing Seitz et al. (2001):Change in central power:

-6.28 D -6.39 DChange in asphericity (P)

0.98 -1.14 -0.103 ? m

This study. Marcos et al. (2001) -0.110 ? m

13

Most changes in the spherical aberration of the internal optics with LASIK seem to be due to the posterior corneal surface

-16 -12 -8 -4 0pre-op spherical error (D)

-1.5

-1.0

-0.5

0.0

0.5

PO

ST-

PR

E in

tern

al

sphe

rica

l abe

rrat

ion

(D)

Experimental

Convergence

The role of pre-LASIK internal optics

pre

post

Total Corneal Internal

amaodMarcos et al. IOVS (2001)

Spherical aberrationSpherical aberration in in myopic eyesmyopic eyes

-0.5

-0.3-0.1

0.10.30.5

0.70.9

1.11.3

1.5

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

-0.5

-0.3

-0.1

0.1

0.3

0.5

0.7

0.9

1.1

1.3

1.5

1 2 3 4 5 6 7 8 9 10 11 12 1 3

Low myopes (-0.25 – -4.1 D)

TotalCorneal

Moderate myopes (-4.4 – -7 D)

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1

1 2 3 4 5 6 7 8 9 1 0 11 12 13 1 4 15 16

High myopes (-7.1 – -15D)

sph.

ab

erra

tio

n c

oef

f. (?

m)

Marcos et al. OSA 2001

-16 -12 -8 -4 0spherical error (D)

-1.0

0.0

1.0

co

eff 1

2 (m

icro

ns

)

Total

Internal

Corneal

Total

Corneal

Internal

(p=0.95)

(p=0.001)

(p=0.009)

Marcos et al. OSA 2001

Spherical aberrationSpherical aberration in in myopic eyesmyopic eyes

AberrationsAberrations in in myopic eyesmyopic eyes

-0.7 D -6.5 D -11 D

RMS=0.39 ? m RMS=0.63 ? m RMS=0.98 ? m

0 4 8 12Spherical error (D)

0

RM

S 3

rdor

der

and

high

er (?

m)

0 4 8 12Spherical error (D)

0

1

2

RM

S 3

rd o

rder

and

hig

her

(mm

)

4

-3

2

0-1.5

? m

Marcos et al. 2000

n=53

r= 0.42 p=0.0014

Hyperopic LASIK Refractive Surgery

The central cornea is made steeper than the periphery, by removing tissue around the central area

14

Patients Patients ((hyperopichyperopic LASIK)LASIK)

?13 eyes from 7 subjects ?mean age: 32?11?Spherical equivalent: +1.25 thru +3.5 D?No ocular or retinal condition?Measurements <1 mo. before and >1 mo. after surgery

?Flying spot Technolas 217-C (B&L surgical)?Hansatome microkeratome

http://www.lasersite .com

Total Corneal

Pre

Post

RMS= 0.34 ? m

RMS= 0.82 ? mRMS= 1.13 ? m

RMS= 0.63 ? m

cssoi

RMS= 1.00 ? m

RMS= 0.93 ? mRMS= 0.94 ? m

RMS= 0.67 ? m

cssod

Total Corneal

Pre

Post

RMS= 0.52 ? m

RMS= 1.14 ? mRMS= 1.25 ? m

RMS= 0.50 ? m

ifroi

Total Corneal

Pre

Post

RMS= 0.81 ? m

RMS= 1.64 ? mRMS= 1.92 ? m

RMS= 0.70 ? m

cfaoi

Total Corneal

Pre

Post

RMS= 0.75 ? m

RMS= 2.10 ? mRMS= 2.10 ? m

RMS= 0.75 ? m

cfaod

Total Corneal

Pre

Post

15

0

0.2

0.4

0.6

0.8

1

1.2

1 2 3 4 5 6 7 8 9 10 11 12 13

Eye #

RM

S (

?m)

TOTALCORNEAL

AberrationsAberrations in in hyperopic eyeshyperopic eyes

3rd and higher order aberrations

PrePre-- opopLlorente, Marcos, Barbero & Merayo, IOVS (Suppl), 2002

AberrationsAberrations in in hyperopic eyeshyperopic eyes

spherical aberrations

PrePre-- opop

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

1 2 3 4 5 6 7 8 9 10 11 12 13Eye #

Coe

ff.Z 4

0 ( ?m

)

TOTALCORNEAL

Llorente, Marcos, Barbero & Merayo, IOVS (Suppl), 2002

Spherical aberration

20

22

24

26

28

0 1 2 3 4 5 6 7 8|Spherical Error| (D)

Ax

ial

Le

ng

th (

mm

)

Myopes

Hyperopes

MyopesMyopes/ / hyperopichyperopic eyeseyesAxial length

-0.6-0.4-0.2

00.20.4

0 1 2 3 4 5 6 7 8|Spherical Error| (D)

Asp

heri

cit

y

Corneal asphericity

Llorente, Marcos, Barbero & Merayo, IOVS (Suppl), 2002

0

0.5

1

1.5

2

2.5

1 2 3 4 5 6 7 8 9 10 11 12 13Eye #

RM

S (

?m)

PRE-LASIK HPOST-LASIK H

Change ofChange of TOTAL TOTAL aberrations with aberrations with hyperopichyperopic LASIKLASIK

3rd and higher order aberrations

Llorente, Marcos, Barbero & Merayo, IOVS (Suppl), 2002

-1,2-1,0-0,8-0,6-0,4-0,20,00,20,40,60,8

1 2 3 4 5 6 7 8 9 10 11 12 13

RM

S (

m)

PRE-LASIK HPOST-LASIK H

Spherical aberration

Change ofChange of TOTAL TOTAL aberrations with aberrations with hyperopichyperopic LASIKLASIK

Llorente, Marcos, Barbero & Merayo, IOVS (Suppl), 2002

-1,4-1,2-1,0-0,8-0,6-0,4-0,20,00,20,40,60,8

1 2 3 4 5 6 7 8 9 10 11 12 13

Eye #

Coe

ff.

Z40

?????

m?

PRE-LASIK HPOST-LASIK H

Change ofChange of CORNEAL CORNEAL aberrations with aberrations with hyperopichyperopic LASIKLASIK

Spherical aberration

Llorente, Marcos, Barbero & Merayo, IOVS (Suppl), 2002

16

Myopic LASIK

Hyperopic LASIK

Slope= 0,1701R= 0,86

-2-1,5

-1-0,5

00,5

11,5

2

0 2 4 6 8 10 12 14

Corneal

|Pre-LASIK Spherical Error| (D)

Slope= -0,23R= 0,60

-1,5

-1-0,5

00,5

11,5

2

0 2 4 6 8 10 12 14

Total

|Pre-LASIK Spherical Error| (D)

Slope= 0,091R= 0,63

Slope= -0,057R= 0,24

Spherical aberration inducedSpherical aberration induced by LASIKby LASIK

Llorente, Marcos, Barbero & Merayo, IOVS (Suppl), 2002

Indu

ced

sphe

rica

lA

berr

atio

n (?

m)

Indu

ced

sphe

rica

l A

berr

atio

n (?

m)

Comparison with visual performance

Contrast sensitivity MTF horizontal sectionPRE & POST PRE & POST

LASIKLASIK

CSFCSF

Co

ntr

ast

sen

siti

vity

0.0 4.0 8.0 12.0 16.0 20.0spatial frequency(c/deg)

0

40

80

120

Mo

du

lati

on

tra

nsf

er

MTFMTF

0 10 20 30spatial frequency (c/deg)

0.0

0.2

0.4

0.6

0.8

1.0

undilated pupil 3 mm

Area Area = 1.51= 1.51PREPREPRE

POSTPOST Area Area = 1.38= 1.38PREPREPRE

POSTPOSTMarcos. J. Refract. Surg . (2001)

ContrastContrast ratio POST/PREratio POST/PRE

0 10 20 30spatial frequency (c/deg )

0.2

0.4

0.6

0.8

1.0

CSF ratio

MTF ratio

Co

ntr

astr

atio

PR

E/P

OS

TAverage 22 eyes

Marcos. J. Refract. Surg . (2001)

Total and corneal aberrometry provide:?Detailed evaluation of correction procedures?Clues for improvent and customization

• LASIK ablation algorithms should be optimized to avoid aberration induction.

• IOL lenses design could improve to achieve better corneal/internal balance

Publicationshttp://www.io.csic.es/susana/susana.htm

17

Collaborative Clinical Sites

Instituto de Oftalmobiologia Aplicada, U. Valladolid(Jesus Merayo)

Fundacion Jimenez Diaz, Madrid(Ignacio Jimenez-Alfaro)

Carlos Dorronsoro

DanielCano

Elena Garcia de la Cera

SergioBarbero

LourdesLlorente

Funding

Grant CAM08.7/0010.1/2000Madrid Regional Government

Carl Zeiss, S.A., Spain

, Atlanta, GA

Grant BFM2002-02638Spanish Ministry of Science and Technology

Alcon Research Labs