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Evolution of Diffractive MultifocalEvolution of Diffractive MultifocalIntraocular LensesIntraocular Lenses
Wavefront CongressWavefront CongressFebruary 24, 2007February 24, 2007
Michael J. Simpson, Ph.D.Michael J. Simpson, Ph.D.Alcon Research, Ltd., Fort Worth, TexasAlcon Research, Ltd., Fort Worth, Texas
Presentation OverviewPresentation Overview Multifocal Multifocal IOLsIOLs
two lens powerstwo lens powers
Early Diffractive multifocal IOLEarly Diffractive multifocal IOL full-optic, equal energyfull-optic, equal energy rigid, meniscus, strong loops (it is not just the optics)rigid, meniscus, strong loops (it is not just the optics)
Full-optic, equal energy, foldableFull-optic, equal energy, foldable Full-optic, unequal energy, foldableFull-optic, unequal energy, foldable ReSTOR Apodized diffractiveReSTOR Apodized diffractive DiscussionDiscussion
Multifocal Multifocal IOLsIOLs
Two primary lens powersTwo primary lens powersdistancenear
Base power for distance visionBase power for distance vision
““AddAdd”” power for near vision power for near vision
20 Years of Multifocal 20 Years of Multifocal IOLsIOLs (1987-2007) (1987-2007)
e.g.IOLABNuVue
e.g. StorzTrueVista
e.g.AMOArray/ReZoom
n=near d nd
ndnd
2 zones 3 zones 5 zones
d
Zonal Refractive: Each zone has either distance or near power
d=distance
12 diffractive zones.e.g. Alcon AcrySofReSTOR
Apodized Diffractive: Central diffractive blends into outer distance power
~ 30 diffractive zones.e.g. 3M 815LE,Pharmacia 811 E,AMO Tecnis 9001
Diffractive: Light goes into both distance and near powers from all zones
Diffractive Multifocal LensesDiffractive Multifocal Lenses Physical geometry is very importantPhysical geometry is very important
Place zone boundary where optical distancePlace zone boundary where optical distanceto image increases by 1 wavelengthto image increases by 1 wavelength
Create optical jump in phase at boundaryCreate optical jump in phase at boundary Zones shaped to direct lightZones shaped to direct light Light from all zones goes to both imagesLight from all zones goes to both images Adjacent zones have Adjacent zones have
similar effectssimilar effects
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1 2 3 4 5Pupil Diameter (mm)
Rel
ativ
e En
ergy
Near
Distance
Full-optic Equal-Energy Diffractive IOLFull-optic Equal-Energy Diffractive IOLTheoretical Energy Balance at 550 nmTheoretical Energy Balance at 550 nm
81% theoreticalmaximum
constant diffractive steps heights across entire lens
distance and near ~ 41 % for all pupils
additional energy goes to higher diffraction orders
steps only ~ 1-2 microns
• Rigid PMMA lenses•6mm diameter, large incision
• Meniscus optic shape• meniscus lenses no longer used
•Closed-loop and long haptics• large force on capsule
Full Optic Equal-Energy Diffractive IOLFull Optic Equal-Energy Diffractive IOLInitial 3M Diffractive IOL, 1988Initial 3M Diffractive IOL, 1988
Improvements to Improvements to IOLsIOLs and surgery : and surgery :The lens platform is also importantThe lens platform is also important
Foldable lenses have replaced rigid lensesFoldable lenses have replaced rigid lenses smaller incisions, lower aberrationssmaller incisions, lower aberrations
PhacoemulsificationPhacoemulsification and capsular bag implantation and capsular bag implantation IOLsIOLs stable in the bag stable in the bag
Gentle Gentle hapticshaptics strong strong hapticshaptics of early lenses displaced the optic of early lenses displaced the optic
Reduced PCO (Posterior Capsular Reduced PCO (Posterior Capsular OpacificationOpacification)) improved contrastimproved contrast
Aberration control (shape factor and Aberration control (shape factor and asphericityasphericity)) reduced spherical aberrationreduced spherical aberration improved large-pupil contrastimproved large-pupil contrast
• Biconvex 3M IOLs, rigid PMMA• Biconvex Pharmacia 811E, rigid PMMA• Biconvex AMO Tecnis Z9001, foldable silicone, aspheric
More recent Full Optic Equal-Energy Diffractive More recent Full Optic Equal-Energy Diffractive IOLsIOLsLenses with published clinical dataLenses with published clinical data
Full Optic Full Optic UnUnequal-Energy Diffractive equal-Energy Diffractive IOLsIOLs
Changing the step heights changes the energyChanging the step heights changes the energy lower steps send more light to distancelower steps send more light to distance higher steps send more light to nearhigher steps send more light to near all zones have the same optical effectall zones have the same optical effect
““Distance dominantDistance dominant”” or or ““Near dominantNear dominant””
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Pupil Diameter (mm)
Frac
tion
of E
nerg
y to
Dis
tanc
e (d
) or N
ear (
n) Equal dEqual n70/30 d70/30 n
Full Optic Full Optic UnUnequal Energy Diffractive equal Energy Diffractive IOLsIOLs
shorter steps send less light to near
taller steps send more light to near
Diffractive step heights control the energyDiffractive step heights control the energy Total energy for the two powers typically ~81%Total energy for the two powers typically ~81%
distance energy for shorter steps; near energy for taller steps
near energy for shorter steps; distance energy for taller steps
Full Optic Full Optic UnUnequal Energy Diffractive equal Energy Diffractive IOLsIOLs
Energy balance sometimes given just for primaryEnergy balance sometimes given just for primarypowerspowers portion of total energy not always givenportion of total energy not always given e.g. 70%:30% e.g. 70%:30% distance:neardistance:near energy, energy,
•• actually 57% distance, 25% near at design wavelengthactually 57% distance, 25% near at design wavelength
IOL examples are IOL examples are AdatomedAdatomed, , Acri.TwinAcri.Twin, and, andAcri.LisaAcri.Lisa IOLsIOLs foldable diffractive lensesfoldable diffractive lenses biconvexbiconvex asphericaspheric sloped diffractive steps for sloped diffractive steps for Acri.LisaAcri.Lisa
Limited published clinical dataLimited published clinical data
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ergy
Near
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Limitations of Full Optic Diffractive Limitations of Full Optic Diffractive IOLsIOLs
Near vision rarely used for large pupilactivities, and the near componentcreates a halo effect for distance visionwith large pupils
Most large pupil activitiesinvolve distance vision
The maximum energy in thetwo images is about 81%
Theoretical relative energy at design wavelength between distance and near
Apodized Diffractive Surface and Energy BalanceApodized Diffractive Surface and Energy Balance
ReSTOR use of Apodization toReSTOR use of Apodization toControl Defocused LightControl Defocused Light
The ReSTOR Apodized Diffractive OpticThe ReSTOR Apodized Diffractive Optic
Step heightsdecreaseperipherallyfrom 1.3 – 0.2microns
Central 3.6 mmapodized diffractive
structure
Outer refractive region
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Frac
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of E
nerg
y to
Dis
tanc
e (d
) or N
ear (
n)
Equal dEqual n70/30 d70/30 nReSTOR dReSTOR n
Energy Balance ComparisonEnergy Balance Comparison
apodized diffractive
equal energy diffractive
unequal energy diffractive
Apodized Diffractive DesignApodized Diffractive Design
Diffractive zones are in same locations as for full-Diffractive zones are in same locations as for full-optic diffractive IOLoptic diffractive IOL zone location determined by zone location determined by ““AddAdd”” power power
Apodized diffractive structure blends into peripheralApodized diffractive structure blends into peripheralrefractive regionrefractive region
Matches optical properties to visual needsMatches optical properties to visual needs Reduces nighttime visual phenomenaReduces nighttime visual phenomena Increases overall percentage of light usedIncreases overall percentage of light used
Apodized Diffractive IOL Lens PlatformApodized Diffractive IOL Lens Platform
•• Proven AcrySof materialProven AcrySof material•• Single-Piece designSingle-Piece design•• Slow, controlled, unfoldingSlow, controlled, unfolding•• Easy to insertEasy to insert
~ 25 Million AcrySof lenses implanted
Large Binocular Depth of FocusLarge Binocular Depth of Focus
n= 27
n= 34
excellent distance vision excellent near vision
n=22 ReSTOR, n=17 monofocal
80
17
3
0102030405060708090
100
% o
f S
ub
ject
s
Never Sometimes Always
Overall Spectacle Wear
ReSTOR (N=339)
High level of Spectacle IndependenceHigh level of Spectacle Independence
Modest Visual DisturbancesModest Visual Disturbances120-180 Days Post-Operative120-180 Days Post-Operative
Night Vision Problems
Halos Glare
ReSTOR®
N=457
MonofocalControlN=156
None, Mild Moderate Severe
9%4%
87% 76%
5%19%
4%2%
94%
2%
97%
1%7%2%
91%
21% 5%
74%
9%4%
87% 76%
5%19%
4%2%
94%
2%
97%
1%7%2%
91%
21% 5%
74%
Conclusion:Conclusion: Diffractive Multifocal Diffractive Multifocal IOLsIOLs
Diffraction divides light between two powersDiffraction divides light between two powers Diffractive step heights control the energy balanceDiffractive step heights control the energy balance Apodized diffractive IOL has gradual change inApodized diffractive IOL has gradual change in
step heightsstep heights central distance/near vision regioncentral distance/near vision region outer outer ““refractiverefractive”” distance vision region distance vision region allocates appropriate light energy according to activityallocates appropriate light energy according to activity
and light levelsand light levels designed to minimize photic issuesdesigned to minimize photic issues high level of spectacle independencehigh level of spectacle independence
Thank YouThank You
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