Wavefront-guided Photorefractive Keratectomy to Correct Ametopia following ReSTOR Implantation

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Wavefront-guided Photorefractive Keratectomy to
Correct Ametopia following ReSTOR Implantation

• Irene C. Kuo, MD
• Associate Professor of Ophthalmology
• Wilmer Eye Institute
• I have no financial interests research supported
  by an unrestricted grant from Research to Prevent
  Blindness, NY, NY

ASCRS 2009, San Francisco, P-191A
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Co-authors

• Elliott Myrowitz, OD
• Oliver Schein, MD, MPH, MBA
• Roy S. Chuck, MD, PhD (consultant for Advanced
  Medical Optics, Inc., and Alcon Laboratories,
  Inc.)

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Introduction

• expectations of refractive outcomes after
  cataract surgery are increasing.
• ametropia can still occur with multifocal lens
  implantation despite advanced surgical techniques
  and sophisticated methods to predict intraocular
  lens power.

Kuo , ASCRS 2009
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Introduction

• few reports of excimer laser surgery to correct
  residual refractive error in patients implanted
  with multifocal lenses
• questions about accuracy of wavefront acquisition
  in multifocal lenses, both diffractive and
  refractive types

Kuo , ASCRS 2009
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ReSTOR lens apodized diffractive, refractive IOL
Two primary focal points--distance and near
(approx 3.2 D add power in spectacle plane). 12
diffractive discontinuities (steps) in the
anterior surface of the cast-molded acrylic optic
provide the diffractive add power. The steps
cover the central 3.6 mm diameter of the IOL.
The optic from 3.6 mm to the 6.0 mm edge is
comprised of a refractive surface dedicated to
distance vision. 2 mm pupil, 41 distance, 41
near, 18 to higher diffractive orders (with
permission from Davison JA, Simpson MJ. History
and development of the apodized diffractive
intraocular lens. J Cataract Refract Surg
200632849-585).
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Methods

• IRB-approved protocol for refractive patients
• thorough preoperative evaluation
• detailed medical, ocular, social history
• uncorrected and best corrected visual acuity
• manifest refraction , cycloplegic refraction
• corneal topography, pachymetry
• slit-lamp examination, pupillary exam, Schirmer
  testing, dilated exam

Kuo, ASCRS 2009
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Methods

• Orbscan (Bausch and Lomb)
• CustomVue Wavescan (Advanced Medical Optics)
• three or more measurements are obtained with
  undilated pupil 5 mm pupil or larger needed for
  wavescan capture
• measurement where wavefront sphere best matches
  manifest sphere is chosen for treatment
• physician adjustments to sphere are performed
  where needed to improve match between manifest
  and wavefront sphere

Kuo, ASCRS 2009
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Methods

• VISX STAR S4 (Advanced Medical Optics) was used
  in all cases
• eye tracker and iris registration were engaged in
  all eyes
• off-label use of VISX laser in setting of
  pseudophakia was discussed with each patient

Kuo, ASCRS 2009
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Case

• 78-year-old man with bilateral cataracts
• Preoperative Ks 40.27 x 42.99 D in OS at 169
  degrees by IOL Master
• November 2006 uncomplicated cataract extraction
  OS, with 19.5 D ReSTOR SN6AD3 (4 diopter add in
  IOL plane) and limbal relaxing incisions
• YAG laser capsulotomy in June 2007
• August 2007 UCVA was 20/40 and BCVA was 20/30
  with manifest refraction of -1.25 2.00 x
  175wavefront PRK

Kuo, ASCRS 2009
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Case

• corneal pachymetry was 580 microns. Keratometry
  was 41.25 x 42.75 D at 175 by Orbscan
• CustomVue Wavescan showed an RMS of 0.43 µm
• patient underwent wavefront-guided PRK in OS with
  goal of postoperative emmetropia
• wavefront data from a 5.25 mm pupil was used.
  Physician adjustment of -0.75 diopters was
  incorporated in treatment

Kuo, ASCRS 2009
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Kuo, ASCRS 2009
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Kuo, ASCRS 2009
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Results
Post-CE-IOL and pre-PRK Post-CE-IOL and pre-PRK Post-CE-IOL and pre-PRK Post-PRK Post-PRK Post-PRK Post-PRK Post-PRK Post-PRK
UCVA MR, BCVA near 1-2 months 1-2 months 3-6 months 3-6 months 7-10 months 16 months 7-10 months 16 months
UCVA MR, BCVA near UCVA MR, BCVA UCVA MR, BCVA, Near UCVA MR, BCVA, Near
Case 1 OS 20/50 plano1.25x020 20/20 J6 20/25 -0.500.75x145, 20/25 20/25 -0.25, 20/25, J3 20/20 Plano, 20/20, J1
Case 2 OS OD 20/40 20/40 -1.252.00x175 20/30 -0.251.50x035, 20/30 J4 J5 20/40 20/40 -0.250.25x040, 20/40 -0.750.50x100 20/30 20/25 20/30 -0.25, 20/25, J3 -0.250.50x110 20/30 J2 20/25 20/25 Plano, 20/25, J3 20/25 -0.25 J2 0.250.50x090 20/25, J2
Visual acuity of eyes with ReSTOR lens before and
after PRK. CE-IOLcataract extraction with
ReSTOR implantation, UCVAuncorrected Snellen
visual acuity, BCVAbest-corrected Snellen visual
acuity, MRmanifest refraction, JJaeger. All
manifest refractions are in diopters.
Kuo, ASCRS 2009
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Hartmann-Shack Aberrometer
With permission from AMO, Inc.
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Hartmann-Shack Aberrometer
Each spot is analyzed as to how the light is
traveling in that part of the eye
Each Spot or lenslet lets in light
WaveScan software calculates the wavefront map
and generates a wavefront treatment for the laser
to follow
240 points in a 7 mm pupil
With permission from AMO, Inc.
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Why wavefront-guided treatment?

• seems appropriate to correct refractive error
  after implantation of an aspheric multifocal lens
• offers iris registration
• compensates for cyclotorsion and pupil centroid
  shift, thus correcting astigmatism more precisely
  than conventional treatment

Kuo, ASCRS 2009
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Role of excimer laser after multifocal lens
implantation

• unavailability of toric multifocal lenses
• refractive surprises
• range of lens powers for the ReSTOR lenses is
  smaller than range for monofocal lenses
• any residual refractive error after multifocal
  lens implantation will affect vision (and
  contrast sensitivity) at all distances

Kuo, ASCRS 2009
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Drawbacks of H-S sensor with multifocal IOL

• diffractive discontinuities in lens may result in
  locally distorted wavefronts
• spatial distribution of stray centroids (just
  inside or outside pixel subarray of
  charge-coupled device) may be hard to predict
• scattering incurred by discrete junctions between
  diffractive zones
• may lead to overestimation of the optical quality
  of eyes with diffractive multifocal IOLS

Kuo, ASCRS 2009
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Drawbacks of H-S sensor with multifocal IOL

• concentric zones in ReSTOR vs. square microlens
  array may lead to inaccurate reconstruction of
  wavefront

Kuo, ASCRS 2009
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Drawbacks of H-S sensor

• Perhaps the findings from our three cases will
  not be true with larger refractive errors and/or
  with lens tilt/decentration
• tilt/decentration may be more deleterious in
  aspheric than in spheric lenses
• size of capsulorhexis and clarity of posterior
  capsule may also interfere with good wavefront
  capture

Kuo, ASCRS 2009
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Why H-S data may still be acceptable

• At the wavelength used, the aberrometer may be
  unaffected by the diffractive effect of the
  ReSTOR lens
• the higher the wavelength used in the wavefront
  sensor, the lower the diffractive efficiency, and
  the higher the add power

Kuo, ASCRS 2009
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Why H-S data may still be acceptable

• the H-S aberrometers seem more likely to produce
  wavefront results corresponding to the wavefront
  produced by the distance power of a diffractive
  IOL
• Hence, the relative lack of doubling of spots
  in H-S images in eyes with the ReSTOR

Kuo, ASCRS 2009
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Conclusions

• It is possible to obtain good quality wavefront
  data in patients with ReSTOR lens and to use such
  data to design wavefront-guided treatment to
  maximize uncorrected distance and near visual
  acuities after ReSTOR
• reproducible, well-focused, properly aligned
  image
• wavefront and manifest refractions correlate
• Ortiz et al confirmed using another H-S system

Kuo, ASCRS 2009
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Conclusions

• It is possible to mix and match platformsone
  companys IOL and another companys
  wavefont-guided laser

Kuo, ASCRS 2009
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Conclusions

• in our cases, PRK was chosen over laser in-situ
  keratomileusis (LASIK) because of low refractive
  error and possibility that LASIK flap might
  induce more aberrations
• However, perhaps not all patients with multifocal
  IOLs will qualify for wavefront-guided excimer
  laser treatment
• type of IOL, amount of refractive error , corneal
  topography, pachymetry

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Conclusions

• The three eyes in our series had good quality
  wavescans which were used for wavefront-guided
  PRK, with subsequent improvement of UCVA and in
  one case, BCVA
• delay in achieving best UCVA and BCVA
• results of (older) patients undergoing
  conventional laser surgery to correct
  post-cataract surgery ametropia vs. patients who
  have not had CE-IOL

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References

• Charman WN, Montés-Micó R, Radhakrishnan H.
  Problems in the measurement of wavefront
  aberration for eyes implanted with diffractive
  bifocal and multifocal intraocular lenses. J
  Refract Surg. 2008 24(3)280-286.
• Davison JA, Simpson MJ. History and development
  of the apodized diffractive intraocular lens. J
  Cataract Refract Surg 200632849-585.
• Gatinel D. Limited accuracy of Hartmann-Shack
  wavefront sensing in eyes with diffractive
  multifocal IOLs letter. J Cataract Refract
  Surg 200834528
• Jendritza BB, Knorz MC, Morton S.
  Wavefront-guided excimer laser vision correction
  after multifocal IOL implantation. J Refract
  Surg 200824274-279.

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References

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• Altmann GE, Nichamin LD, Lane SS, Pepose JS.
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