Influence of the Compensation for Pupil Decentration and Ocular Rotation on the Residual Ocular Aber

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Influence of the Compensation for Pupil
Decentration and Ocular Rotation on the Residual
Ocular Aberrations in Myopic Astigmatic Patients
After Wavefront Guided Refractive Surgery

• Marotte D, Denoyer A, Pisella PJ.
• University François Rabelais
• Hospital Bretonneau, Tours, France
• No Financial interest

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Does the iris recognition reduce the
postoperative cylindrical error and treatment
induced high order aberrations in the astigmatic
patients undergoing W-G refractive surgery ?
Courtesy of D.Marotte
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Alpins method
This method described by Dr Noel Alpins is a
vector analysis tool which provides the ability
to calculate and statistically compare the
magnitudes and axes of astigmatic change
(vectors) separately. This method can allow
the analyses of mean and standard deviations of
calculated index for the evaluation of errors,
surgical success and secondary adjustments
required for final results improvement..
Courtesy of D.Marotte
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Study design
Prospective comparative study (University
Hospital of Tours, France)

• 71 myopic eyes with astigmatism gt 1 D underwent
  WG photoablation ( Excimer Star S4-IR and
  CustomVue, Visx, USA)
• 32 with iris-guided compensation (IGC)
• 39 controls without IGC

• 6-month postoperative outcomes
• Main Accuracy of cylindrical treatment using
  Alpins method taking into account magnitude and
  axis of error.
• Others UCVA, BCVA, induced ocular wavefront
  aberrations

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Preoperative features
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Cylindrical error (6 months)

Statistical difference in the
achieved/intented vector magnitude ratio
84.3614,64 vs 5129.6 , plt0.000001
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Accuracy of Cylindrical Treatment using Alpins
method


plt0.05
plt0.05



High statistical difference in the Magnitude and
Axe of Error in the All group (plt0.0001)
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Induced high order aberrations (6 months)


HOA induction is lower in the PRK-IGC group
Satistical difference in the Total Hoa and
Trefoil induced for PRK group (plt0.05)
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Conclusions

• The accuracy of cylindrical treatment by
  compensating peroperative ocular torsions, is
  independent from the surgical procedure.
• The treatment induced HOA(s) are more limited
  with the benefit of iris guided compensation
  after PRK .
• Because of the flap and change of biophysical
  properties of the cornea (healing phenomena), the
  Lasik procedures induce more aberrations.
• Compensating ocular misalignments during WG
  refractive surgery reduces the residual
  astigmatism,and optimises the treatment of
  higher-order aberrations in myopic astigmatic
  patients.