Long-term Surgically Induced Astigmatism After Toric Iris-fixated Lens Implantation in Post-keratoplasty and Virgin Eyes

1
Long-term Surgically Induced Astigmatism After
Toric Iris-fixated Lens Implantation in
Post-keratoplasty and Virgin Eyes
World Cornea Congress VI April 7-9 Boston
Nienke Visser, Tos T.J.M. Berendschot, Rudy
M.M.A. Nuijts University Eye Clinic, Academic
Hospital Maastricht, the Netherlands

• The authors have no financial interest in the
  subject matter of this poster.

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Purpose

• To compare the long-term changes in corneal
  astigmatism induced by
• toric iris-fixated intraocular lens (IOL)
  implantation in
• post-keratoplasty patients and patients with no
  previous ocular surgery.

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Methods

• Retrospective study
• Exclusion criteria corneal pathologies
• laser refractive surgery
• other corneal surgery after Artisan
  implantation
• Groups 1. no previous ocular surgery (control
  group)
• 2. post-keratoplasty (PK group)
• Toric iris-fixated IOL (Artisan,Ophtec BV, the
  Netherlands)
• 5.4 mm superior incision

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Methods Surgically induced astigmatism (SIA)

• Determined by corneal topographies (Eyemap,
  Alcon, TX, USA) - preop
• - 6 months postop
• - 3 years postop
• Individual cylinder axis ? Cartesian coordinate
  (x,y)
• SIA calculated by standard vector analysis 1
• SIA displayed in double angle minus cylinder
  plots

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Example
Diopters
2
1
0
90
Diopters
1
1
2
2
1
2
135
1. Holladay JT et al. Analysis of aggregate
surgically induced refractive change, prediction
error, and intraocular astigmatism. J Cataract
Refract Surg 2001 2761-79.
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Methods Covariates influencing the SIA

• Multivariate linear modelling
• Following possible covariates were examined

Control group PK group
Age Age
Preoperative astigmatism Preoperative astigmatism
Incision location (on steep/ flat axis) Incision location (on steep/ flat axis)
Time between PK and IOL implantation
Indication for PK
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Results Preoperative astigmatism
Control group PK group P value
Number of eyes 38 35
Age (years) 46 8 64 15 lt0.001
Preoperative corneal astigmatism -1.40 1.04 D _at_ 1 12 -1.19 5.50 D _at_ 168 16 0.762
PK group
Control group
Double angle minus cylinder plot, with an ellipse
of 1 standard deviation (SD)
Double angle minus cylinder plot, with an ellipse
of 1 SD
? No significant differences in mean preoperative
astigmatism between two groups
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Results SIA
PK group
Control group
Double angle minus cylinder plot, with an ellipse
of 1SD
Double angle minus cylinder plot, with an ellipse
of 1 SD
Control group PK group P value
SIA at 6 months -0.47 0.53 D _at_ 88 12 -0.59 2.02 D _at_ 71 14 0.606
SIA at 3 years -0.76 0.59 D _at_ 89 12 -1.29 2.73 D _at_ 98 15 0.478
? No significant differences in SIA between the
two groups ? Variability in SIA much larger in PK
group
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Results Covariates influencing the SIA
Control group The amount of preoperative
astigmatism was a covariate significantly
influencing the SIA at 3 years postoperatively
(plt0.001).
Control group
PK group
This continues variable was categorized in order
to demonstrate its influence. Data shown as mean
SIA with an ellipse of one SD.
PK group Fuchs endothelial dystrophy as the
indication for PK was a covariate significantly
influencing the SIA at 3 years postoperatively
(p0.026).
Data shown as mean SIA with an ellipse of one SD.
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Conclusion

• Toric iris-fixated lens implantation induced a
  more variable amount of SIA in PK eyes, compared
  to control eyes.
• We recommend to incorporate the expected SIA into
  the lens power calculation in control and PK
  eyes.

Contact nienke.visser_at_mumc.nl