Mariko Shirayama, M'D, Li Wang, M'D' Ph'D,

1
Prediction of IOL position using Galilei

• Mariko Shirayama, M.D, Li Wang, M.D. Ph.D,
• Mitchell P Weikert, M.D, Douglas D Koch, M.D.
• Cullen Eye Institute, Baylor College of Medicine,
• Houston, TX.
• Financial Interest Disclosure none

2
Purpose

• Inaccurate estimation of postoperative effective
  lens position is the leading cause of error in
  the accuracy of IOL calculations
• To investigate if the postoperative intraocular
  lens (IOL) position could be predicted
  preoperatively using data obtained from the
  Galilei Dual Scheimpflug Analyzer
• Norrby S. Sources of error in intraocular
  lens power calculation.
• J Cataract Refractive Surg 2008 34 368-376

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Methods

• Prospectively, a case series of 28 eyes of 27
  patients who underwent cataract extraction by
  phacoemulsification with implantation of the
  SN60WF, SA60AT or SN60T5 by a single surgeon were
  enrolled.
• Preoperatively, corneal refractive power (SimK),
  corneal diameter, anterior chamber diameter,
  chamber angles, and anterior chamber depth (ACD)
  were measured using the Galilei.
• Three weeks following cataract surgery, the IOL
  position was measured using Galilei. Using a
  digital caliper, the distance from the
  endothelium to the IOL surface was measured in up
  to ___ meridians (depending on the quality of the
  images).

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Data Analysis

• Because of the small sample size to date, simple
  regression analysis was used to determine if the
  postoperative IOL position could be predicted
  based on the preoperative measurements from the
  Galilei.
• With a larger sample size, multiple regression
  will be used.

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Result Preoperative ACD vs. Postoperative ACD
mm

4.00
3.50
3.00
3.41
2.50
2.00
2.55
1.50
1.00
0.50
0.00
Postoperative ACD
Preoperative ACD

• The difference between preoperative ACD and
• postoperative ACD was significant. (
  Plt0.0001)

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Result Pre-ACD versus Post-ACD
3.9
3.7
3.5
3.3
Postoperative ACD
3.1
y 0.1992x 2.904
2.9
R2 0.2153
2.7
2.5
1
1.5
2
2.5
3
3.5
4
Preoperative ACD

• Postoperative ACD was positively correlated with
  preoperative ACD (P0.012).

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Result Pre-ACD versus difference between
post-ACD and pre-ACD
2
y -0.8008x 2.9041
1.5
R2 0.8161
1
Differences (mm) (Post-op ACD - Preop ACD)
0.5
0
1
1.5
2.0
2.5
3.0
3.5
4.0
-0.5
Pre-op ACD (mm)

• The differences between postoperative ACD and
  preoperative ACD were highly negatively
  correlated with preoperative ACD (Plt0.001).

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Result Corneal values versus Post-op ACD
4
3.8
3.6
3.4
3.2
Post-ACD (mm)
3
2.8
2.6
y -0.0405x 5.1781
2.4
R2 0.0803
2.2
2
39.00
40.00
41.00
42.00
43.00
44.00
45.00
46.00
47.00
Galilei SimK (D)

• Postoperative ACD tended to decrease with
  increasing GALILEI simulated K values (P0.145).

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Limitations

• Small number of the subjects enrolled
• Study is ongoing to include more subjects
• Other factors, such as the corneal diameter and
  AC diameter, could not be evaluated
• Postoperative ACD was measured from corneal
  endothelium to the surface of the IOL
• Thickness and diopter of the IOL were not
  considered

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Discussion

• In our study, postoperative ACD tended to be
  negatively correlated with the corneal power with
  Galilei.
• Differs from most IOL formulas a deeper
  postoperative ACD is predicted in eyes with
  steeper corneas
• Corneal diameter may play an important role
  heresteeper corneas could be associated with
  smaller corneal diameters
• Multiple regression in larger number of eyes is
  desirable

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Discussion

• Differences between postoperative ACD and
  preoperative ACD decreased significantly with
  increasing preoperative ACD
• the postoperative ACD might be predicted with
  preoperative ACD using the Galilei
• Differences between postoperative ACD and
  preoperative ACD decreased significantly with
  increasing AL (p0.013)

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Conclusion

• We evaluated the role of the new device Galilei
  to predict the postoperative ACD. The
  preoperative ACD might predict the postoperative
  ACD.
• Study is ongoing to include more subjects with
  cataract extraction and IOL implantation.

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Conclusion

• Ultimate goal is to analyze the interaction of
  several preoperative measures to determine if one
  can more reliably predict postoperative effective
  lens position
• These would include
• Corneal power
• Corneal diameter
• AC diameter
• AC angle
• AC depth
• Axial length