Comparison in Reduction of Preoperative Astigmatism after Cataract Surgery with Toric IOLs versus Limbal Relaxing Incisions Alexander Chop PhD MD (no financial interests to disclose) Dan Straka

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Comparison in Reduction of Preoperative
Astigmatism after Cataract Surgery with Toric
IOLs versus Limbal Relaxing IncisionsAlexander
Chop PhD MD(no financial interests to
disclose)Dan Straka Asmaneh Siavosh M4(no
financial interests to disclose)William G.
Martin MD, FACS(consultant to Alcon and
AMO)The University of Toledo College of
Medicine
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Introduction

• There are three main options for reducing
  astigmatism at or around the time of cataract
  surgery, namely performing one or more limbal
  relaxing incisions (LRIs), implanting an
  intraocular lens known as a Toric IOL which
  corrects for astigmatism and finally
  postoperative PRK. Here we compare the short term
  results of the first two methods at the three
  month postoperative period.

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Disadvantages of LRIs

• Technique is less precise than a Toric IOL - the
  cornea may undergo an over-correction or
  under-correction.
• The cornea will heal over time, altering the
  result.
• The depth, length and curvature of the wound will
  vary both within each eye and between eyes and
  patients, as well as surgeons.

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Disadvantages of Toric IOls

• Cost - generally more expensive than LRIs.
• Concern over rotational stability of the lens in
  the bag.
• Amount of correction available is not as great as
  with LRIs and has larger steps between lens
  powers compared to LRIs.

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Retrospective Study Design

• Chart review from 2006 -2008 comparing 32 eyes of
  patients undergoing LRI at the time of cataract
  surgery using the Alcon SN60WF IOL with 37 eyes
  of patients undergoing implantation with the
  Alcon AcrySof SN60T3/4/5 Toric IOL, matched for
  cataract density, age and sex and treated using
  the Wallace LRI nomogram and IOL Master.
• Consistency all procedures performed by the same
  surgeon (WGM) in the same ASC using the same
  superior scleral tunnel approach with pre- and
  postoperative measurements by the same technicians

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Results for LRIs Alcon SN60WF IOL Implantation

• Residual postoperative astigmatism measured at 3
  months (N 32) reflects an improvement of 1.41 D
  cylinder (64 reduction in astigmatism)
• LRI patient average preoperative cylinder 2.20
  D (range 0.75 - 6.00)
• LRI patient average postoperative cylinder 0.79
  D (range plano - 3.00)

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Results for Alcon SN60T3/4/5 Toric IOL
Implantation

• Residual postoperative astigmatism measured at 3
  months (N 37) reflects an improvement of 2.25 D
  cylinder (77 reduction in astigmatism)
• Toric IOL average preoperative cylinder 2.92 D
  (range 1.50 - 4.75)
• Toric IOL average postoperative cylinder 0.67
  D (range plano - 2.50)
  
  
  
  

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Conclusion

• Both methods are effective in reducing
  preoperative astigmatism and both should be
  offered to patients.
• At the three month postoperative period, the
  Toric IOL shows a slightly greater reduction in
  preoperative astigmatism (77 compared to 64)
  but was not statistically significant. Average
  Toric IOL patient had more preoperative
  astigmatism than LRI patient, potentially biasing
  results.
• Longer term results of at least the three year
  postoperative period must be measured.
• Prospective study is needed with patients matched
  for equal preoperative astigmatism and
  controlling all other variables.