Does phacoemulsification alter pupil size and position

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Does phacoemulsification alter pupil size and
position

• Sanghamitra Burman MD FRCS
• Julian D. Stevens MD FRCOphth
• Moorfields Eye Hospital, London, UK
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Aim

• Purpose To determine the changes in pupil size
  and position following uncomplicated clear
  corneal phacoemulsification
• Setting Anterior Segment and Refractive Surgery
  Service, Moorfields Eye hospital, London, UK
• Study Design A prospective, non-comparative,
  interventional case series

Hartman-Shack Aberrometer
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Methods

• 23 healthy subjects including 9 men and 14 women
  scheduled to have cataract surgery or refractive
  lens surgery were recruited in this study.
• Clear corneal phacoemulsification was performed
  for cataract in 20 patients and for refractive
  lens exchange in 3 patients.
• The scotopic pupil size in 34 eyes was measured
  with a Hartman-Shack wavefront aberrometer (Visx
  WaveScan).
• Measurements were performed preoperatively and
  between 4-10 weeks postoperatively.
• A single surgeon operated upon all the eyes and a
  single observer performed all measurements.

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Results
Distribution of change in pupil size and centre
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Results

• Paired Students t-test was used to evaluate the
  differences.
• p value 0.159
• There was no statistically significant
  difference between preoperative
• and postoperative mean scotopic pupil sizes.
• The shift in pupil center does not show a trend.
  
• For most eyes the postoperative pupil was
  smaller.

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Discussion

• The integration of wavefront technology and lens
  based surgery represents a step toward improving
  functional vision and quality of life for
  cataract patients. The Tecnis Z9000 IOL (Pfizer,
  New York) has been designed with a modified
  prolate anterior surface to compensate for the
  spherical aberrations of the cornea, thus
  eliminating total spherical aberration.1Results
  show that the Tecnis IOL may produce better
  contrast sensitivity than a standard spherical
  IOL under mesopic and photopic conditions.2 If
  this modified prolate IOL was centered within 0.5
  mm and tilted less than 7 degrees, it would
  exceed the optical performance of a conventional
  spherical IOL. 3
• Pupillary alterations may have implications on
  the implantation of prolate intraocular lenses
  (IOL) and refractive surgery for post cataract
  surgery residual refractive errors. A shift in
  pupil position may negate the benefits of
  aspheric IOL implantation.

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Conclusions

• In the present study uncomplicated clear corneal
• phacoemulsification did not significantly modify
• scotopic pupil size or position.
• References
• Packer M, Fine IH, Hoffman RS. Wavefront
  technology in cataract surgery. Curr Opin
  Ophthalmol. 200415(1)56-60.
• Packer M, Fine IH, Hoffman RS, Piers PA. Improved
  functional vision with a modified prolate
  intraocular lens. J Cataract Refract Surg.
  200430(11)2247-8.
• Holladay JT, Piers PA, Koranyi G, van der Mooren
  M, Norrby NE. A new intraocular lens design to
  reduce spherical aberration of pseudophakic eyes.
  J Refract Surg. 2002 18(6) 683-91.
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