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Effect of Preoperative Pupil Size on Quality of Vision After Wavefront-Guided LASIK

This study has been completed.
Information provided by:
Stanford University Identifier:
First received: February 12, 2009
Last updated: April 28, 2009
Last verified: April 2009
The purpose of this study is to evaluate whether the size of the pupil has an effect on quality of vision in patients undergoing LASIK surgery.

Condition Intervention Phase
Procedure: LASIK
Phase 4

Study Type: Interventional
Study Design: Allocation: Non-Randomized
Intervention Model: Single Group Assignment
Masking: Open Label
Primary Purpose: Treatment
Official Title: Effect of Preoperative Pupil Size on Quality of Vision After Wavefront-Guided LASIK

Further study details as provided by Stanford University:

Enrollment: 51
Study Start Date: May 2004
Study Completion Date: November 2005
Primary Completion Date: November 2005 (Final data collection date for primary outcome measure)
Arms Assigned Interventions
Active Comparator: small Procedure: LASIK
laser-assisted in situ keratomileusis
Other Name: laser-assisted in situ keratomileusis
Active Comparator: medium Procedure: LASIK
laser-assisted in situ keratomileusis
Other Name: laser-assisted in situ keratomileusis
Active Comparator: large Procedure: LASIK
laser-assisted in situ keratomileusis
Other Name: laser-assisted in situ keratomileusis

Detailed Description:

Purpose: To prospectively evaluate the effect of preoperative pupil size on quality of vision after wavefront-guided LASIK.

Methods: Fifty-one patients underwent LASIK for low myopia and completed questionnaires regarding specific visual symptoms before and after surgery. Each eye was evaluated postoperatively at 1-week, 1-, 3-, 6- and 12-months. Pupils were stratified according to size: small (<5.5mm), medium (5.5 to 6.0mm) and large (>6.0mm). Mesopic pupil size and preoperative and postoperative variables were evaluated using analysis of variance (ANOVA). A regression model was also performed to determine the correlation between mean spherical equivalent and cylinder and visual symptoms.


Ages Eligible for Study:   Child, Adult, Senior
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No

Inclusion Criteria:

  1. no more than 6.00 D of spherical myopia
  2. no more than 3.00 D of refractive astigmatism
  3. a stable refraction (less than 0.50D per year of sphere or cylinder)
  4. a corneal diameter of less than 11.0 mm to allow for suction ring fixation
  5. discontinuation of soft contact wear at least 7 days prior to preoperative evaluation
  6. visual acuity correctable to at least 20/20
  7. age older than 21 years
  8. ability to participate in follow-up examinations for 12 months after LASIK surgery

Exclusion Criteria:

  1. use of rigid gas permeable contact lens
  2. severe dry eye symptoms
  3. severe blepharitis
  4. anterior segment abnormalities (i.e. cataracts, corneal scarring, or neovascularization within 1 mm of intended ablation zone)
  5. recurrent corneal erosion
  6. severe basement membrane disease
  7. progressive or unstable myopia or keratoconus
  8. unstable corneal mires on central keratometry
  9. corneal thickness in which LASIK procedure would result in less than 250 microns of remaining posterior corneal thickness below the flap postoperatively
  10. baseline standard manifest refraction of more than 0.75 D in sphere power
  11. or a difference of greater than 0.50 D in cylinder power compared with baseline standard cycloplegic refraction
  12. a baseline standard cycloplegic refraction differing more than 0.75 in sphere, 0.50 D in cylinder
  13. have a different type of astigmatism (i.e. with-the-rule) when the cylinder is greater than 0.50D compared to baseline standard cycloplegic refraction
  14. preoperative assessment of ocular topography and/or aberrations indicates that either eye is not suitable candidate for LASIK vision correction procedure (i.e. forme fruste keratoconus
  15. corneal warpage, or pellucid marginal degeneration)
  16. previous intraocular or corneal surgery
  17. history of herpes zoster or simplex keratitis
  18. patients on systemic corticosteroid or immunosuppressive therapy
  19. immunocompromised subjects or clinically significant atopic disease
  20. connective tissue disease
  21. diabetes
  22. steroid responder
  23. macular pathology
  24. pregnant or lactating patients
  25. patients with sensitivity to planned study concomitant medications
  26. patients participating in another ophthalmic drug or device clinical trial
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Please refer to this study by its identifier: NCT00889941

United States, California
Stanford University School of Medicine
Stanford, California, United States, 94305
Sponsors and Collaborators
Stanford University
Sub-Investigator: Annie Chan Stanford University
Principal Investigator: Edward E. Manche Stanford University
  More Information

Responsible Party: Edward Manche, MD, Stanford University Identifier: NCT00889941     History of Changes
Other Study ID Numbers: SU-02082009-1758
Study First Received: February 12, 2009
Last Updated: April 28, 2009 processed this record on April 28, 2017