title: Aberrations induced in wavefront-guided laser refractive surgery due to shifts between natural and dilated pupil center locations.
abstract: OBJECTIVE
  To determine the aberrations induced in wavefront-guided laser refractive surgery due to shifts in pupil center location from when aberrations are measured preoperatively (over a dilated pupil) to when they are corrected surgically (over a natural pupil).
  
  
  METHODS
  Center for Visual Science and Department of Ophthalmology, University of Rochester, Rochester, New York, USA.
  
  
  METHODS
  Shifts in pupil center were measured between dilated phenylephrine hydrochloride (Neo-Synephrine [2.5%]) and nonpharmacological mesopic conditions in 65 myopic eyes treated with wavefront-guided laser in situ keratomileusis (Technolas 217z, Bausch & Lomb). Each patient's preoperative and 6-month postoperative wave aberrations were measured over the dilated pupil. Aberrations theoretically induced by decentration of a wavefront-guided ablation were calculated and compared with those measured 6 months postoperatively (6.0 mm pupil).
  
  
  RESULTS
  The mean magnitude of pupil center shift was 0.29 mm +/- 0.141 (SD) and usually occurred in the inferonasal direction as the pupil dilated. Depending on the magnitude of shift, the fraction of the higher-order postoperative root-mean-square wavefront error that could be due theoretically to pupil center decentrations was highly variable (mean 0.26 +/- 0.20 mm). There was little correlation between the calculated and 6-month postoperative wavefronts, most likely because pupil center decentrations are only 1 of several potential sources of postoperative aberrations.
  
  
  CONCLUSIONS
  Measuring aberrations over a Neo-Synephrine-dilated pupil and treating them over an undilated pupil typically resulted in a shift of the wavefront-guided ablation in the superotemporal direction and an induction of higher-order aberrations. Methods referencing the aberration measurement and treatment with respect to a fixed feature on the eye will reduce the potential for inducing aberrations due to shifts in pupil center.
authors.affiliation: Center for Visual Science, University of Rochester, Rochester, New York 14627, USA. jporter@cvs.rochester.edu
authors.forename: Jason
authors.initials: J
authors.lastname: Porter
authors.forename: Geunyoung
authors.initials: G
authors.lastname: Yoon
authors.forename: Diana
authors.initials: D
authors.lastname: Lozano
authors.forename: Jessica
authors.initials: J
authors.lastname: Wolfing
authors.forename: Remy
authors.initials: R
authors.lastname: Tumbar
authors.forename: Scott
authors.initials: S
authors.lastname: Macrae
authors.forename: Ian G
authors.initials: IG
authors.lastname: Cox
authors.forename: David R
authors.initials: DR
authors.lastname: Williams
mesh_terms: D000328:Adult; D003315:Cornea / Q000503:physiopathology / Q000601:surgery*; D006801:Humans; D020731:Keratomileusis, Laser In Situ / Q000009:adverse effects* / Q000379:methods; D009184:Mydriatics / Q000008:administration & dosage*; D009216:Myopia / Q000601:surgery*; D010656:Phenylephrine / Q000008:administration & dosage; D011183:Postoperative Complications; D011680:Pupil / Q000187:drug effects* / Q000502:physiology; D012030:Refractive Errors / Q000209:etiology*
chemical_list: D009184:Mydriatics; D010656:Phenylephrine