title: IntraLase-enabled astigmatic keratotomy for post-keratoplasty astigmatism: on-axis vector analysis.
abstract: OBJECTIVE
  To determine the refractive predictability, stability, efficacy, and complication rate of femtosecond laser-enabled astigmatic keratotomy for post-keratoplasty astigmatism.
  
  
  METHODS
  A retrospective case series (pilot study).
  
  
  METHODS
  Thirty-seven eyes of 34 patients.
  
  
  METHODS
  All eyes underwent IntraLase-enabled astigmatic keratotomy for high astigmatism (>5 diopters [D]) after penetrating keratoplasty.
  
  
  METHODS
  Uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA), manifest refraction, higher-order aberrations, and complications.
  
  
  RESULTS
  Mean follow-up was for 7.2 months. Uncorrected visual acuity improved from a mean of 1.08+/-0.34 logarithm of the minimum angle of resolution preoperatively to a mean of 0.80+/-0.42 postoperatively (P=0.0016). Best-corrected visual acuity improved from a mean of 0.45+/-0.27 preoperatively to 0.37+/-0.27 postoperatively (P=0.018). The defocus equivalent was significantly reduced by more than 1 D (P=0.025). The value of absolute astigmatism was reduced from 7.46+/-2.70 D preoperatively to 4.77+/-3.29 D postoperatively (P=0.0001). Higher-order aberrations were significantly increased. The efficacy index was 0.6+/-0.6. There were no cases of perforation, wound dehiscence, or infectious keratitis. Three eyes (8%) experienced an episode of graft rejection. Overcorrection occurred in 9 eyes (24%).
  
  
  CONCLUSIONS
  IntraLase-enabled astigmatic keratotomy is an effective treatment for high astigmatism after penetrating keratoplasty with an encouraging refractive predictability. Future studies may help refine the treatment parameters required to achieve reduction of cylinder with greater accuracy.
authors.affiliation: Department of Ophthalmology and Vision Sciences, Toronto Western Hospital, University of Toronto, Ontario, Canada. nik_kumar1@yahoo.com
authors.forename: Nikhil L
authors.initials: NL
authors.lastname: Kumar
authors.forename: Igor
authors.initials: I
authors.lastname: Kaiserman
authors.forename: Raneen
authors.initials: R
authors.lastname: Shehadeh-Mashor
authors.forename: Wiwan
authors.initials: W
authors.lastname: Sansanayudh
authors.forename: Rusty
authors.initials: R
authors.lastname: Ritenour
authors.forename: David S
authors.initials: DS
authors.lastname: Rootman
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001251:Astigmatism / Q000209:etiology / Q000503:physiopathology / Q000601:surgery*; D003315:Cornea / Q000503:physiopathology / Q000601:surgery*; D019781:Corneal Topography; D005260:Female; D006801:Humans; D015948:Keratoplasty, Penetrating; D054018:Lasers, Excimer / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications; D012029:Refraction, Ocular / Q000502:physiology; D012189:Retrospective Studies; D014792:Visual Acuity / Q000502:physiology; D055815:Young Adult