title: Beveled femtosecond laser astigmatic keratotomy for the treatment of high astigmatism post-penetrating keratoplasty.
abstract: OBJECTIVE
  To use beveled femtosecond laser astigmatic keratotomy (FLAK) incisions to treat high astigmatism after penetrating keratoplasty.
  
  
  METHODS
  Paired FLAK incisions at a bevel angle of 135 degrees, 65% to 75% depth, and arc lengths of 60 to 90 degrees were performed using a femtosecond laser. One case of perpendicular FLAK was presented for comparison. Vector analysis was used to calculate the changes in astigmatism. Fourier domain optical coherence tomography was used to examine incision morphology.
  
  
  RESULTS
  Wound gaping requiring suturing was observed in the case of perpendicular FLAK. Six consecutive cases of beveled FLAK were analyzed. Fourier domain optical coherence tomography showed that beveled FLAK caused a mean forward shift of Bowman layer anterior to the incisions of 126 ± 38 μm, with no wound gaping. The mean magnitude of preoperative keratometric astigmatism was 9.8 ± 2.9 diopters (D), and postoperatively it was 4.5 ± 3.2 D (P < 0.05). Uncorrected visual acuity improved from 1.24 ± 0.13 logarithm of the minimum angle of resolution preoperatively to 0.76 ± 0.38 postoperatively (P < 0.05). Best spectacle-corrected visual acuity improved from 0.43 ± 0.33 logarithm of the minimum angle of resolution preoperatively to 0.27 ± 0.24 postoperatively (P = 0.22). Visual results were reduced in 2 patients by cataract progression. Between 1 and 3 months after beveled FLAK, the keratometric cylinder was stable (<1 D change) in 5 of 6 patients, and regressed in 1 patient. No complications occurred.
  
  
  CONCLUSIONS
  Beveled FLAK incisions at varied depth are effective in the management of postkeratoplasty astigmatism. Early postoperative changes stabilized within 1 month in most patients. Further studies are needed to assess long-term outcomes.
authors.affiliation: Oregon Health and Science University, Portland, OR, USA.
authors.forename: Catherine
authors.initials: C
authors.lastname: Cleary
authors.forename: Maolong
authors.initials: M
authors.lastname: Tang
authors.forename: Habeeb
authors.initials: H
authors.lastname: Ahmed
authors.forename: Martin
authors.initials: M
authors.lastname: Fox
authors.forename: David
authors.initials: D
authors.lastname: Huang
mesh_terms: D001251:Astigmatism / Q000209:etiology / Q000503:physiopathology / Q000601:surgery*; D003315:Cornea / Q000503:physiopathology / Q000601:surgery*; D003316:Corneal Diseases / Q000601:surgery; D063171:Corneal Pachymetry; D019781:Corneal Topography; D005260:Female; D005583:Fourier Analysis; D006801:Humans; D015948:Keratoplasty, Penetrating; D054018:Lasers, Excimer / Q000627:therapeutic use*; D008297:Male; D010865:Pilot Projects; D011183:Postoperative Complications; D011446:Prospective Studies; D041623:Tomography, Optical Coherence; D014792:Visual Acuity / Q000502:physiology