title: Effects of lamellar keratotomy on postkeratoplasty astigmatism.
abstract: OBJECTIVE
  To determine the changes in postkeratoplasty astigmatism induced by lamellar keratotomy.
  
  
  METHODS
  A prospective, non-randomised comparative trial of patients undergoing a hinged lamellar corneal flap for treatment of significant astigmatism after penetrating keratoplasty. Uncorrected visual acuity, best corrected visual acuity, refraction, and corneal topography were assessed at 1 and 3 months after the lamellar keratotomy.
  
  
  RESULTS
  17 eyes in 16 patients (13 M, 3F) were included in the study (mean age 48.2 years; range 20-86 years). Six of 17 eyes (35.3%) changed more than 1 dioptre (D) in spherical equivalent by 3 months. Nine of 17 eyes (52.9%) changed more than 1 D in sphere by 3 months. 12 of 17 eyes (70.6%) changed more than 1 D in refractive cylinder. Seven patients of 15 (46.7%) changed more than 1 D in corneal power as measured topographically. Five of 17 eyes (29.4%) changed in refractive cylinder axis more than 15 degrees and this was similar to the change measured topographically of four of 15 eyes (26.7%). Vector analysis showed 60% of eyes had a surgically induced astigmatism (SIA) vector of more than 1 D, including a net corneal astigmatism decrease of more than 1 D in four eyes and increase of more than 1 D in two eyes at 3 months after surgery. Complications of the lamellar keratotomy included two partial buttonholes and one partial wound dehiscence.
  
  
  CONCLUSIONS
  The creation of a lamellar flap alone can have significant effects on the astigmatism following penetrating keratoplasty. LASIK for correction of postkeratoplasty astigmatism may be more accurately performed as a two stage procedure rather than a single stage, after the corneal effects of the lamellar keratotomy have stabilised.
authors.affiliation: Cornea and External Disease Service, Moorfields Eye Hospital, London, UK. mdglee@hotmail.com
authors.forename: G A
authors.initials: GA
authors.lastname: Lee
authors.forename: J J
authors.initials: JJ
authors.lastname: Pérez-Santonja
authors.forename: A
authors.initials: A
authors.lastname: Maloof
authors.forename: L A
authors.initials: LA
authors.lastname: Ficker
authors.forename: J K G
authors.initials: JK
authors.lastname: Dart
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001251:Astigmatism / Q000209:etiology / Q000601:surgery*; D005260:Female; D006801:Humans; D020731:Keratomileusis, Laser In Situ / Q000009:adverse effects / Q000379:methods*; D015948:Keratoplasty, Penetrating / Q000009:adverse effects*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012030:Refractive Errors / Q000503:physiopathology; D013524:Surgical Flaps; D016896:Treatment Outcome; D014792:Visual Acuity / Q000502:physiology