title: Correction of astigmatism using positive and negative cylinder programs with the Nidek EC-5000 excimer laser.
abstract: BACKGROUND
  The efficacy of a current program of positive cylinder treatment was evaluated and compared to a previous program of negative cylinder treatment.
  
  
  METHODS
  The authors performed a comparative analysis of 123 eyes (72 patients) who underwent LASIK using the Nidek EC-5000 excimer laser with the formula developed by Chayet and the positive cylinder (71 eyes of 52 patients) and negative cylinder programs (52 eyes of 31 patients).
  
  
  RESULTS
  A faster stabilization of correction and a marked reduction of stromal tissue ablated were obtained with the positive cylinder program than with the negative cylinder program. This was directly related to the amount of preoperative ametropia.
  
  
  CONCLUSIONS
  The spectrum of ametropias that can be treated with LASIK is increased with the positive cylinder program because less tissue is ablated.
authors: Instituto del Ojo Molina, Gabriel Rene Moreno University, Santa Cruz, Bolivia.
authors: R
authors: R
authors: Molina
authors: R
authors: R
authors: Monasterio
authors: E
authors: E
authors: Soliz
authors: J
authors: J
authors: Foianini
mesh_terms: D001251:Astigmatism / Q000601:surgery*; D003315:Cornea / Q000601:surgery*; D016039:Corneal Transplantation / Q000379:methods*; D005500:Follow-Up Studies; D006801:Humans; D053685:Laser Therapy / Q000379:methods*; D055095:Optics and Photonics; D012029:Refraction, Ocular; D016896:Treatment Outcome