title: The combined (Genesis) technique of radial keratotomy. A prospective, multicenter study. Refractive Keratoplasty Study Group.
abstract: OBJECTIVE
  A prospective, multicenter, clinical study to evaluate a standardized surgical (Genesis) protocol which includes combined-technique radial incisions in patients seeking reduction of their physiologic myopia. The combined incisions were designed to incorporate the safety of the centrifugal incision technique with the efficacy of the centripetal incision technique.
  
  
  METHODS
  A total of 375 eyes undergoing radial keratotomy procedures performed in six different clinical centers were analyzed. All procedures were performed in accordance with the Genesis nomograms. The Genesis protocol called for using preoperative screening pachymetry to guide central clear zone size selection, incising the thinnest corneal quadrant first, suturing corneal perforations, and discouraged more than one enhancement procedure, when indicated. Globe fixation technique served as a study variable.
  
  
  RESULTS
  Mean follow-up was 6.2 months (range, 1.5-12 months). Mean residual cycloplegic refraction was -0.48 +/- 0.61 diopters (D) (range, -2.50 to +1.50 D); 92% of eyes were within 1 D of the planned goal of -0.50 D and 85% were within 1 D of emmetropia; 14% were myopic; and 1% was hyperopic by more than 1 D. Uncorrected visual acuity was 20/40 or better in 95% of eyes; the remaining 5% retaining myopic refractive errors. A single procedure was performed in 73% of eyes, and 99% received less than two enhancements. Of eyes with no enhancements, 97% had uncorrected visual acuity of 20/40 or better. One study eye (0.3%) had a two-line loss of spectacle visual acuity. There were no invasions of the central clear zone. Globe fixation was a significant predictor for enhancement incidence (P < 0.001) but not for perforation incidence (P = 0.06). Incision sequence was predictive for perforation incidence (P < 0.0002).
  
  
  CONCLUSIONS
  The combined-technique of radial keratotomy, coupled with the Genesis surgical protocol, affords centrifugal incision safety with centripetal incision efficacy. The Genesis nomograms, with a built in refractive outcome goal of -0.50 D provide an acceptable degree of accuracy and predictability while guarding against hyperopic overcorrection.
authors.affiliation: Anheuser-Busch Eye Institute,0 Saint Louis University, Health Sciences Center, USA.
authors.forename: S M
authors.initials: SM
authors.lastname: Verity
authors.forename: J H
authors.initials: JH
authors.lastname: Talamo
authors.forename: A
authors.initials: A
authors.lastname: Chayet
authors.forename: T C
authors.initials: TC
authors.lastname: Wolf
authors.forename: P
authors.initials: P
authors.lastname: Rapoza
authors.forename: D J
authors.initials: DJ
authors.lastname: Schanzlin
authors.forename: S
authors.initials: S
authors.lastname: Lane
authors.forename: K
authors.initials: K
authors.lastname: Kenyon
authors.forename: K K
authors.initials: KK
authors.lastname: Assil
mesh_terms: D000328:Adult; D003315:Cornea / Q000503:physiopathology / Q000601:surgery*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007646:Keratotomy, Radial / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009216:Myopia / Q000503:physiopathology / Q000601:surgery*; D011182:Postoperative Care; D011446:Prospective Studies; D012029:Refraction, Ocular / Q000502:physiology; D016896:Treatment Outcome; D014792:Visual Acuity / Q000502:physiology