title: Effect of incision direction on refractive outcome after radial keratotomy.
abstract: OBJECTIVE
  Radial keratotomy incisions can be made centripetally or centrifugally. The benefits and effects of both techniques have been disputed since American surgeons began performing RK in the late 1970s. We examined the RK databases of a single surgeon to determine if incision direction was associated with refractive outcome.
  
  
  METHODS
  Stepwise regression was employed to select the important predictors of refraction change in the population. In addition to incision direction, variables eligible for entry into the model were optic clear zone diameter, incision number, patient age, corneal curvature and planned incision depth.
  
  
  RESULTS
  All variables except for planned incision depth and corneal power entered the model.
  
  
  CONCLUSIONS
  The results were consistent with previous investigations that found incision number, optic clear zone diameter and patient age important predictors of outcome. We also found incision direction to be a significant predictive variable with centripetal incisions decreasing myopia 0.6 diopters more than centrifugal incisions.
authors.affiliation: Ophthalmology Research Laboratory, National Vision Research Institute, San Diego, Calif, USA.
authors.forename: G W
authors.initials: GW
authors.lastname: Flanagan
authors.forename: P S
authors.initials: PS
authors.lastname: Binder
mesh_terms: D006801:Humans; D007646:Keratotomy, Radial / Q000379:methods*; D012029:Refraction, Ocular; D012044:Regression Analysis; D012189:Retrospective Studies; D016896:Treatment Outcome; D014792:Visual Acuity / Q000502:physiology