title: Radial keratotomy clear zone diameter errors.
abstract: OBJECTIVE
  To examine the variability of achieved clear zone diameters following radial keratotomy and to determine if refractive outcomes are correlated to clear zone diameter errors.
  
  
  METHODS
  Twenty-six patients with radial keratotomy (51 eyes) were studied retrospectively. The central clear zone diameter for each radial incision meridian was measured using a slit-lamp and a photograph. The achieved clear zone diameters were statistically compared to the intended clear zone sizes and to the refractive outcomes.
  
  
  RESULTS
  Twenty-nine of the 51 eyes met various exclusion criteria. Ninety individual slit-lamp clear zone measurements were obtained for the remaining 22 eyes. Sixty-two of 90 (69%) achieved clear zone diameters were more than 0.25 mm different than the intended clear zone size. A maximum difference of +/- 0.80 mm from the intended clear zone marker size was observed. The average clear zone diameter error did not statistically differ between the three refractive outcome groups (undercorrection, emmetropia, and overcorrection).
  
  
  CONCLUSIONS
  In selected cases of centripetal radial keratotomy, the achieved clear zone diameter can vary widely from the intended clear zone size despite extensive surgeon experience.
authors.affiliation: Bascom Palmer Eye Institute, Palm Beach Gardens, FL 33418, USA.
authors.forename: M R
authors.initials: MR
authors.lastname: Grimmett
authors.forename: G S
authors.initials: GS
authors.lastname: Ogawa
mesh_terms: D003315:Cornea / Q000033:anatomy & histology* / Q000601:surgery; D005500:Follow-Up Studies; D006801:Humans; D007646:Keratotomy, Radial; D012029:Refraction, Ocular; D054140:Refractive Surgical Procedures; D015203:Reproducibility of Results; D012189:Retrospective Studies; D016896:Treatment Outcome