title: Refractive error and visual outcome after cataract extraction.
abstract: OBJECTIVE
  To determine the range of biometry prediction error of the postoperative refraction and the visual outcome after cataract surgery.
  
  
  METHODS
  Postgraduate teaching hospital.
  
  
  METHODS
  Refraction and visual outcomes were recorded prospectively for a consecutive case series of 1817 cataract procedures. Complete preoperative and postoperative data were available for 1676 eyes (92.4%). The paired mean error of the difference between the predicted and achieved refraction, the percentages falling within +/-0.50 diopter (D), +/-1.00 D, and +/-2.00 D, and the values that contained 99% of data points were then calculated. The number that achieved a final Snellen visual acuity of 6/12 was determined in all eyes and in eyes without preoperative ocular comorbidity. This analysis was repeated in 1265 eyes that received a single intraocular lens (IOL) design (C10UB/C11UB) after phacoemulsification through a clear corneal incision.
  
  
  RESULTS
  The paired mean error of the difference between the predicted and achieved postoperative refraction in all eyes was -0.32 D +/- 1.05 (SD); 72.3% of eyes were within +/-1.00 D of the planned refraction, with bounds of 99% of observation of +2.92 D and -3.98 D. In the single IOL group, the paired mean error was -0.32 +/- 0.94 D; 74.2% of eyes fell within +/-1.00 D of the planned refraction, with bounds of 99% of observation of +2.54 D and -3.81 D. Axial length did not determine the magnitude of the biometry prediction error. At discharge from the service, 86.9% of all eyes and 95.4% of eyes without preoperative ocular comorbidity achieved a final corrected Snellen acuity of 6/12.
  
  
  CONCLUSIONS
  These data provide benchmark information that can be used to monitor clinical practice.
authors.affiliation: Moorfields Eye Hospital, 162 City Road, London EC1V 2PD, United Kingdom.
authors.forename: Christopher
authors.initials: C
authors.lastname: Murphy
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Tuft
authors.forename: Darwin C
authors.initials: DC
authors.lastname: Minassian
mesh_terms: D000368:Aged; D006784:Hospitals, Teaching; D006801:Humans; D019654:Lens Implantation, Intraocular; D018918:Phacoemulsification; D011446:Prospective Studies; D012029:Refraction, Ocular / Q000502:physiology*; D012030:Refractive Errors / Q000503:physiopathology*; D054140:Refractive Surgical Procedures; D016896:Treatment Outcome; D014792:Visual Acuity / Q000502:physiology*