title: Use of Scheimpflug corneal anterior-posterior imaging in ray-tracing intraocular lens power calculation.
abstract: OBJECTIVE
  To examine improvement with the use of Scheimpflug imaging of the anterior and posterior corneal surfaces in the accuracy of ray-tracing intraocular lens (IOL) power calculation for normal cataractous eyes.
  
  
  METHODS
  Prospective case series comprised 136 eyes of 136 consecutive patients who had undergone cataract surgeries. Scheimpflug imaging of the cornea was included with routine preoperative examinations. Postoperative refractions were predicted using three methodologies; ray-tracing calculation using Scheimpflug imaging and Placido topography, ray-tracing calculations using Placido topography, and the SRK/T formula using autokeratometry. Prediction errors from the manifest refraction at 1 month postoperatively were compared between the methods. Influence of the posterior corneal curvature was also evaluated.
  
  
  RESULTS
  Mean prediction errors were 0.008, -0.103 and -0.042 D, respectively without significant difference between the three methods (p = 0.23). The prediction errors were significantly correlated with the posterior corneal curvature when the Scheimpflug imaging was not used (p < 0.03).
  
  
  CONCLUSIONS
  Use of Scheimpflug imaging in ray-tracing IOL power calculation was as accurate as the other calculations in normal cases, showing no bias in the posterior corneal curvature, as is the case with the other calculations.
authors.affiliation: Miyata Eye Hospital, Miyakonojo, Japan.
authors.forename: Kazunori
authors.initials: K
authors.lastname: Miyata
authors.forename: Shinichiro
authors.initials: S
authors.lastname: Otani
authors.forename: Naoto
authors.initials: N
authors.lastname: Honbou
authors.forename: Keiichiro
authors.initials: K
authors.lastname: Minami
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001699:Biometry / Q000379:methods; D003315:Cornea / Q000033:anatomy & histology*; D019781:Corneal Topography; D003952:Diagnostic Imaging / Q000379:methods*; D003941:Diagnostic Techniques, Ophthalmological; D005260:Female; D006801:Humans; D019654:Lens Implantation, Intraocular; D007910:Lenses, Intraocular; D008297:Male; D008875:Middle Aged; D055095:Optics and Photonics; D018918:Phacoemulsification; D011446:Prospective Studies; D012029:Refraction, Ocular / Q000502:physiology; D014792:Visual Acuity / Q000502:physiology
keywords: IOL power calculation; Scheimpflug imaging; posterior corneal curvature; ray tracing