title: Intraocular lens power calculation using the IOLMaster and various formulas in eyes with long axial length.
abstract: OBJECTIVE
  To evaluate the predictability of intraocular lens (IOL) power calculations using the IOLMaster (Carl Zeiss) and different IOL power calculation formulas in eyes with a long axial length (AL).
  
  
  METHODS
  Department of Ophthalmology, Far Eastern Memorial Hospital, Taipei, Taiwan.
  
  
  METHODS
  This study included 68 eyes with an AL longer than 25.0 mm that had phacoemulsification with IOL implantation. Preoperative AL and keratometric index measurements were obtained with the IOLMaster (Group 1) or, respectively, with applanation ultrasound and automatic keratometry (Group 2). The power of the implanted IOL was used to calculate the predicted postoperative spherical equivalence (SE) by various formulas: SRK/T, SRK II, and Holladay 1 (Groups 1 and 2) and Haigis (Group 1). The predictive accuracy of the formula was analyzed by comparing the mean difference between the actual and predicted postoperative SE; that is, the mean absolute error (MAE).
  
  
  RESULTS
  The mean AL was significantly longer in Group 1 than in Group 2 (P = .03). The MAEs calculated by the SRK/T, SRK II, and Holladay 1 formulas were comparable between the 2 groups (P>.05). The lowest MAE was obtained using the IOLMaster data in the Haigis formula (P<.05).
  
  
  CONCLUSIONS
  Although AL measured by the IOLMaster was longer than that measured by ultrasound, use of optical or ultrasound biometry data in the SRK/T, SRK II, and Holladay 1 formulas resulted in similar accuracy of IOL power prediction in eyes with higher myopia. The IOL power calculated using the Haigis formula predicted the best refractive outcome in long eyes.
authors.affiliation: Department of Ophthalmology, Far Eastern Memorial Hospital, Taipei, Taiwan. jiakangw@yahoo.com.tw
authors.forename: Jia-Kang
authors.initials: JK
authors.lastname: Wang
authors.forename: Chao-Yu
authors.initials: CY
authors.lastname: Hu
authors.forename: Shu-Wen
authors.initials: SW
authors.lastname: Chang
mesh_terms: D000465:Algorithms; D001699:Biometry; D003430:Cross-Sectional Studies; D005123:Eye / Q000000981:diagnostic imaging / Q000473:pathology*; D006801:Humans; D019654:Lens Implantation, Intraocular; D007910:Lenses, Intraocular; D008433:Mathematics; D055095:Optics and Photonics; D018918:Phacoemulsification; D012029:Refraction, Ocular / Q000502:physiology; D014463:Ultrasonography; D014792:Visual Acuity / Q000502:physiology