title: Comparison of SRK/T and Haigis formulas for predicting corneal astigmatism correction with toric intraocular lenses.
abstract: OBJECTIVE
  To compare the accuracy of the SRK/T and Haigis formulas for predicting corneal astigmatism correction with a toric intraocular lens (IOL).
  
  
  METHODS
  Department of Ophthalmology, Korea University College of Medicine, Seoul, South Korea.
  
  
  METHODS
  Retrospective cross-sectional study.
  
  
  METHODS
  Eyes with an Acrysof toric IOL were enrolled in the study. The corneal plane effective cylinder power of toric IOLs (target induced astigmatism vector [TIA]) predicted by the SRK/T and Haigis formulas were compared with the cylindrical correction achieved postoperatively (surgically induced astigmatism vector [SIA]). The magnitude of error was defined as the difference between the magnitudes of the SIA and TIA. The median absolute magnitudes of error predicted by the SRK/T and Haigis formulas were compared. The median absolute errors predicted by the 2 formulas were also compared.
  
  
  RESULTS
  The mean postoperative SIA was 1.80 diopters (D) ± 0.55 (SD). The magnitude of error predicted by the SRK/T and Haigis formulas was 0.31 ± 0.40 D and 0.23 ± 0.40 D, respectively. The median absolute magnitude of error predicted by the Haigis formula was statistically significantly smaller than that predicted by the SRK/T formula (P < .001). The median absolute error predicted by the Haigis formula (0.35 D) was also statistically significantly smaller than that predicted by the SRK/T formula (0.43 D) (P = .003).
  
  
  CONCLUSIONS
  The Haigis formula was more accurate than the SRK/T formula not only in predicting the refractive outcome but also in predicting corneal astigmatism correction by toric IOLs.
  
  
  BACKGROUND
  No author has a financial or proprietary interest in any material or method mentioned.
authors.affiliation: From the Department of Ophthalmology, Korea University College of Medicine, Seoul, South Korea.
authors.forename: Youngsub
authors.initials: Y
authors.lastname: Eom
authors.affiliation: From the Department of Ophthalmology, Korea University College of Medicine, Seoul, South Korea.
authors.forename: Jong Suk
authors.initials: JS
authors.lastname: Song
authors.affiliation: From the Department of Ophthalmology, Korea University College of Medicine, Seoul, South Korea.
authors.forename: Yong Yeon
authors.initials: YY
authors.lastname: Kim
authors.affiliation: From the Department of Ophthalmology, Korea University College of Medicine, Seoul, South Korea. Electronic address: hyomkim@kumc.or.kr.
authors.forename: Hyo Myung
authors.initials: HM
authors.lastname: Kim
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D001251:Astigmatism / Q000175:diagnosis / Q000503:physiopathology / Q000601:surgery*; D003315:Cornea / Q000503:physiopathology*; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D019654:Lens Implantation, Intraocular; D007910:Lenses, Intraocular; D008297:Male; D008875:Middle Aged; D049451:Nomograms; D018918:Phacoemulsification; D019591:Pseudophakia / Q000503:physiopathology*; D012029:Refraction, Ocular / Q000502:physiology; D012189:Retrospective Studies; D014792:Visual Acuity / Q000502:physiology; D055815:Young Adult