title: Optical coherence tomography-based corneal power measurement and intraocular lens power calculation following laser vision correction (an American Ophthalmological Society thesis).
abstract: OBJECTIVE
  To use optical coherence tomography (OCT) to measure corneal power and improve the selection of intraocular lens (IOL) power in cataract surgeries after laser vision correction.
  
  
  METHODS
  Patients with previous myopic laser vision corrections were enrolled in this prospective study from two eye centers. Corneal thickness and power were measured by Fourier-domain OCT. Axial length, anterior chamber depth, and automated keratometry were measured by a partial coherence interferometer. An OCT-based IOL formula was developed. The mean absolute error of the OCT-based formula in predicting postoperative refraction was compared to two regression-based IOL formulae for eyes with previous laser vision correction.
  
  
  RESULTS
  Forty-six eyes of 46 patients all had uncomplicated cataract surgery with monofocal IOL implantation. The mean arithmetic prediction error of postoperative refraction was 0.05 ± 0.65 diopter (D) for the OCT formula, 0.14 ± 0.83 D for the Haigis-L formula, and 0.24 ± 0.82 D for the no-history Shammas-PL formula. The mean absolute error was 0.50 D for OCT compared to a mean absolute error of 0.67 D for Haigis-L and 0.67 D for Shammas-PL. The adjusted mean absolute error (average prediction error removed) was 0.49 D for OCT, 0.65 D for Haigis-L (P=.031), and 0.62 D for Shammas-PL (P=.044). For OCT, 61% of the eyes were within 0.5 D of prediction error, whereas 46% were within 0.5 D for both Haigis-L and Shammas-PL (P=.034).
  
  
  CONCLUSIONS
  The predictive accuracy of OCT-based IOL power calculation was better than Haigis-L and Shammas-PL formulas in eyes after laser vision correction.
authors.affiliation: Casey Eye Institute, Oregon Health & Science University, Portland, Oregon (Dr Huang, Dr Tang, Dr Zhang, Dr Armour, Dr Gattey, Dr Lombardi), and Cullen Eye Institute, Baylor College of Medicine, Houston, Texas (Dr Wang, Dr Koch).
authors.forename: David
authors.initials: D
authors.lastname: Huang
authors.forename: Maolong
authors.initials: M
authors.lastname: Tang
authors.forename: Li
authors.initials: L
authors.lastname: Wang
authors.forename: Xinbo
authors.initials: X
authors.lastname: Zhang
authors.forename: Rebecca L
authors.initials: RL
authors.lastname: Armour
authors.forename: Devin M
authors.initials: DM
authors.lastname: Gattey
authors.forename: Lorinna H
authors.initials: LH
authors.lastname: Lombardi
authors.forename: Douglas D
authors.initials: DD
authors.lastname: Koch
mesh_terms: D000368:Aged; D058452:Axial Length, Eye / Q000473:pathology; D003315:Cornea / Q000033:anatomy & histology / Q000502:physiology; D048988:Corneal Surgery, Laser; D005260:Female; D005583:Fourier Analysis; D006801:Humans; D019654:Lens Implantation, Intraocular; D007910:Lenses, Intraocular; D008297:Male; D008875:Middle Aged; D009216:Myopia / Q000503:physiopathology / Q000601:surgery*; D055095:Optics and Photonics; D018918:Phacoemulsification; D011237:Predictive Value of Tests; D011446:Prospective Studies; D041623:Tomography, Optical Coherence / Q000379:methods*