title: Comparison of ocular aberrations measured by a Fourier-based Hartmann-Shack and Zernike-based Tscherning aberrometer before and after laser in situ keratomileusis.
abstract: OBJECTIVE
  To assess agreement between a Hartmann-Shack aberrometer (Wavescan) and a Tscherning aberrometer (Wavelight Allegro Analyzer) and their respective agreement with manifest refraction before and after laser in situ keratomileusis (LASIK).
  
  
  METHODS
  Stanford Eye Laser Center, California, USA.
  
  
  METHODS
  Prospective comparative observational study.
  
  
  METHODS
  Multiple readings were obtained both aberrometers preoperatively and 12 months after wavefront-guided LASIK. Sphere, cylinder, spherical equivalent (SE), defocus Z(2,0), astigmatism Z(2,2), spherical aberration Z(4,0), coma Z(3,1), trefoil Z(3,3), and total higher-order aberrations (HOAs) were compared using intraclass correlation coefficients (ICCs) (perfect agreement = 1; disagreement = 0).
  
  
  RESULTS
  In the 100 study eyes, preoperative agreement was good to excellent between the aberrometers for the parameters of defocus, astigmatism, and spherical aberration (ICC: 0.8, 0.9, and 0.7, respectively) but was poor for coma, trefoil, and total HOAs (ICC: 0.6, -0.2, and 0.4, respectively). At 12 months, ICCs worsened for all parameters (ICC: defocus = 0.6; astigmatism = 0.2; spherical aberration = 0.6; coma = 0.4; trefoil = -0.3; total HOAs = 0.4). Preoperative agreement of sphere, cylinder, and SE was good to excellent between the manifest refraction and both aberrometers (ICC Hartmann-Shack: 0.98, 0.95, and 0.97, respectively; ICC Tscherning: 0.97, 0.92, and 0.98, respectively). However, agreement was poor to fair between the manifest refraction and both aberrometers at 12 months (ICC Hartmann-Shack: 0.4, 0.1, and 0.4, respectively; ICC Tscherning: 0.03, 0.02, and 0.2, respectively).
  
  
  CONCLUSIONS
  Although some HOAs measured with both aberrometers agreed preoperatively, such agreement might not persist after LASIK. Spherocylinder measurements with both aberrometers seemed to agree closely with the manifest refraction before LASIK, but not at 12 months.
  
  
  BACKGROUND
  Dr. Manche has equity in Calhoun Vision, Inc., Krypton Vision, Seros Medical, LLC, and Veralas and is a consultant to Best Doctors, Gerson Lehrman Group.
authors.affiliation: From the Byers Eye Institute, Stanford University School of Medicine, Palo Alto, California, USA.
authors.forename: Christopher S
authors.initials: CS
authors.lastname: Sáles
authors.affiliation: From the Byers Eye Institute, Stanford University School of Medicine, Palo Alto, California, USA. Electronic address: edward.manche@stanford.edu.
authors.forename: Edward E
authors.initials: EE
authors.lastname: Manche
mesh_terms: D057128:Aberrometry / Q000295:instrumentation*; D000328:Adult; D057108:Corneal Wavefront Aberration / Q000175:diagnosis* / Q000503:physiopathology; D005260:Female; D005583:Fourier Analysis; D006801:Humans; D020731:Keratomileusis, Laser In Situ / Q000379:methods*; D054018:Lasers, Excimer / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D009216:Myopia / Q000503:physiopathology / Q000601:surgery*; D011184:Postoperative Period; D057234:Preoperative Period; D011446:Prospective Studies; D012029:Refraction, Ocular / Q000502:physiology; D014792:Visual Acuity / Q000502:physiology; D055815:Young Adult