title: Precision of higher-order aberration measurements with a new Placido-disk topographer and Hartmann-Shack wavefront sensor.
abstract: OBJECTIVE
  To assess the intrasession and intersession precision of ocular, corneal, and internal higher-order aberrations (HOAs) measured using an integrated topographer and Hartmann-Shack wavefront sensor (Topcon KR-1W) in refractive surgery candidates.
  
  
  METHODS
  IOBA-Eye Institute, Valladolid, Spain.
  
  
  METHODS
  Evaluation of diagnostic technology.
  
  
  METHODS
  To analyze intrasession repeatability, 1 experienced examiner measured eyes 9 times successively. To study intersession reproducibility, the same clinician obtained measurements from another set of eyes in 2 consecutive sessions 1 week apart. Ocular, corneal, and internal HOAs were obtained. Coma and spherical aberrations, 3rd- and 4th-order aberrations, and total HOAs were calculated for a 6.0 mm pupil diameter.
  
  
  RESULTS
  For intrasession repeatability (75 eyes), excellent intraclass correlation coefficients (ICCs) were obtained (ICC >0.87), except for internal primary coma (ICC = 0.75) and 3rd-order (ICC = 0.72) HOAs. Repeatability precision (1.96 × S(w)) values ranged from 0.03 μm (corneal primary spherical) to 0.08 μm (ocular primary coma). For intersession reproducibility (50 eyes), ICCs were good (>0.8) for ocular primary spherical, 3rd-order, and total higher-order aberrations; reproducibility precision values ranged from 0.06 μm (corneal primary spherical) to 0.21 μm (internal 3rd order), with internal HOAs having the lowest precision (≥0.12 μm). No systematic bias was found between examinations on different days.
  
  
  CONCLUSIONS
  The intrasession repeatability was high; therefore, the device's ability to measure HOAs in a reliable way was excellent. Under intersession reproducibility conditions, dependable corneal primary spherical aberrations were provided.
  
  
  BACKGROUND
  No author has a financial or proprietary interest in any material or method mentioned.
authors.affiliation: IOBA-Eye Institute, Valladolid, Spain.
authors.forename: Alberto
authors.initials: A
authors.lastname: López-Miguel
authors.forename: Loreto
authors.initials: L
authors.lastname: Martínez-Almeida
authors.forename: María J
authors.initials: MJ
authors.lastname: González-García
authors.forename: María B
authors.initials: MB
authors.lastname: Coco-Martín
authors.forename: Paloma
authors.initials: P
authors.lastname: Sobrado-Calvo
authors.forename: Miguel J
authors.initials: MJ
authors.lastname: Maldonado
mesh_terms: D057128:Aberrometry / Q000295:instrumentation*; D000328:Adult; D019781:Corneal Topography / Q000295:instrumentation*; D057108:Corneal Wavefront Aberration / Q000175:diagnosis*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D054140:Refractive Surgical Procedures; D015203:Reproducibility of Results; D055815:Young Adult