title: Comparison of dual rotating Scheimpflug-Placido, swept-source optical coherence tomography, and Placido-scanning-slit systems.
abstract: OBJECTIVE
  To compare measurements of corneal indices using dual rotating Scheimpflug-Placido, swept-source optical coherence tomography (OCT), and Placido-scanning-slit systems.
  
  
  METHODS
  Kangbuk Samsung Hospital, Seoul, South Korea.
  
  
  METHODS
  Prospective evaluation of diagnostic tests.
  
  
  METHODS
  Corneal topography measurements were performed using dual rotating Scheimpflug-Placido (Galilei G2), swept-source OCT (Casia SS-1000), and Placido-scanning-slit (Orbscan IIz) systems. The intraclass correlation coefficients (ICCs) and Bland-Altman plots were used to evaluate the agreement between measurements.
  
  
  RESULTS
  Fifty post-refractive surgery eyes and 50 normal eyes were evaluated. The agreement in anterior keratometry and pachymetry between the 3 devices was high in both groups (ICC > 0.9). In both groups, the ICC values for posterior keratometry and eccentricity were high between the dual rotating Scheimpflug-Placido and swept-source OCT systems (ICC > 0.9) but not between the Placido-scanning-slit system and the other 2 systems. The Placido-scanning-slit system yielded much steeper values for posterior keratometry in both groups (P < .05). The ICC values for posterior corneal elevation were lower than 0.9 between all 3 devices. The dual rotating Scheimpflug-Placido and swept-source OCT systems showed relatively higher ICC values than the Placido-scanning-slit system in both groups. Maximum posterior elevations were highest with the Placido-scanning-slit system followed by the swept-source OCT system and then the dual rotating Scheimpflug-Placido system.
  
  
  CONCLUSIONS
  Anterior keratometry obtained using 3 devices showed high degrees of agreement. Posterior keratometry and eccentricity showed greater agreement between the dual rotating Scheimpflug-Placido and swept-source OCT systems than with the Placido-scanning-slit system. The dual rotating Scheimpflug-Placido and swept-source OCT systems were equivalent in detecting the shape of the cornea and could be considered interchangeable.
authors.affiliation: From Sungkyunkwan University School of Medicine (Lee, Choi), Kangbuk Samsung Medical Center, Department of Ophthalmology, Seoul, South Korea; the University of Rochester Medical Center School of Medicine (Yoon), Department of Ophthalmology, New York, New York, USA.
authors.forename: Yong Woo
authors.initials: YW
authors.lastname: Lee
authors.affiliation: From Sungkyunkwan University School of Medicine (Lee, Choi), Kangbuk Samsung Medical Center, Department of Ophthalmology, Seoul, South Korea; the University of Rochester Medical Center School of Medicine (Yoon), Department of Ophthalmology, New York, New York, USA. Electronic address: sashimi0@naver.com.
authors.forename: Chul Young
authors.initials: CY
authors.lastname: Choi
authors.affiliation: From Sungkyunkwan University School of Medicine (Lee, Choi), Kangbuk Samsung Medical Center, Department of Ophthalmology, Seoul, South Korea; the University of Rochester Medical Center School of Medicine (Yoon), Department of Ophthalmology, New York, New York, USA.
authors.forename: Geun Young
authors.initials: GY
authors.lastname: Yoon
mesh_terms: D000328:Adult; D003315:Cornea / Q000033:anatomy & histology* / Q000473:pathology*; D063171:Corneal Pachymetry / Q000295:instrumentation*; D048988:Corneal Surgery, Laser; D019781:Corneal Topography / Q000295:instrumentation*; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D049008:Keratectomy, Subepithelial, Laser-Assisted / Q000379:methods; D020731:Keratomileusis, Laser In Situ / Q000379:methods; D054018:Lasers, Excimer / Q000627:therapeutic use; D008297:Male; D011446:Prospective Studies; D015203:Reproducibility of Results; D041623:Tomography, Optical Coherence / Q000295:instrumentation*; D055815:Young Adult