title: Corneal thickness and elevation measurements using swept-source optical coherence tomography and slit scanning topography in normal and keratoconic eyes.
abstract: BACKGROUND
  To compare corneal thickness and corneal elevation using swept source optical coherence tomography and slit scanning topography.
  
  
  METHODS
  Prospective study.
  
  
  METHODS
  41 normal and 46 keratoconus subjects.
  
  
  METHODS
  All eyes were imaged using swept source optical coherence tomography and slit scanning tomography during the same visit. Mean corneal thickness and best-fit sphere measurements were compared between the instruments.
  
  
  METHODS
  Agreement of measurements between swept source optical coherence tomography and scanning slit topography was analyzed. Intra-rater reproducibility coefficient and intraclass correlation coefficient were evaluated.
  
  
  RESULTS
  In normal eyes, central corneal thickness measured by swept source optical coherence tomography was thinner compared with slit scanning topography (p < 0.0001) and ultrasound pachymetry (p = < .0001). Ultrasound pachymetry readings had better 95% limits of agreement with swept source optical coherence tomography than slit scanning topography. In keratoconus eyes, central corneal thickness was thinner on swept source optical coherence tomography than slit scanning topography (p = 0.081) and ultrasound pachymetry (p = 0.001). There were significant differences between thinnest corneal thickness, and, anterior and posterior best-fit sphere measurements between both instruments (p < 0.05 for all). Overall, reproducibility coefficients and intraclass correlation coefficients were significantly better with swept source optical coherence tomography for measurement of central corneal thickness, anterior best-fit sphere and, posterior best-fit sphere (all p < 0.001).
  
  
  CONCLUSIONS
  Corneal thickness and elevation measurements were significantly different between swept source optical coherence tomography and slit scanning topography. With better reproducibility coefficients and intraclass correlation coefficients, swept source optical coherence tomography may provide a reliable alternative for measurement of corneal parameters.
authors.affiliation: Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Hong Kong.
authors.forename: Vishal
authors.initials: V
authors.lastname: Jhanji
authors.forename: Bingzhi
authors.initials: B
authors.lastname: Yang
authors.forename: Marco
authors.initials: M
authors.lastname: Yu
authors.forename: Cong
authors.initials: C
authors.lastname: Ye
authors.forename: Christopher K S
authors.initials: CK
authors.lastname: Leung
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D003315:Cornea / Q000473:pathology*; D019781:Corneal Topography / Q000379:methods*; D005260:Female; D006801:Humans; D007640:Keratoconus / Q000175:diagnosis*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D011446:Prospective Studies; D015203:Reproducibility of Results; D041623:Tomography, Optical Coherence / Q000379:methods*; D055815:Young Adult
keywords: corneal topography; keratoconus; topography