title: Subclinical keratoconus detection by pattern analysis of corneal and epithelial thickness maps with optical coherence tomography.
abstract: OBJECTIVE
  To screen for subclinical keratoconus by analyzing corneal, epithelial, and stromal thickness map patterns with Fourier-domain optical coherence tomography (OCT).
  
  
  METHODS
  Four centers in the United States.
  
  
  METHODS
  Cross-sectional observational study.
  
  
  METHODS
  Eyes of normal subjects, subclinical keratoconus eyes, and the topographically normal eye of a unilateral keratoconus patient were studied. Corneas were scanned using a 26,000 Hz Fourier-domain OCT system (RTVue). Normal subjects were divided into training and evaluation groups. Corneal, epithelial, and stromal thickness maps and derived diagnostic indices, including pattern standard deviation (PSD) variables and pachymetric map-based keratoconus risk scores, were calculated from the OCT data. Area under the receiver operating characteristic curve (AUC) analysis was used to evaluate the diagnostic accuracy of the indices.
  
  
  RESULTS
  The study comprised 150 eyes of 83 normal subjects, 50 subclinical keratoconus eyes of 32 patients, and 1 topographically normal eye of a unilateral keratoconus patient. Subclinical keratoconus was characterized by inferotemporal thinning of the cornea, epithelium, and stroma. The PSD values for corneal (P < .001), epithelial (P < .001), and stromal (P = .049) thickness maps were all significantly higher in subclinical keratoconic eyes than in the normal group. The diagnostic accuracy was significantly higher for PSD variables (pachymetric PSD, AUC = 0.941; epithelial PSD, AUC = 0.985; stromal PSD, AUC = 0.924) than for the pachymetric map-based keratoconus risk score (AUC = 0.735).
  
  
  CONCLUSIONS
  High-resolution Fourier-domain OCT could map corneal, epithelial, and stromal thicknesses. Corneal and sublayer thickness changes in subclinical keratoconus could be detected with high accuracy using PSD variables. These new diagnostic variables might be useful in the detection of early keratoconus.
  
  
  BACKGROUND
  Oregon Health and Science University (OHSU) and Drs. Li, Tan, and Huang have a significant financial interest in Optovue, Inc. These potential conflicts have been reviewed and managed by OHSU. Dr. Brass receives research grants from Optovue, Inc. Drs. Chamberlain and Weiss have no financial or proprietary interest in any material or method mentioned.
authors.affiliation: From the Center for Ophthalmic Optics and Lasers (Li, Chamberlain, Tan, Huang), Casey Eye Institute, and Department of Ophthalmology, Oregon Health and Science University, Portland, Oregon, the Brass Eye Center (Brass), Latham, New York, and the Gordon Weiss Schanzlin Vision Institute (Weiss), San Diego, California, USA. Electronic address: liyan@ohsu.edu.
authors.forename: Yan
authors.initials: Y
authors.lastname: Li
authors.affiliation: From the Center for Ophthalmic Optics and Lasers (Li, Chamberlain, Tan, Huang), Casey Eye Institute, and Department of Ophthalmology, Oregon Health and Science University, Portland, Oregon, the Brass Eye Center (Brass), Latham, New York, and the Gordon Weiss Schanzlin Vision Institute (Weiss), San Diego, California, USA.
authors.forename: Winston
authors.initials: W
authors.lastname: Chamberlain
authors.affiliation: From the Center for Ophthalmic Optics and Lasers (Li, Chamberlain, Tan, Huang), Casey Eye Institute, and Department of Ophthalmology, Oregon Health and Science University, Portland, Oregon, the Brass Eye Center (Brass), Latham, New York, and the Gordon Weiss Schanzlin Vision Institute (Weiss), San Diego, California, USA.
authors.forename: Ou
authors.initials: O
authors.lastname: Tan
authors.affiliation: From the Center for Ophthalmic Optics and Lasers (Li, Chamberlain, Tan, Huang), Casey Eye Institute, and Department of Ophthalmology, Oregon Health and Science University, Portland, Oregon, the Brass Eye Center (Brass), Latham, New York, and the Gordon Weiss Schanzlin Vision Institute (Weiss), San Diego, California, USA.
authors.forename: Robert
authors.initials: R
authors.lastname: Brass
authors.affiliation: From the Center for Ophthalmic Optics and Lasers (Li, Chamberlain, Tan, Huang), Casey Eye Institute, and Department of Ophthalmology, Oregon Health and Science University, Portland, Oregon, the Brass Eye Center (Brass), Latham, New York, and the Gordon Weiss Schanzlin Vision Institute (Weiss), San Diego, California, USA.
authors.forename: Jack L
authors.initials: JL
authors.lastname: Weiss
authors.affiliation: From the Center for Ophthalmic Optics and Lasers (Li, Chamberlain, Tan, Huang), Casey Eye Institute, and Department of Ophthalmology, Oregon Health and Science University, Portland, Oregon, the Brass Eye Center (Brass), Latham, New York, and the Gordon Weiss Schanzlin Vision Institute (Weiss), San Diego, California, USA.
authors.forename: David
authors.initials: D
authors.lastname: Huang
mesh_terms: D000328:Adult; D000368:Aged; D063171:Corneal Pachymetry; D003319:Corneal Stroma / Q000473:pathology*; D019781:Corneal Topography; D003430:Cross-Sectional Studies; D019573:Epithelium, Corneal / Q000473:pathology*; D005260:Female; D005583:Fourier Analysis; D064368:Healthy Volunteers; D006801:Humans; D007640:Keratoconus / Q000175:diagnosis*; D008297:Male; D008875:Middle Aged; D012372:ROC Curve; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D041623:Tomography, Optical Coherence; D055815:Young Adult