title: Evaluation of intereye corneal asymmetry in patients with keratoconus. A scheimpflug imaging study.
abstract: OBJECTIVE
  To assess the correlation between keratoconus severity and intereye asymmetry of pachymetric data and posterior elevation values and to evaluate their combined accuracy in discriminating normal corneas from those with keratoconus.
  
  
  METHODS
  This study included 97 patients: 65 subjects with bilateral normal corneas (NC) and 32 with keratoconus (KC). Central corneal thickness (CCT), thinnest corneal thickness (ThCT) and posterior elevation (PE) at the thinnest point of the cornea were measured in both eyes using Scheimpflug imaging. Intereye asymmetry and its correlation with keratoconus severity were calculated for each variable. The area under the receiver operating characteristic curve (AUROC) was used to compare predictive accuracy of different variables for keratoconus.
  
  
  RESULTS
  In normal eyes, intereye differences were significantly lower compared with the keratoconus eyes (p<0.001, for CCT, ThCT and PE). There was a significant exponential correlation between disease severity and intereye asymmetry of steep keratometry (r2 = 0.55, p<0.001), CCT (r2 = 0.39, p<0.001), ThCT (r2 = 0.48, p<0.001) and PE (r2 = 0.64, p<0.001). After adjustment for keratoconus severity, asymmetry in thinnest pachymetry proved to be the best parameter to characterize intereye corneal asymmetry in keratoconus. This variable had high accuracy and significantly better discriminating ability (AUROC: 0.99) for KC than posterior elevation (AUROC: 0.96), ThCT (AUROC: 0.94) or CCT (AUROC: 0.92) alone.
  
  
  CONCLUSIONS
  There is an increased intereye asymmetry in keratometry, pachymetry and posterior corneal elevation values in keratoconic patients compared to subjects with normal corneas. Keratoconus patients with more severe disease are also more asymmetric in their disease status which should be taken into account during clinical care.
authors.affiliation: Semmelweis University, Department of Ophthalmology, Budapest, Hungary.
authors.forename: Lóránt
authors.initials: L
authors.lastname: Dienes
authors.affiliation: Semmelweis University, Department of Ophthalmology, Budapest, Hungary.
authors.forename: Kinga
authors.initials: K
authors.lastname: Kránitz
authors.affiliation: Semmelweis University, Department of Ophthalmology, Budapest, Hungary.
authors.forename: Eva
authors.initials: E
authors.lastname: Juhász
authors.affiliation: Semmelweis University, Department of Ophthalmology, Budapest, Hungary.
authors.forename: Andrea
authors.initials: A
authors.lastname: Gyenes
authors.affiliation: Semmelweis University, Department of Ophthalmology, Budapest, Hungary.
authors.forename: Agnes
authors.initials: A
authors.lastname: Takács
authors.affiliation: Karl Landsteiner Institute of Process Optimalization and QM in Cataract Surgery, Vienna, Austria.
authors.forename: Kata
authors.initials: K
authors.lastname: Miháltz
authors.affiliation: Semmelweis University, Department of Ophthalmology, Budapest, Hungary.
authors.forename: Zoltán Z
authors.initials: ZZ
authors.lastname: Nagy
authors.affiliation: Semmelweis University, Department of Ophthalmology, Budapest, Hungary.
authors.forename: Illés
authors.initials: I
authors.lastname: Kovács
mesh_terms: D000328:Adult; D003315:Cornea / Q000002:abnormalities* / Q000033:anatomy & histology*; D019781:Corneal Topography; D005260:Female; D006801:Humans; D007640:Keratoconus / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D055815:Young Adult