title: Evaluation of the diagnostic ability of vector parameters characterizing the corneal astigmatism and regularity in clinical and subclinical keratoconus.
abstract: OBJECTIVE
  To evaluate the diagnostic ability of the vector parameters ocular residual astigmatism (ORA), topography disparity (TD) and topographic astigmatism CorT (anterior and total) for the detection of clinical and subclinical keratoconus, and to develop a detection model based on them.
  
  
  METHODS
  This study comprised a total of 61 keratoconus eyes (KC group), 19 eyes with subclinical keratoconus (SKC group) and 100 healthy eyes (control group). In all cases, a complete eye exam was performed including an analysis of the corneal structure with the Sirius system (Costruzione Strumenti Oftalmici, CSO). Likewise, the iASSORT software (ASSORT Pty) was used to calculate in all cases the vector parameters ORA, TD and CorT.
  
  
  RESULTS
  Significant differences among groups were found in ORA, TD and CorT (anterior and total) (p<0.001). The diagnostic ability of ORA (cutoff 1.255 D, sensitivity/specificity 82%/92%) and TD (cutoff 1.035 D, sensitivity/specificity 78.5%/86%) for the detection of keratoconus was good, whereas anterior and total CorT showed a poorer diagnostic ability. ORA (cutoff 0.925 D, sensitivity/specificity 63.2%/77%) and TD (cutoff 0.710 D, sensitivity/specificity 74%/68%) showed an acceptable diagnostic ability for the detection of subclinical keratoconus, but anterior and total CorT did not. A detection model for subclinical keratoconus was obtained by logistic regression analysis involving TD, anterior corneal spherical aberration and posterior high order aberrations.
  
  
  CONCLUSIONS
  The vector parameters ORA and TD are useful for the diagnosis of clinical and subclinical keratoconus. In this last condition, the combination of TD with corneal aberrometric data provides a consistent detection model.
authors.affiliation: Group of Optics and Visual Perception, Department of Optics, Pharmacology and Anatomy, University of Alicante, Spain.
authors.forename: Antonio
authors.initials: A
authors.lastname: Martínez-Abad
authors.affiliation: Group of Optics and Visual Perception, Department of Optics, Pharmacology and Anatomy, University of Alicante, Spain; Department of Ophthalmology (OFTALMAR), VithasMedimar International Hospital, Alicante, Spain. Electronic address: david.pinyero@ua.es.
authors.forename: David P
authors.initials: DP
authors.lastname: Piñero
authors.affiliation: Department of Ophthalmology (OFTALMAR), VithasMedimar International Hospital, Alicante, Spain.
authors.forename: Pedro
authors.initials: P
authors.lastname: Ruiz-Fortes
authors.affiliation: Department of Ophthalmology (OFTALMAR), VithasMedimar International Hospital, Alicante, Spain.
authors.forename: Alberto
authors.initials: A
authors.lastname: Artola
mesh_terms: D000293:Adolescent; D000328:Adult; D001251:Astigmatism / Q000175:diagnosis*; D002648:Child; D003315:Cornea / Q000473:pathology; D019781:Corneal Topography / Q000379:methods*; D005260:Female; D006801:Humans; D007640:Keratoconus / Q000175:diagnosis*; D008297:Male; D008875:Middle Aged; D012372:ROC Curve; D012029:Refraction, Ocular; D012680:Sensitivity and Specificity; D014792:Visual Acuity
keywords: Corneal astigmatism; Keratoconus; Ocular residual astigmatism; Subclinical keratoconus; Topography disparity