title: Multivariate Analysis of the Ocular Response Analyzer's Corneal Deformation Response Curve for Early Keratoconus Detection.
abstract: Purpose. To thoroughly analyze corneal deformation responses curves obtained by Ocular Response Analyzer (ORA) testing in order to improve subclinical keratoconus detection. Methods. Observational case series of 87 control and 73 subclinical keratoconus eyes. Examination included corneal topography, tomography, and biomechanical testing with ORA. Factor analysis, logistic regression, and receiver operating characteristic curves were used to extract combinations of 45 corneal waveform descriptors. Main outcome measures were corneal-thickness-corrected corneal resistance factor (ccCRF), combinations of corneal descriptors, and their diagnostic performance. Results. Thirty-seven descriptors differed significantly in means between groups, and among them ccCRF afforded the highest individual diagnostic performance. Factor analysis identified first- and second-peak related descriptors as the most variable one. However, conventional biomechanical descriptors corneal resistance factor and hysteresis differed the most between control and keratoconic eyes. A combination of three factors including several corneal descriptors did not show better diagnostic performance than a combination of conventional indices. Conclusion. Multivariate analysis of ORA signals did not surpass simpler models in subclinical keratoconus detection, and there is considerable overlap between normal and ectatic eyes irrespective of the analysis model. Conventional biomechanical indices seem to already provide the best performance when appropriately considered.
authors.affiliation: ECOS (Clinical Ocular Studies) Laboratory, Pueyrredón 1716, 1119 Buenos Aires, Argentina.
authors.forename: Jonatán D
authors.initials: JD
authors.lastname: Galletti
authors.affiliation: ECOS (Clinical Ocular Studies) Laboratory, Pueyrredón 1716, 1119 Buenos Aires, Argentina.
authors.forename: Pablo R
authors.initials: PR
authors.lastname: Ruiseñor Vázquez
authors.affiliation: ECOS (Clinical Ocular Studies) Laboratory, Pueyrredón 1716, 1119 Buenos Aires, Argentina.
authors.forename: Fernando
authors.initials: F
authors.lastname: Fuentes Bonthoux
authors.affiliation: ECOS (Clinical Ocular Studies) Laboratory, Pueyrredón 1716, 1119 Buenos Aires, Argentina.
authors.forename: Tomás
authors.initials: T
authors.lastname: Pförtner
authors.affiliation: ECOS (Clinical Ocular Studies) Laboratory, Pueyrredón 1716, 1119 Buenos Aires, Argentina ; Institute of Experimental Medicine, National Academy of Medicine/CONICET, Pacheco de Melo 3081, 1425 Buenos Aires, Argentina.
authors.forename: Jeremías G
authors.initials: JG
authors.lastname: Galletti