title: Complementary Keratoconus Indices Based on Topographical Interpretation of Biomechanical Waveform Parameters: A Supplement to Established Keratoconus Indices.
abstract: Purpose. To build new models with the Ocular Response Analyzer (ORA) waveform parameters to create new indices analogous to established topographic keratoconus indices.Method. Biomechanical, tomographic, and topographic measurements of 505 eyes from the Homburger Keratoconus Centre were included. Thirty-seven waveform parameters (WF) were derived from the biomechanical measurement with the ORA. Area under curve (ROC, receiver operating characteristic) was used to quantify the screening performance. A logistic regression analysis was used to create two new keratoconus prediction models based on these waveform parameters to resample the clinically established keratoconus indices from Pentacam and TMS-5.Results. ROC curves show the best results for the waveform parameters p1area, p2area,h1,h2, dive1, mslew1, aspect1, aplhf, and dslope1. The new keratoconus prediction model to resample the Pentacam topographic keratoconus index (TKC) was WFTKC= -4.068 + 0.002 × p2area - 0.005 × dive1 - 0.01 ×h1 - 2.501 × aplhf, which achieves a sensitivity of 90.3% and specificity of 89.4%; to resample the TMS-5 keratoconus classification index (KCI) it was WFKCI= -3.606 + 0.002 × p2area, which achieves a sensitivity of 75.4% and a specificity of 81.8%.Conclusion. In addition to the biomechanically provided Keratoconus Index two new indices which were based on the topographic gold standards (either Pentacam or TMS-5) were created. Of course, these do not replace the original topographic measurement.
authors.affiliation: Department of Ophthalmology, Saarland University Medical Centre, Kirrberger Strasse 100, Bldg. 22, Homburg, 66421 Saar, Germany.
authors.forename: Susanne
authors.identifier: 0000-0002-4791-2184
authors.initials: S
authors.lastname: Goebels
authors.affiliation: Department of Experimental Ophthalmology, Saarland University, Kirrberger Strasse 100, Bldg. 22, Homburg, 66421 Saar, Germany.
authors.forename: Timo
authors.identifier: 0000-0003-0661-6239
authors.initials: T
authors.lastname: Eppig
authors.affiliation: Institute for Medical Biometry, Epidemiology and Medical Informatics, Saarland University, Campus Homburg, Bldg. 86, Homburg, 66421 Saar, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Wagenpfeil
authors.affiliation: Department of Physical Sciences, Open University, Milton Keynes MK7 6AA, UK.
authors.forename: Alan
authors.initials: A
authors.lastname: Cayless
authors.affiliation: Department of Ophthalmology, Saarland University Medical Centre, Kirrberger Strasse 100, Bldg. 22, Homburg, 66421 Saar, Germany.
authors.forename: Berthold
authors.initials: B
authors.lastname: Seitz
authors.affiliation: Department of Experimental Ophthalmology, Saarland University, Kirrberger Strasse 100, Bldg. 22, Homburg, 66421 Saar, Germany.
authors.forename: Achim
authors.identifier: 0000-0001-9175-6177
authors.initials: A
authors.lastname: Langenbucher
mesh_terms: D019540:Area Under Curve; D001696:Biomechanical Phenomena; D003315:Cornea / Q000000981:diagnostic imaging; D016208:Databases, Factual; D003936:Diagnosis, Computer-Assisted / Q000379:methods*; D006801:Humans; D007640:Keratoconus / Q000000981:diagnostic imaging* / Q000473:pathology*; D012372:ROC Curve; D012016:Reference Values; D012044:Regression Analysis; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D012984:Software; D058067:Wavelet Analysis