title: Simulation of machine-specific topographic indices for use across platforms.
abstract: OBJECTIVE
  The objective of this project is to simulate the current published topographic indices used for the detection and evaluation of keratoconus to allow their application to maps acquired from multiple topographic machines.
  
  
  METHODS
  A retrospective analysis was performed on 21 eyes of 14 previously diagnosed keratoconus patients from a single practice using a Tomey TMS-1, an Alcon EyeMap, and a Keratron Topographer. Maps that could not be processed or that contained processing errors were excluded from analysis. Topographic indices native to each of the three devices were recorded from each map. Software was written in ANSI standard C to simulate the indices based on the published formulas and/or descriptions to extend the functionality of The Ohio State University Corneal Topography Tool (OSUCTT), a software package designed to accept the input from many corneal topographic devices and provide consistent display and analysis. Twenty indices were simulated. Linear regression analysis was performed between each simulated index and the corresponding native index. A cross-platform comparison using regression analysis was also performed.
  
  
  RESULTS
  All simulated indices were significantly correlated with the corresponding native indices (p < 0.01), with a mean R of 0.84, ranging from 0.42 to 0.99. Cross-platform comparisons were nonsignificant for specific indices and devices.
  
  
  CONCLUSIONS
  Topographic indices native to three devices were successfully simulated. Cross-platform comparisons may be limited for specific indices.
authors.affiliation: Department of Ophthalmology and Biomedical Engineering, The Ohio State University, Columbus, Ohio 43210, USA.
authors.forename: Ashraf M
authors.initials: AM
authors.lastname: Mahmoud
authors.forename: Cynthia
authors.initials: C
authors.lastname: Roberts
authors.forename: Richard
authors.initials: R
authors.lastname: Lembach
authors.forename: Edward E
authors.initials: EE
authors.lastname: Herderick
authors.forename: Timothy T
authors.initials: TT
authors.lastname: McMahon
mesh_terms: D003198:Computer Simulation; D003315:Cornea / Q000473:pathology*; D019781:Corneal Topography; D005500:Follow-Up Studies; D006801:Humans; D007640:Keratoconus / Q000473:pathology*; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012984:Software