Purpose: The purpose of this project is to develop an index that can detect the presence or absence of a keratoconic pattern in corneal topography maps and find the location and measure the magnitude of the cone in patients with Keratoconus.
Methods: A software routine was written to extend the capabilities of The Ohio State University Corneal Topography Tool (OSUCTT), which is a software tool for processing topographic data. The routine finds the area-corrected average steepest 2mm diameter circle (C1) present on the map, with the center (P) of the circle being within the central 6mm. Then, the area-corrected average of all points outside of C1 is subtracted from the area-corrected average of all points inside of C1, resulting in M1. Next, the area-corrected average of the region (C2) 180 from P is found. The area-corrected average of all points outside of C2 is subtracted from the area-corrected average of all points inside of C2, resulting in M2. If P is outside of the central 2.5mm of the map then CLMI = M1-M2, otherwise CLMI = M1.
The radial and angular position and the magnitude of the cone are reported.
Results: For validation, 2 scans from 14 eyes of 7 normal subjects and 4 scans from 19 eyes of 14 subjects with clinically diagnosed Keratoconus were obtained on a TMS-1. All maps that could not be processed by the TMS-1 were excluded. Also, the Keratoconus Prediction Index (KPI) was recorded for each map from the TMS-1. Data generated by the TMS-1 were exported and processed through the OSUCTT to generate CLMI. A sensitivity/specificity analysis was performed on the data comparing KPI (30% threshold for disease) and CLMI to the presence or absence of Keratoconus. KPI had 100% specificity and 81.3% sensitivity, while CLMI produced a complete separation of data. Normals had a mean and standard deviation CLMI of 1.3D±0.8D and KPI of 2.1±-6.0. Diagnosed keratoconics had a mean CLMI of 10.1D±-4.4D and KPI of 66.4±-38.9.
Conclusions: CLMI provides a robust index that can detect the presence or absence of a keratoconic pattern in corneal topography maps. In addition, CLMI finds the location and magnitude of the cone in patients with Keratoconus.
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