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Eric S Hwang, James Bradley Randleman; Comparative Analysis of Scheimpflug and SD-OCT Measurements in Patients With Highly Asymmetric Keratoconus. Invest. Ophthalmol. Vis. Sci. 2018;59(9):4397. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
To evaluate the efficacy of combining metrics from Scheimpflug and spectral domain optical coherence tomography (SD-OCT) imaging to distinguish normal eyes from the clinically unaffected eye from highly asymmetric keratoconic patients.
Measurements from 39 suspect keratoconic eyes (39 patients) and 63 healthy eyes (63 patients) were exported from Pentacam HR (Oculus, Inc.) Scheimpflug and Optovue (Optovue RT-Vue-100) SD-OCT devices. Evaluated Scheimpflug metrics included astigmatism, pachymetry, keratoconus screening indices, anterior curvature, cornea densitometry and ARTmax and BAD-D scores. Evaluated SD-OCT parameters included regional total corneal and epithelial thickness measurements. Significant metrics were evaluated individually with receiver operating characteristic curve analysis and in combinations using a binary logistic regression model.
Of the individual metrics that were significantly different between the two populations (p < 0.05), BAD-D and index of surface variation (ISV) had highest area under curve (AUC) values of 0.776 and 0.772 respectively. Among the SD-OCT metrics, epithelium standard deviation (EpiStd) and min-max (EpiMinMax) had highest AUC values with 0.715 and 0.724 respectively. When Scheimpflug metrics were combined in a logistic regression, highest AUC with minimal number of variables was 0.832 with the following variables: minimum thickness, index of vertical asymmetry (IVA) and index of height decentration. When SD-OCT values were combined, highest AUC with minimal variables was 0.942 with minimum thickness, min-median, EpiStd, EpiMinMax, and thickness in the superior, superonasal and temporal quadrants. The best results were obtained by combining Scheimpflug and SD-OCT metrics; the highest AUC with minimal variables was 0.956 with ISV, IVA, inferior-superior value from Scheimpflug and min-medium, EpiStd, EpiMinMax, and thickness measurements in the superior, inferotemporal and temporal regions from SD-OCT.
Individual metrics from both Scheimpflug and SD-OCT imaging poorly distinguished normal eyes from suspect keratoconic eyes. However, combination of anterior curvature indices from Scheimpflug, total and epithelial thickness metrics from SD-OCT strongly distinguished the two populations. The most significant metric categories were anterior curvature, epithelial thickness, and regional corneal thickness.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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