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Jenny Ha, Joseph Mekhail, Sandra Lora Cremers, Jesus Alberto Martinez; Reproducibility and Reliability of a New Automated Scheimpflug Imaging Pterygium Severity Measure. Invest. Ophthalmol. Vis. Sci. 2017;58(8):1327.
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© ARVO (1962-2015); The Authors (2016-present)
To evaluate a recently reported automated pterygium severity measure of the distance of the leading edge of the pterygium head from the pupil center (DPC) by comparing values from measurements with Scheimpflug imaging (DPC-P; Pentacam, Oculus, Germany) and anterior segment optical coherence tomography (DPC-OCT; Heidelberg Engineering, Germany).
122 eyes of 116 patients’ Scheimpflug and anterior segment OCT scans were used to measure DPC three times by one rater. DPC-P measurements were automated by one click that provides Cartesian coordinates relative to the pupil center on the Pentacam elevation map. DPC-OCT measurements were made by selecting the OCT image with the most centrally extending hyper reflectivity and marking a best fit circle or ellipse around the pupil border. The pupil center was marked on the Heidelberg external photo image. Calipers were used to measure DPC-OCT from the most central aspect of the hyper reflectivity to the marked pupil center. Intraclass correlation coefficient was used to compare (1) individual DPC-P and DPC-OCT measurements which were performed three times each and (2) mean DPC-P and DPC-OCT measurements to each other. Pearson correlation assessed the relationship between DPC-P and DPC-OCT as continuous data. A p<0.05 was considered statistically significant.
The mean DPC-P and DPC-OCT were 3.20±0.70 mm and 3.22±0.78 mm, respectively. The mean difference between DPC-P and DPC-OCT was -0.017 mm. The intraclass correlation coefficients for the individual 3 DPC-P and 3 DPC-OCT were 95.2% (CI 93.6-96.5, p<0.001) and 96.3% (CI 95.1-97.3, p<0.001), respectively. The reliability between mean DPC-P and DPC-OCT was 92.8% (CI 89.7%-95.0%, p<0.001). DPC-P was significantly correlated with DPC-OCT (R=0.875, p<0.001).
DPC is a highly reproducible and reliable quantification of pterygium severity originally created using Scheimpflug imaging and is highly correlated to the in vivo DPC OCT measurements. Future studies will determine whether the microns of difference between DPC-P and DPC-OCT is clinically significant.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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