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A.A. Bonfioli, G. Wollstein, H. Ishikawa, B.L. Jones, M. Gabriele, W.D. Dilworth, Z. Eliash, R.J. Noecker, J.S. Schuman; Comparison of GDx VCC and ECC Scanning Laser Polarimetry With OCT and HRT . Invest. Ophthalmol. Vis. Sci. 2005;46(13):4814.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: GDx with enhanced corneal compensator (ECC) is a new iteration of the GDx with variable corneal compensator (VCC) which aim to improve the correction of the corneal polarization. This study evaluated the ability of GDx–VCC and ECC to distinguish between healthy, glaucoma suspect (GS) and glaucoma subjects, and compared their measurements with those obtained by other imaging modalities. Methods: : The study included 58 eyes of 44 subjects scanned with GDx–VCC, ECC, optical coherence tomography (OCT; StratusOCT) and Heidelberg retina tomograph (HRT; HRT II) within a 6 month interval. The comparisons included the following GDx parameters: nerve fiber indicator (NFI), TSNIT average, and typical scan score; OCT parameters: mean overall nerve fiber layer thickness (mNFL); HRT parameters: cup/disc area ratio, cup shape measure and Moorfields regression analysis. Diagnostic categorization for OCT and HRT into normal, borderline and abnormal results was based on their normative data. GDx was classified based on NFI: normal (<30), borderline (≥30 and <50) and abnormal (≥50). Results: Twenty seven glaucomatous eyes, 21 GS eyes and 10 healthy eyes were included in the study. In the comparison between GDx–VCC and ECC parameters, statistically significant differences (p<0.05) were found for all parameters except NFI. A significant difference was found with both devices for the comparison of the mean measurements between healthy and GS eyes and glaucoma eyes. The difference between healthy and GS was not significant. The correlation of ECC with other imaging devices was slightly better than the correlations with VCC except for the correlations between NFI and OCT. No significant differences were found between the correlations for VCC and ECC and the imaging devices. The agreement between the diagnostic classification of GDx and the other imaging modalities was similar for all parameters except for improved agreement between ECC and OCT mNFL. Conclusions: GDx–ECC provided significantly different results than those obtained by VCC and a slightly better agreement with other imaging devices. NFI showed inconsistent results that might reflect an inaccurate adjustment of the machine classifier in the ECC version. Support: NEI (RO1–EY13178, RO1–EY11289, P30–EY008098), Research to Prevent Blindness, Eye & Ear Foundation (Pittsburgh, PA)
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