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F.A. Medeiros, C. Bowd, L.M. Zangwill, R.N. Weinreb; Comparison of GDx VCC Scanning Laser Polarimeter, HRT II Confocal Scanning Laser Ophthalmoscope and StratusOCT Optical Coherence Tomograph for Glaucoma Detection . Invest. Ophthalmol. Vis. Sci. 2004;45(13):3409.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To compare the abilities of the newest commercially available versions of 3 optical imaging techniques – scanning laser polarimetry with variable corneal compensation (GDx VCC), confocal scanning laser ophthalmoscopy (HRT II – Heildelberg Retinal Tomograph) and optical coherence tomography (StratusOCT) to discriminate between healthy eyes and eyes with glaucomatous visual field loss. Methods: Seventy five patients with glaucomatous visual field loss and 66 healthy subjects with similar age were included in the study. All individuals underwent imaging with GDx VCC, HRT II and fast RNFL scan of the StratusOCT and visual field testing within a 6–month period. Average MD (± SD) of the visual field tests of glaucomatous patients was –4.87 ± 3.9 dB. Seventy percent of the patients had early glaucomatous visual field damage. ROC curves and sensitivities at fixed specificities (80% and 95%) were calculated for parameters reported as continuous variables on the clinical printout of each instrument. Diagnostic categorization (outside normal limits, borderline or within normal limits) provided by each instrument after comparison with their respective normative databases was also evaluated, and likelihood ratios (LRs) were reported. Results: No significant difference was found between the areas under the ROC curves (AUC) for the best parameters from the GDx VCC (Nerve Fiber Indicator, NFI – AUC = 0.91) and from the StratusOCT (RNFL inferior thickness – AUC = 0.92). The best HRT II parameter (cup/disc area ratio) had a significantly lower AUC (0.81) than the best parameters from GDxVCC and StratusOCT (P< 0.05). Abnormal results in each of the instruments, after comparison with their normative databases, were associated with strong positive LRs: 20.4 for abnormal GDx VCC (NFI>35 or any other parameter outside normal limits), 43.5 for an abnormal StratusOCT (any RNFL quadrant outside normal limits) and 19.4 for an abnormal HRT II (Moorfields regression analysis classification outside normal limits). Conclusions:Parameters reported as continuous variables had higher ROC curve areas for GDxVCC and StratusOCT than for HRT II. However, abnormal results (as compared to each instrument’s normative database) in all three instruments were associated with high LRs and large effects on posttest probabilities. Supported in part by the Foundation for Eye Research (FAM) and NEI Grant EY11008 (LMZ)
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