Discriminating between normal and glaucomatous eyes using the Heidelberg Retina Tomograph, GDx Nerve Fiber Analyzer, and Optical Coherence Tomograph

Objective: To compare the ability of 3 instruments, the Heidelberg Retina T omograph (HRT), the GDx Nerve Fiber Analyzer (GDx), and the Optical Coheren ce Tomograph (OCT), to discriminate between healthy eyes and eyes with earl y to moderate glaucomatous visual field loss. Subjects and Methods: Forty-one patients with early to moderate glaucomatou s visual field loss and 50 healthy subjects were included in the study. The HRT, GDx, and OCT imaging and visual field testing were completed on 1 eye from each subject within a 6-month interval. Statistical differences in se nsitivity at fixed specificities of 85%, 90%, and 95% were evaluated. In ad dition, areas under the receiver operating characteristic (RO C) curve were compared. Results: No significant differences were found between the area under the R OC curve and the best parameter from each instrument: OCT thickness at the 5-o'clock inferior temporal position (mean +/- SE, 0.87 +/- 0.04), HRT mean height contour in the nasal inferior region (mean +/- SE, 0.86 +/- 0.04), and GDx linear discriminant function (mean +/- SE, 0.84 +/- 0.04). Twelve H RT, 2 GDx, and 9 OCT parameters had an area under the ROC curve of at least 0.81. At a fixed specificity of 90%, significant differences were found be tween the sensitivity of OCT thickness at the 5-o'clock inferior temporal p osition (71%) and parameters with sensitivities less than 52%. Qualitative assessment of stereophotographs resulted in a sensitivity of 80%. Conclusion: Although the area under the ROC curves was similar among the be st parameters from each instrument, qualitative assessment of stereophotogr aphs and measurements from the OCT and HRT generally had higher sensitiviti es than measurements from the GDx.