The diagnostic properties of a nerve-fiber analyzer in glaucoma: potential use as a screening or diagnostic tool

Methods: Patients with and without glaucoma underwent a complete eye evaluation, automated perimetry, scanning laser polarimetry with the GDx 400, and opticdisc photography. Two glaucoma experts graded each study eye. Two-by-two tables were constructed for 5 GDx parameters (average thickness, superior average, inferior average, ellipse average, and ellipse modulation) and the CDx number. Receiver operating characteristic (ROC) curves were generated. Results: The study included 355 patients (171 normal, 184 glaucoma). The mean values of the 5 GDx parameters were lower for the glaucoma than for the normal group. The sensitivity and specificity of the GDx 400 were 45.4 percent and 91.9 percent if the cut off level of the GDx number was 71. Ellipse modulation (EM) measures have the best ROC curve with area under the curve of 0.725. Conclusion: The GDx 400 nerve-fiber analyzer is primarily used as a screening tool to detect the presence or absence of glaucoma. Its accuracy can be improved with use of continuous corneal compensator.

Retinal nerve fiber measurements in glaucoma suspects

Purpose: To determine the proportion of glaucoma suspects with abnormal nerve fiber layer measurement using GDx nerve fiber analyzer Methodology: The study population consisted of glaucoma suspects between ages 30-70 years, who underwent glaucoma workup including retinal nerve fiber layer measurement (GDx NFA) Results: 35 eyes of glaucoma suspects were analyzed. 28/35 were found to have normal NFL thickness; 5/35 have 1 abnormal GDx parameters; 1/35 with 3 abnormal GDx parameters; 1/35 with 3 GDx abnormal parameters. Linear regression analysis showed no correlation between C:D and GDx parameters Conclusion: This study confirms that superior maximum is useful to the other parameters but there is a need to collect more samples. (Author)