Scanning laser tomography in comparison to scanning laser polarimetry in glaucoma diagnostics
A. Mikowski, M. Lüchtenberg, R. Schalnus
Introduction: The confocal scanning laser tomography of the optic disc with the HRT II and the scanning laser polarimetry of the neuroretinal layer with the GDx are used in glaucoma diagnostics. Predictive values of both methods for detection of glaucomatous damage of the optic nerve are of great interest.
Patients and Methods: We examined 58 glaucoma patients and 38 healthy individuals with the confocal scanning laser system HRT II. In one randomised eye stereometric parameters of the optic disc were measured. Polarimetric measurements of the thickness of the neuroretinal layer were performed on 34 glaucoma patients and 25 healthy individuals with the scanning laser system GDx. For both systems we calculated sensitivity, specificity and the ROC-curve (receiver operator characteristics).
Results: The largest area under the ROC curve was found for the "rim value" (0.89), "cup shape measure" (0.89), and "cup/disc area ratio" (0.86).Those values were determined with the HRT II. All mean values in the glaucoma group were significantly different from those in the control group (p<0.05). The mean reference height of the measurements was 0.33+0,15 mm in the control group and 0,30+0,017 mm in the glaucoma group. For the neural network measure "the number", which was measured with the GDx, an area of 0.71 under the ROC-curve was found. The difference between glaucoma patients and healthy individuals was significant (p<0.05).
Discussion: The topographic parameters of the HRT II "rim value" and "cup shape measure" and the neural network measure of the GDx "the number" could detect a glaucomatous damage of the optic disc with reliability.
Zentrum der Augenheilkunde, Johann-Wolfgang-Goethe-Universität, Theodor-Stern-Kai 7, D - 60590 Frankfurt/Main