Accuracy of macular ganglion-cell complex thickness to total retina thickness ratio to detect glaucoma in white Europeans

PURPOSE: The aim of this study was to evaluate the diagnostic accuracy of macular ganglion-cell complex (GCC) thickness to total retinal thickness ratio (G/T ratio), a parameter found particularly accurate in Japanese eyes to detect glaucoma and recently proposed for the RTVue-100 Fourier-domain optical coherence tomography (RTVue-100 OCT), and to compare the diagnostic accuracy of this parameter to that of parameters provided by the instrument software in European eyes. METHODS: Retinal nerve fiber layer thickness (RNFLT) and macular GCC thickness parameters of 1 randomly selected eye of 177 white European patients (50 healthy, 28 ocular hypertensive, 33 preperimetric glaucoma, and 66 perimetric glaucoma eyes) were measured with an RTVue-100 OCT. RESULTS: The RNFLT and GCC parameter values of the healthy group were significantly higher than those of the various other groups (P<0.001 for all comparisons). For all separation (normal vs. all other eyes; normal vs. preperimetric and perimetric glaucoma eyes; and normal vs. perimetric glaucoma eyes) average RNFLT, inferior RNFLT, average GCC, and inferior GCC showed consistently higher area under receiver operating characteristics curve (AUROC) than G/T ratio. In the normal versus perimetric glaucoma separation, the AUROC values were 0.977, 0.982, 0.969, 0.976, and 0.959 for average RNFLT, inferior RNFLT, average GCC, inferior GCC, and G/T ratio, respectively. CONCLUSIONS: In contrast to Japanese eyes, in white Europeans G/T ratio does not improve separation of glaucomatous and healthy eyes.