Ability of Optical Coherence Tomography–determined Ganglion Cell Complex Thickness to Total Retinal Thickness Ratio to Diagnose Glaucoma

Abstract

Decreases in the G/T ratio occur during the early stages of glaucoma. When using SD OCT to diagnose glaucoma, the G/T ratio may improve the diagnostic ability of the macular parameter.

Comparison of macular ganglion cell complex thickness to total retinal thickness ratio between Hungarian and Japanese eyes

“…However, the relatively wide normal distribution of GCC thickness [21] may reduce its diagnostic accuracy. The new G/T ratio parameter reduces normal variability and increase the accuracy of glaucoma diagnostics, in Japanese eyes [26].…”

“…The goal of the current study was to investigate whether G/ T ratio, a parameter recently developed from GCC thickness and total macular retina thickness of the RTVue-100 OCT in Japanese eyes [26], is applicable to another ethnic group, European Caucasians. Asian eyes show several structural differences compared to Caucasian eyes [27][28][29][30][31], which may influence the clinical value of the OCT parameters even when highly myopic eyes are excluded from the analysis.…”

“…Total retinal thickness (thickness measured between the internal limiting membrane and the retinal pigment epithelium) and outer retinal (OR) thickness (thickness measured between the inner nuclear layer and the retinal pigment epithelium) were also measured, using the instrument's software. The G/T ratio was calculated using the following, published formula [26]: G/T ratio (%) = (GCC thickness/total retinal thickness) 9 100.…”

“…In healthy eyes GCC thickness varies between 76.6 and 119.8 lm [21], and is influenced by axial length, age and race [23][24][25]. In order to further improve the diagnostic ability of the inner macular thickness parameters of the RTVue-100 OCT, Kita and colleagues introduced a new parameter, the ratio of GCC thickness to total retinal thickness (G/T ratio) [26]. They found that G/ T ratio decreases already in the early stages of glaucoma, and the AUROC of the G/T ratio is significantly higher than circumpapillary RNFL thickness parameters in Japanese primary open angle glaucoma eyes [26].…”

“…In order to further improve the diagnostic ability of the inner macular thickness parameters of the RTVue-100 OCT, Kita and colleagues introduced a new parameter, the ratio of GCC thickness to total retinal thickness (G/T ratio) [26]. They found that G/ T ratio decreases already in the early stages of glaucoma, and the AUROC of the G/T ratio is significantly higher than circumpapillary RNFL thickness parameters in Japanese primary open angle glaucoma eyes [26]. Asian eyes, however, differ from those of other ethnic groups in several respects including disc size and axial length [27][28][29][30][31].…”