Diagnostic value of thickness of macular ganglion cell complex and retinal nerve fiber layer measured by optical coherence tomography in patients with anterior ischemic optic neuropathy

Background Anterior ischemic optic neuropathy (AION) is a common eye disease, and early diagnosis is very important for reserving useful vision.Frequency-domain optical coherence tomography (FD-OCT) can display retinal microstructure in vivo and quantify the thickness of macular ganglion cell complex (GCC) and retinal nerve fiber layer (RNFL). Previous study on assessing retinal ganglion cell loss is assessed by measuring the RNFL thickness, while recent researches showed that GCC thickness measurement can reveal the retinal structure change in AION patients.However, there is few comparative studies on the diagnostic efficiency of RNFL thickness versus GCC thickness for AION. Objective This study was to evaluate and analyze the diagnostic value of GCC thickness and RNFL thickness measured by FD-OCT in patients with AION. Methods Fifteen eyes of 15 patients with AION and 14 normal eyes of 14 normal persons were enrolled in Eye Hospital of Tianjin Medical University from December 2013 to July 2014.Macular GCC thickness and disc RNFL thickness were measured by FD-OCT, and macular GCC thickness included superior, inferior and average GCC thickness around 6 mm×6 mm of macula, and focal loss volume (FLV) and global loss volume (GLV) were calculated.The disc RNFL thickness included superior, inferior and mean RNFL thickness around disc.The measuring outcomes between AION group and normal control group were compared.The diagnostic efficiency of GCC thickness and RNFL thickness was evaluated by the area under the receiver operating characteristic (ROC) curve. Results Compared with normal control group, the GCC thickness at superior, inferior and average GCC thickness at macula were thinner, with significant differences between them (t=-3.402, P=0.002; t=2.690, P=0.012; t=2.913, P=0.007). The FLV and GLV values were (8.39±4.54)μm3 and (19.57±10.66)μm3 in the AION group, which were significantly lower than (0.64±0.48)μm3 and (1.14±0.91)μm3 in the normal control group (t=5.036, 6.732; both at P<0.01). The disc RNFL thicknesses of superior, inferior and average RNFL were thinner in the AION group than those in the normal control group, with significant differences between them (t=2.815, P=0.009; t=2.392, P=0.024; t=2.863, P=0.008). The AUC of FLV and GLV for AION were both 1.000, and that of superior GCC thickness, inferior GCC thickness and average GCC thickness at macula was 0.871, 0.819 and 0.795, respectively.The AUC of average RNFL thickness and disc superior, inferior RNFL thicknesses for AION were 0.814, 0.809 and 0.762, respectively. Conclusions The diagnosis ability of GCC and RNFL thickness for AION is comparable.FLV and GLV appear to have the strongest efficiency in the evaluation of GCL in AION patients.Macular GCC measurement may provide a good alternative or a complementary practice to RNFL scans for the diagnosis of AION. Key words: Optic neuropathy, ischemic/diagnosis; Tomography, optical coherence; Retinal ganglion cells; Retina; Nerve fibers