Quantitative measurement of macular ganglion cell complex thickness by spectral domain optical coherence tomography

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Background Glaucoma is primarily characterized by the damage of retinal ganglion cells.The macular ganglion cell complex (GCC)thickness can be quantitatively measured using spectral domain optical coherence tomography(SD-OCT). Objective This clinical study was to explore the macular GCC thickness change in primary open-angle glaucoma (POAG) patient with SD-OCT. Methods A serial case-controlled study was designed.A total 101 eyes of 101 POAG patients and 41 normal eyes of 41 age- and refract power-matched normal subjects were cnrolled in the study.POAG patients were assigned to normal perimetry POAG group,early stage POAG group,advanced POAG group and late stage POAG group.Average macular GCC thickness(GCC-Avg),superior GCC thickness(GCC-Sup) and inferior GCC thickness (GCC-Inf)of subjects were measured by SD-OCT and compared among POAG patients and normal controls.Peripapillary retinal nerve fiber layer(RNFL) thickness was measured with time domain OCT(TD-OCT).The correlation between GCC thickness with RNFL thickness or mean deviation(MD) of perimetry were evaluated and analyzed.Informed consent was obtained from each patient prior to entering this study.Results GCC-Avg thickness,GCC-Sup thickness and GCC-Inf thickness were significantly decreased in the normalperimetry POAG group and early stage POAG group compared with the normal control group (GCC-Avg:t =5.411,10.247,P ＜ 0.01 ; GCC-Sup:t =6.171,9.484,P＜ 0.01 ; GCC-Inf:t =5.281,8.592,P ＜ 0.01 ).Also,GCC-Avg thickness,GCC-Sup thickness and GCC-Inf thickness were significantly decreased in the advanced POAG group compared with the early stage POAG group ( GCC-Avg:t =4.246,P＜0.01 ; GCC-Sup:t - 2.419,P - 0.019 ; GCC-Inf:t =4.636,P＜0.01 ),and GCC-Avg thickness,GCC-Sup thickness and GCC-Inf thickness were significantly decreased in the late stage POAG group compared with the advanced POAG group (GCC-Avg:t=2.095,P=0.040;GCC-Sup:t=2.756,P＜0.01:GCC-Inf:t =2.018,P =0.040 ).The positive correlations were seen between GCC-Avg thickness,GCC-Sup thickness,GCC-Inf thickness and RNFL-Avg thickness,RNFL-Sup thickness,RNFL-Inf thickness respectively( r =0.802,0.825,0.856,P ＜ 0.01 ).MD value of perimetry was positive correlated with GCC-Avg thickness in POAG patients ( r =0.601,P ＜ 0.01 ). Conclusions SD-OCT can quantitatively measure and differentiate the GCC thickness in POAG patients.The GCC thickness gradually decreases with the development of POAG.There exist a well correlation between visual field defect and RNFL thinning. Key words: Optical coherence tomography/spectral domain, time domain; Retina; Nerve fiber layer; Glaucoma