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

Abstract

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