Study Of Using Optical Coherence Tomography To Measure Macular Ganglion Cell Complex Thickness In Early Primary Glaucoma Diagnosis

Objective Using 3D optical coherence tomography(3D OCT)to compare the difference between macular ganglion cell complex(mGCC)thickness parameters and peripapillary retinal never fiber layer(pRNFL)thickness parameters of normal and early primary glaucoma(EPG)patients,and analyze the diagnostic performances of the two kinds of parameters on EPG.Methods Thirty-one EPG cases(31 eyes)and 35 normal cases(35 eyes)were respectively collected as EPG group and normal group.Using OCT to measure and record the thickness parameters of mGCC and pRNFL.mGCC thickness parameters include the thicknesses of macular nerve fiber layer(mRNFL),ganglion cell layer plus the inner plexiform layer(GCIP),and ganglion cell complex(GCC)in superior,inferior,and average;pRNFL thickness parameters include the thicknesses of pRNFL in superior,nasal,inferior,temporal,and average.These parameters were followed every six months,totally three times.The data were analyzed statistically,i.e.,using two independent sample T test to compare the differences of mGCC and pRNFL thickness parameters between EPG and normal groups;taking Pearson correlation coefficient to assess the correlation between average mGCC thicknesses and average pRNFL thicknesses of EPG group;using area under receiver operating characteristic curve(AUROC)to evaluate the diagnostic efficacy of mGCC and pRNFL for EPG;using the random block design variance analysis to compare the variation of mGCC and pRNFL.Results All mGCC and pRNFL thickness parameters of EPG group were less than these in normal group.Except for temporal parameters(all P>0.05),there were significant differences between the thickness parameters of EPG and normal groups.The thicknesses in average of mRNFL,GCIP,GCC all correlated with thicknesses in average of pRNFL,and all these thickness parameters showed significant differences(all P < 0.05).There were no significant differences between pRNFL thicknesses in three follow ups,and between mGCC thicknesses in the first and the second follow ups(all P>0.05),while there showed significant differences between mGCC thicknesses in the third and the first,or the third and the second follow ups(all P<0.05).Take the first follow up for example,the AUROC of thickness parameters of mRNFL,GCIP,GCC in superior,inferior,and average were 0.698,0.645,0.682,0.706,0.768,0.771,0.776,0.749,0.791,respectively and the AUROC of thickness parameters of pRNFL in superior,temporal,inferior,nasal,and average were 0.808,0.732,0.841,0.622,0.836,respectively.Except for the pRNFL in temporal(P=0.0995),all the other parameters were able to discriminate EPG,with significant differences(all P<0.05).The AUROC of these parameters were close,and varied in the same direction with approximate amplitude in three follow ups,among which the AUROC of pRNFL in inferior was maxima(AUROC=0.901),and among those of mGCC parameters,the AUROC of GCC in average was maxima(AUROC =0.829).Conclusions The mGCC and pRNFL thickness parameters detected by 3D OCT show similar and stable diagnostic performance in EPG diagnosis.mGCC thickness parameters can be adopted as secondary indicators for diagnosing EPG,especially for recognizing changes of EPG in advance.