Heidelberg Optical Coherence Tomography Applied For Measurement Of Retinal Nerve Fiber Layer Thickness In Normal Eyes Of Chinese People

Object: Optical Coherence Tomography(OCT) is such a technique with a high resolution, non-contact imaging of biological tissues, designed on optical coherence theory, which can in vivo acquire the cross sectional images of retinal and directly measure structural parameters. Since its inception OCT had been widely used clinically, including retinal nerve fiber layer thickness(RNFLT)measurement in the early diagnosis and follow-up of glaucoma. However, the normal range of RNFLT for Chinese population have not yet been established. The validity of current database provided by OCT may be subject to challenge and it is speculated that RNFLT measured by OCT for Chinese population might be different. In addition, a number of factors such as age, gender, right or left eye, optic disc size influence on RNFLT is not clear. This study was designed to associated with foreign reference values,report RNFLT values in normal Chinese people and to investigate the relationship between RNFLT and age,gender,right or left eye,optic disc size.With a view to provide clinical guidance for early diagnosis of glaucoma.Method:1 Subjects: 331 eyes of 172 normal Chinese people age 8 to 73 years old presenting to the Ophthalmology Clinic at the Department of ophthalmology,the Second Hospital of Hebei Medical University,from June in 2009 to March in 2011.The average age of those subjects is 41.81±1.21.2 Methods:After being inquired of medical history and receiving the routine examination of ophthalmology,we choose the volunteers who met the standards of being examined by OCT.2.1 The measurement of all participants was imaged on Heidelberg Spectralis OCT.RNFLT thickness around the disc was determined with 3.4mm diameter circling scan,and it was measured and analyzed with the analysis program in computer.9 parameters of RNFLT including the average thickness in the superior(S),nasal(N),inferior(I),temporal(T), NI,TI,TS,NS quadrant,the average thickness over all scanning test points(G). Horizontal and vertical diameter of optic disc were detemined with raster linear scan,the record were noted.3 The data was analayzed with SPSS 13.0 commercial statistical sostware.Results:1 The average RNFLT,horizontal and vertical diameter(HD,VD) of optic disc of the normal subjects were:N 75.46±15.20μm,I 139.33±19.02μm,NI 121.74±24.90μm,TI 157.48±20.76μm,T 80.54±12.81μm,TS 146.74±18.81μm,NS 121.71±23.68μm,S 133.93±17.35μm,G 107.62±10.60μm,HD 1.56±0.17mm,VD 1.74±0.17mm,respectively.2 According to foreign reference values:RNFLT of each quadrant and the average thickness over all scanning test points in normal Chinese people were significant higher than foreign reference values(P<0.01).3 According to different age groups: Six RNFLT parameters in total nine parameters including I, NI, TI, TS, S and G had statistically differences(P < 0.05). The six age group RNFLT curve of these six parameters except NI were in the shape of"M": the high points were 21 to 30 and 41 to 50 age group while the low points were≤20, 31 ~ 40 and 61 to 73 age group. The≤20 and 61 ~ 73 age group had lower set of values among these three low points.4 According to different genders: RNFLT of each quadrant and the average thickness over all scanning test points except temporal quadrant T were not correlated with gender.5 According to different right or left eye:Two RNFLT parameters in total nine parameters including NS and S had statistically differences(P < 0.05).6 According to the correlation between age and RNFLT:Negative correlations were found between age and TS ,TI (r=0.137,P=0.012和r=0.145,P=0.008).7 According to the correlation between HD,VD and RNFLT:Positive correlations were found between HD and N,I,T,S (P<0.05).Correlation coefficient were respective 0.215,0.158,0.252,0.189. Positive correlations were found between VD and I,T,S (P<0.05).Correlation coefficient were respective 0.214,0.117,0.240.Conclusion:1 RNFLT in normal Chinese population was measured by OCT. The reference value of each quadrant RNFLT and the average thickness over all scanning test points in normal Chinese people was listed in Table 1.2 Average RNFLT was mainly affected by ethnic,age and optic disc diameter,while the differences between gender and right or left eye and RNFLT was very slight.