目的:评价GDx检测RNFL厚度各参数的敏感性,特异性,准确性,阳性预测值,阴性预测值,阳性似然比,阴性似然比;比较正常人和青光眼患者GDx各参数的不同;确定GDx参数对青光眼早期诊断最有价值的指标和GDx早期诊断青光眼的能力。方法:用GDx对94例188眼正常人和88例173眼青光眼患者RNFL进行检测。将青光眼患者按视野的平均缺损程度分为早、中晚期青光眼两组。用t-test和方差分析,比较正常人RNFL参数与早、中晚期青光眼的不同;绘制GDx参数ROC曲线,比较GDx参数中ROC曲线下面积的大小;用逐步判别分析确定GDx参数中对早期青光眼诊断最有意义的指标。结果:正常人94例,平均年龄为:41.7±8.5岁;青光眼(早、中晚期)患者平均年龄:52.8±14.6岁。早期青光眼122眼,中晚期青光眼51眼,视野平均缺损(meandefect,MD;Octopus1-2-3自动视野计测量)为-1.6～23.2dB。正常人RNFL各参数与各期青光眼患者比较差异有非常显著意义(P<0.01)。GDx的TSNIT参数的敏感性和特异性为:74.0%和74.0%,准确性:86.8%,阳性预测值:73.0%,阴性预测值:76.0%,阳性似然比:2.96,阴性似然比:0.33。SA参数的敏感性和特异性为:71.1%和84.6%,准确性为77.5%,阳性预测值:80.9%,阴性预测值:76.1%,阳性似然比:4.62,阴性似然比:0.34。IA参数的敏感性和特异性为:76.3%和82.4%,准确性:78.8%,阳性预测值:80.0%,阴性预测值:79.1%,阳性似然比:4.34,阴性似然比:0.35。NFI参数的敏感性和特异性为:80.3%和67.0%,准确性:73.4%,阳性预测值:69.2%,阴性预测值:78.8%,阳性似然比:2.43,阴性似然比:0.29。GDx的TSNIT和NFI两个参数综合评价的敏感性和特异性为:76.3%和74.0%,准确性:93.3%,阳性预测值:87.7%,阴性预测值:63.2%,阳性似然比:3.05,阴性似然比:0.32。GDx两个参数综合评价时,NFI+IA结合评价的敏感性最高(88.4%),特异性最高的是SA+IA(84.6%)。如果NFI+TSNIT+SA+IA综合评价其敏感性和特异性达最高,分别是86.7%和85.6%。在特异性相同的情况下,GDx诊断早期青光眼的敏感性为66.4%,准确性:58.5%,阳性预测值:92.0%,阴性预测值:77.5%,阳性似然比:2.56,阴性似然比:0.45。中晚期青光眼诊断的敏感性为:86.3%,准确性:77.4%,阳性预测值:48.4%,阴性预测值:95.3%,阳性似然比:3.45,阴性似然比:0.18。GDx的NFI≥20时,敏感性和特异性分别为78.3%和78.7%,准确性为78.7%,阳性预测值为77.3%,阴性预测值为80.0%,阳性似然比为3.68,阴性似然比为0.28。GDx的NFI≥23时,敏感性和特异性为75.1%和84.0%,准确性为79.8%,阳性预测值为81.3%,阴性预测值为74.9%,阳性似然比为4.69,阴性似然比为0.30。GDx的NFI≥27时,敏感性和特异性分别为64.7%和91.0%,准确性为35.7%,阳性预测值为86.8%,阴性预测值为73.7%,阳性似然比为7.19,阴性似然比为0.39。GDx各参数ROC曲线下面积分别为NFI:0.84,IA:0.79,TSNIT:0.78,SA:0.77,IES:0.76。通过逐步判别分析,筛选出NFI和IA对区分早期青光眼贡献最大(F检验:P<0.01),用IA和NFI进行分析,诊断早期青光眼的敏感性和特异性分别为:88.4%和74.6%。结论:GDx为临床上提供定量检测视网膜神经纤维层厚度参数;NFI和IA是区分正常人和早期青光眼最有效指标。GDx可有助于临床上青光眼的早期诊断。

AIM:To evaluate reliability and diagnostic value of retinal nerve fiber layer(RNFL) thickness by GDx measurements in the diagnosis of glaucoma, and to identify the most important RNFL thickness parameters of GDx for early glaucoma diagnosis with stepwise discrimination analysis, sensitivity, specificity, accuracy, positive predictive value, negative predictive value,positive likelihood ratio,negative likelihood ratio of RNFL parameters on glaucoma diagnosis. ·METHODS: This study included 94 normal subjects (188 eyes) and 88 glaucoma patients (173 eyes). Sensitivity was calculated for all glaucoma patients(173 eyes) and again for two separate subgroups: early glaucoma (n=122 eyes) and moderation or advanced glaucoma(n=51 eyes) according to the mean defect of visual field. Receive operating characteristic curves(ROC) of discrimination function were plotted.·RESULTS: The mean age of the normal subjects and patients with glaucoma were 41.7±8.8(ranged form 25 to 75) and 52.8±14.6 (ranged form 19 to 73), respectively. There were 47 males and 47 females in normal individuals and 37 males and 51 females in patients with glaucoma. Mean defect of visual field of patients with glaucoma was from -1.6 to 23.2dB (Octopus 1-2-3 automatic perimeter). There was significant difference between normal subjects and glaucoma patients in all parameters of RNFL with t-test and ANOVA (P<0.01). Using single GDx VCC value as a cut-off point, the sensitivity:74.0%, specificity: 74.0%, accuracy: 86.8%, positive predictive value: 73.0%, negative predic-tive value: 76.0%,positive likelihood ratio: 2.96,negative likelihood ratio: 0.33 for TSNIT; sensitivity: 71.1%, speci-ficity: 84.6%, accuracy: 77.5%, positive predictive value: 80.9%,negative predictive value:76.1%,positive likeli-hood ratio:4.62,negative likelihood ratio:0.34 for SA; sensitivity:76.3%, specificity:82.4%,accuracy:78.8%,positive predictive value:80.0%,negative predictive value:79.1%,positive likelihood ratio:4.34,negative likelihood ratio:0.35 for NFI. When using two GDx VCC values as cut-off point, the sensitivity: 76.3%, specificity 74.0%, accuracy: 93.3%, positive predictive value: 87.7%, negative predictive value: 63.2%,positive likelihood ratio: 3.05,negative likelihood ratio: 0.32 for TSNIT and NFI, sensitivity:83.8%, specificity 79.3%, accuracy: 80.8%, positive predictive value: 78.8%, negative predictive value: 84.2%,positive likelihood ratio: 2.43,negative likelihood ratio: 0.29 for NFI and SA; sensitivity:88.4%, specificity 79.3%, accuracy: 83.0%, positive predictive value: 80.0%, negative predictive value: 88.2%,positive likelihood ratio: 4.27,negative likelihood ratio: 0.15 for NFI and IA; sensitivity:79.2%, specificity 84.6%, accuracy: 81.3%, positive predictive value: 82.5%, negative predictive value: 84.6%,positive likelihood ratio: 5.14,negative likelihood ratio: 0.25 for SA and IA. sensitivity:86.7%, specificity 85.6%, accuracy: 85.4%, positive predictive value: 84.7%, negative predictive value: 87.5%,positive likelihood ratio: 6.02,negative likelihood ratio: 0.16 for the integral of NFI, TSNIT, SA and IA. Under the same specificity, the sensitivity of early glaucoma stage with GDx was 66.4%, accuracy: 58.5%, positive predictive value: 92.0%, negative predictive value: 77.5%,positive likelihood ratio: 2.56,negative likelihood ratio: 0.45. The sensitivity of modera-tion and advanced glaucoma stage with GDx was 86.3%, accuracy: 77.4%, positive predictive value:48.4%, negative predictive value: 95.3%,positive likelihood ratio: 3.45,negative likelihood ratio: 0.18. When the "cut-off" point of NFI≥20, the sensitivity was 78.3%, specificity: 78.7%, accuracy: 78.7%, positive predictive value: 77.3%, negative predictive value: 80.0%,positive likelihood ratio: 3.68,negative likelihood ratio: 0.28. When the "cut-off" point of NFI≥23, sensitivity was 75.1%, specificity: 84.0%, accuracy: 79.8%, positive predictive value: 81.3%, negative predictive value: 74.9%,positive likelihood ratio: 4.69,negative likelihood ratio: 0.30. When the "cut-off" value of NFI≥27, sensitivity was 64.7%, specificity: 91.0%, accuracy: 35.7%, positive predictive value: 86.8%, negative predictive value: 73.7%,positive likelihood ratio: 7.19,negative likelihood ratio: 0.39. The area under ROC curve of GDx parameter were: NFI: 0.84, IA:0.79, TSNIT: 0.78, SA: 0.77, ISE: 0.76, respectively. Among them, the NFI discriminated best. In general, the area under the ROC curve increased from early to moderate and advanced glaucoma. Using stepwise discrimination analysis, NFI and IA discriminated the best for detecting early glaucoma diagnosis (F test: P<0.01), sensitivity and specificity with IA and NFI were 88.4% and 74.6%, respectively.·CONCLUSION: GDx can provide quantitative para-meters for clinic detecting RNFL thickness; NFI and IA are the best discrimination indexes to distinguish normal subjects and patients with glaucoma. GDx is helpful for early glaucoma diagnosis in clinic practice.

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