阿尔茨海默病患者的视网膜厚度定量分析

Quantitative analysis of retinal thickness in patients with Alzheimer’s disease

目的研究阿尔茨海默病(Alzheimer′s disease,AD)患者与认知正常的对照人群视网膜厚度的可能差异,以期为AD的辅助诊断提供一种简易、无创、客观的诊断方法。方法在自然瞳孔下,利用光学相干断层显像仪(OCT)对12例AD志愿者(AD组)以及11例认知正常的对照人群(对照组)进行视乳头旁以及黄斑区视网膜厚度检查,然后对两组人群的结果进行独立组t检验,对两组不同位点厚度中有统计学差异的因素进行多因素非条件logistic回归分析,绘制受试者工作特征(ROC)曲线对预测指标进行评估。结果与对照组比较,AD组鼻侧[(59.42±7.90)μm vs(88.18±9.43)μm,P<0.001]、鼻上方[(82.83±22.01)μm vs(118.09±20.53)μm,P=0.001]、颞上方[(116.83±25.46)μm vs(139.45±15.53)μm,P=0.02]以及鼻下方[(96.33±36.14)μmvs(124.45±20.63)μm,P=0.03]的视乳头旁神经纤维层厚度显著变薄,但两组研究对象黄斑部各分区的视网膜厚度差异无统计学意义(P>0.05)。Logistic回归分析显示,仅鼻侧视乳头旁神经纤维层厚度进入模型(P<0.001,R^2=0.671,B=-0.416,OR=0.660),以73.5μm为临界点诊断AD,其敏感度为90.9%,特异度为100%。结论相比认知正常人群,AD患者的黄斑部视网膜厚度尚未发现明显改变,但在视乳头旁多个位置出现视网膜神经纤维层厚度变薄,提示视乳头旁视网膜神经纤维层厚度变薄、尤其是鼻侧区域变薄是协助诊断AD患者的敏感指标,但其诊断临界值还有待更大样本的研究来确定。

Objective To evaluate the differences of retinal thickness between patients with Alzheimer′s disease(AD) and control subjects, aiming to provide a feasible, non-invasive and objective diagnostic technique for AD. Methods Peripapillary retinal nerve fiber layer(RNFL) thickness and macular retinal thickness were examined by optical coherence tomography(OCT) under natural pupil in 12 patients with AD and 11 healthy subjects. Independent t-test was used to compare the results between these two groups. Multi-variance logistics regression was further applied to analyze the differences with statistical significance and ROC curve was used to evaluate the sensitivity and specificity of the diagnostic technique. Results The peripapillary RNFL thickness in the nasal(59.42±7.90 μm vs. 88.18±9.43 μm, P<0.001), superior nasal(82.83±22.01 μm vs. 118.09±20.53, P=0.001), temporal superior(116.83±25.46 μm vs. 139.45±15.53 μm, P=0.02) and inferior nasal(96.33±36.14 μm vs. 124.45±20.63 μm, P=0.03) areas in the AD patients were found significantly thinner than those in healthy subjects. However, no differences of retinal thickness in macular subareas were found between these two groups. Only the nasal peripapillary RNFL thickness was included into the regression model(P<0.001, R^2=0.671, B=-0.416, OR=0.660). With a threshold of 73.5 μm, the sensitivity and the specificity of this diagnostic technique were 90.9% and 100%, respectively. Conclusion There is no difference of the retinal thickness in the macular areas between AD patients and healthy subjects. Nevertheless, AD patients are found to have significantly thinner RNFL thickness in several peripapillary areas. This indicates that the peripapillary RNFL thickness, especially the thickness of the nasal area, is a sensitive index to assist the diagnosis of AD. However, the specific diagnostic threshold still needs further investigation in larger sample size.