方法：计算机检索2016-01/2021-09 Embase、Pubmed、The Cochrane Library数据库关于AD患者黄斑区血流密度的相关研究，由两位研究员独立筛选文献、提取资料并采用纽卡斯尔-渥太华量表(NOS)评价纳入研究的偏倚风险，使用RevMan 5.3软件进行Meta分析。

结果：纳入10篇文献，共计研究对象740例(眼)，其中AD组321例，对照组419例(与AD组年龄相匹配且认知能力正常人群)。Meta分析结果显示，AD患者黄斑区浅层血流密度低于对照组(MD=-1.58，95%CI -2.60～-0.55，P=0.003)； AD患者黄斑区深层血流密度低于对照组(MD=-2.72，95%CI -4.36～-1.07，P=0.001)； AD患者旁中心凹血流密度低于对照组(MD=-1.44，95%CI -1.94～-0.94，P<0.00001)； AD患者中心凹无血管区面积略大于对照组(MD=0.05，95%CI -0.01～0.11，P=0.13)。

结论：AD患者黄斑区各分层血流密度均降低，OCTA可以辅助早期诊断AD。

METHODS: Embase, PubMed and Cochrane Library data were searched from January 2016 to September 2021 for relevant studies on vessel density in macular area of AD patients. Two researchers independently screened the literature, extracted the data, and evaluated the risk of inclusion bias using Newcastle-Ottawa Scale(NOS). Meta-analysis was performed using RevMan 5.3 software.

RESULTS: A total of 740 cases(eyes)were included in 10 literatures, including 321 cases from the AD group and 419 cases from the control group(age-matched people with normal cognitive abilities). The results of the Meta-analysis showed that the superficial vessel density in macular area of AD patients was lower than that in control group(MD=-1.58, 95%CI -2.60- -0.55, P=0.003). The deep vessel density in macular area of AD patients was lower than that in control group(MD=-2.72, 95%CI -4.36- -1.07, P=0.001). The parafoveal vessel density in AD patients was lower than that in control group(MD=-1.44, 95%CI -1.94- -0.94, P<0.00001). The avascular area in the fovea of AD patients was slightly larger than that of the control group(MD=0.05, 95%CI -0.01-0.11, P=0.13).

CONCLUSION: The vessel density of each layer in macular area of AD patients were lower than that of control groups the difference was statistically significant. OCTA can assist in the early diagnosis of AD.