AIM: To explore the changes of retinal optical coherence tomography angiography(OCTA)vessel density in Patients with Alzheimer's disease(AD)by Meta-analysis, and to explore the value of OCTA in early diagnosis of AD patients.

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.