Objective:To observe the morphological characteristics of retinal vessels in patients with ischemic stroke, and to preliminary analyze the correlation between retinal vascular morphological parameters and ischemic stroke.Methods:A retrospective study. From May 2015 to May 2017, 73 patients with ischemic stroke (ischemic stroke group) confirmed by examination at the Beijing Friendship Hospital, Capital Medical University were included in this study. In addition, 146 patients were included in the control group. A total of 146 patients with acute stroke who were excluded by head CT and/or magnetic resonance imaging were selected as the control group. Fundus images of patients were collected by nonmydriatic fundus camera. Retinal vascular parameters were measured by artificial intelligence fundus image analysis system, included retinal artery and vein caliber as well as vascular curvature, branching angle, fractal dimension, and density. The morphological characteristics of retinal vessels were compared between the control and ischemic stroke groups, and correlation between the retinal vascular parameters and ischemic stroke was analyzed using binary logistic regression.Results:Compared with the control group, the ischemic stroke group had thinner retinal artery caliber, smaller retinal vascular fractal dimension, and lower retinal vascular density; moreover, these differences were statistically significant ( t=3.232, 3.502, 3.280; P<0.05). Vascular fractal dimension [odds ratio ( OR)=0.291, 95% confidence interval ( CI) 0.160-0.528] and retinal artery caliber ( OR=0.924, 95% CI 0.870-0.981) were strongly correlated with ischemic stroke ( P<0.01). Conclusion:Compared with the control group, the retinal artery caliber, fractal dimension and retinal vascular density in ischemic stroke group are smaller; decreased retinal artery caliber and fractal dimension are correlated with ischemic stroke.

Objective:To analyze retinal vascular parameters and distribution characteristics in Chinese population via the fully automated quantitative measurement of retinal vascular morphological parameters based on artificial intelligence technology.Methods:A cross-sectional study was performed.A total of 1 842 patients without fundus diseases who visited Beijing Tongren Hospital from January 2011 to December 2021 were included.Standardized questionnaires, blood draws and ophthalmologic examinations of enrolled subjects were conducted.Color fundus photographs centered on the optic disk of one eye of patients were collected, and a deep learning-based semantic segmentation network ResNet101-Unet was used to construct a vascular segmentation model for fully automated quantitative measurement of retinal vascular parameters.The main measurement indexes included retinal vascular branching angle, vascular fractal dimension, average vascular caliber, and average vascular tortuosity.To compare different retinal parameters between sexes, the correlation between the above parameters and ocular factors such as best corrected visual acuity, intraocular pressure, and axial length, as well as systemic factors such as sex, age, hypertension, diabetes mellitus, and cardiovascular disease was analyzed.This study adhered to the Declaration of Helsinki.The study protocol was approved by the Ethics Committee of Beijing Tongren Hospital, Capital Medical University (No.20001220). Written informed consent was obtained from each subject.Results:The model established in this study achieved an accuracy over 0.95 for both vascular and optic disk segmentation.The vascular branching angle, vascular fractal dimension, average vascular caliber, and average vascular tortuosity were (51.023±11.623)°, 1.573(1.542, 1.592), 64.124(60.814, 69.053)μm, (0.001 062±0.000 165)°, respectively.Compared with females, males had larger vascular branching angle, smaller average vascular caliber and smaller vascular tortuosity, and the differences were statistically significant (all at P<0.05). The average vascular caliber increased by 1.142 μm in people with cardiovascular disease compared to people without cardiovascular disease ( B=1.142, P=0.029, 95% CI: 0.116-2.167). The average vascular tortuosity was positively correlated with hypertension ( B=3.053×10 -5, P=0.002, 95% CI: 1.167×10 -5-4.934×10 -5) and alcohol consumption ( B=1.036×10 -5, P=0.014, 95% CI: 0.211×10 -5-1.860×10 -5) and negatively correlated with hyperlipidemia ( B=-2.422×10 -5, P=0.015, 95% CI: -4.382×10 -5-0.462×10 -5). For each 1-mm increase in axial length, there was a decrease of 0.004 in vessel fractal dimension ( B=-0.004, P<0.001, 95% CI: -0.006--0.002), a decrease of 0.266 μm in the average vessel caliber ( B=-0.266, P=0.037, 95% CI: -0.516--0.016), and a decrease of -2.45×10 -5° in the average vessel tortuosity ( B=-2.45×10 -5, P<0.001, 95% CI: -0.313×10 -5--0.177×10 -5). For each 1.0 increase in BCVA, there was an increase of 3.992° in the vascular branch angle ( B=3.992, P=0.004, 95% CI: 1.283-6.702), an increase of 0.090 in vascular fractal dimension ( B=0.090, P<0.001, 95% CI: 0.078-0.102) and a decrease of 14.813 μm in the average vascular diameter ( B=-14.813, P<0.001, 95% CI: -16.474--13.153). Conclusions:A model for retinal vascular segmentation is successfully constructed.Retinal vessel parameters are associated with sex, age, systemic diseases, and ocular factors.