You are presented with multiple paper abstracts, alongside the associated literature review and chapter titles. Given the provided information, you are going to do a literature review. Please generate a coherent literature review that synthesizes the content, draws connections between different works, highlights major findings, and identifies any gaps in the existing research.

Literature Review Title: A Review on the Extraction of Quantitative Retinal Microvascular Image Feature 
Chapter Title:  Vessel Width Measuring Method. 
1. Abstract of Cited Paper (BIB001):  The retinal circulation is a potential marker of cerebral vascular disease because it shares origin and drainage with the intracranial circulation and because it can be directly visualized using ophthalmoscopy. Cross-sectional and cohort studies have demonstrated associations between chronic retinal and cerebral vascular disease, acute retinal and cerebral vascular disease, and chronic retinal vascular disease and acute cerebral vascular disease. In particular, certain qualitative features of retinopathy, retinal artery occlusion, and increased retinal vein caliber are associated with concurrent and future cerebrovascular events. These associations persist after accounting for confounding variables known to be disease-causing in both circulations, which supports the potential use of retinal vasculature findings to stratify individuals with regards to cerebral vascular disease risk.

Literature Review:
As the retinal microvascular sign for predicting the stroke possibility, artery and vein diameter were widely examined to obtain more accurate measurement system and, at the very beginning of this study, AVR or arteriolar Length to Diameter Ratio (LDR) has been normalized to compute artery and vein diameter. But Atherosclerosis Risk in Communities (ARIC) and Beaver Dam Eye Study (BDES) did not find any association with AVR or LDR and stroke. However, when the measurements of retinal vessel diameter have been normalized to optic nerve head diameter association with stroke was found. Central Retinal Artery Equivalent and Central Retinal Vein Equivalent were explored to meet the challenge raised in the study of retinal vascular dimension when retinal microvascular anatomy has been found different in different individuals BIB002 . Retinal vessel widening is a preindication of hypertensive retinopathy and researchers found there is an association with retinal vessel diameter and acute stroke BIB001 . Table 1 shows the association between retinal vessel diameter and stroke.