Diabetic Retinopathy (DR) is a severe vision threatening disease which causes visual loss for most of diabetic eye disease patients. This paper presents an overview of various methods used by other researchers in determining the retina vascular tortuosity and its association with DR. In this paper, several quantitative methods of retinal vascular tortuosity in Retinopathy of Premature (ROP) assessment are included as a benchmark of tortuosity measurement in DR. Initial finding suggests that there is a possible association between retinal vascular tortuosity and the development of DR. To confirm this, further research has to be conducted to see the frequency or rate of retinal vascular tortuosity. As such, this paper intends to report the preliminary work conducted which summarizes several developments in recent literature and discusses the various methods used for tortuosity measurement in DR.