Figure 1. .

Retinal vascular competence grading system. Grade 0 = No vascular changes. All vessels are narrow and demonstrate a straight course. Grade 1 = Mild vascular changes. Vascular tortuosity is limited to slight undulations of a minority of vessels. Vascular dilation may be present, but involves large vessels alone, and small vessels are difficult to visualize. Grade 2 = Moderate vascular changes. Vascular tortuosity is present in the majority of vessels as obvious undulations. Vascular dilation is always present, and a few small vessels are clearly visible. The white spot about optic disc is a photographic artifact. Grade 3 = Severe vascular changes. Vascular tortuosity is present in the majority of vessels as obvious undulations. Vascular dilatation is extreme, and many small vessels are clearly visible. Grade 4 = Vitreous hemorrhage.