Which are the stages that are induced in diabetic retinopathy?

Many: Poorly controlled diabetics (and a few even with good control) can develop weakness of the blood vessels in the retina cause edema (fluid lead), vessel dilation, vessel leakage, hemorrhage into the center of the eye and in advanced stages scar tissue, vision loss and retinal detachment. Each case is individual and the earlier you see an ophthalmologist, the more likely to preserve vision.

See a retina special: Diabetes damages blood vessels in the retina causing bleeding and swelling (diabetic macular edema - dme): nonproliferative diabetic retinopathy. This is the most common kind and the kind that causes the most vision loss (from dme). When new abnormal blood vessels grow along the retina (proliferative), this can cause bleeding (vitreous hemorrhage), traction (retinal detachment), and/or glaucoma.