How does diabetic retinopathy develop from damage to retinal blood vessels?

Diabetic retinopathy develops when excess glucose circulating in the blood damages the small blood vessels within the retina. The progression of this condition typically occurs in two stages:12

• Nonproliferative Diabetic Retinopathy: In this early stage, damaged and weakened vessels begin to leak fluid into the retina, causing swelling and the formation of tiny aneurysms and small hemorrhages. Areas of the retina may also experience ischemia, where blood flow is restricted.32
• Proliferative Diabetic Retinopathy: If the condition advances, the retina may suffer from worsening blood flow. In response, the eye grows new, abnormal blood vessels on the retina, optic disk, or iris. These vessels are structurally unstable and fragile, making them highly susceptible to bleeding into the vitreous cavity. This process can lead to the formation of scar tissue, which may pull on the retina and result in retinal detachment or glaucoma.312