Diabetic retinopathy occurs when blood sugar levels are not managed effectively, damaging the blood vessels in your retina and prompting them to leak fluid. Your body tries to replace these damaged blood vessels by growing new ones. However, the new blood vessels are often irregular and weak. When they become damaged, they can very easily leak which leads to scar tissue, which, in turn, limits your vision.
When diabetic retinopathy becomes particularly severe, it may develop into diabetic macular edema. As the blood vessels in the retina continue to bleed, the retina starts to swell. Eventually, the retina can become so swollen that it obscures the macula, which is a small area of the retina responsible for your central vision, your ability to read, recognize faces, and notice fine details. Any damage to your macula can have a significant impact on your vision.