There are two main stages of diabetic retinopathy:

• non-proliferative and proliferative.
• proliferative diabetic retinopathy

In non-proliferative diabetic retinopathy, patients may have normal vision. The damaged retinal vessels leak fluid. Fat and protein particles may leak FROM these vessels and become deposited in the retina in patches known as retinal exudates. The retinal blood vessels may bleed INTO the retina and result in tiny hemorrhages. If any of the leaky fluid accumulates in the central part of the retina (called the macula), the vision is affected. This condition is called macular edema.

In proliferative diabetic retinopathy, patients grow new abnormal blood vessels that extend over the surface of the retina. These vessels occasionally invade the gelatinous contents of the eye, the vitreous. The proliferating blood vessels frequently break, causing vitreous bleeding that may significantly decrease vision. Fibrous tissue may grow over the new blood vessels and distort vision. Occasionally, the tissue may contract and pull the retina off the inner surface of the eye, causing a tractional retinal detachment.