In healthy eyes, there is no swelling in the retina’s blood vessels and no leaking of fluids.
During this stage, a few small bulges appear in the retina’s blood vessel walls. There are usually no visual symptoms.
In this stage, some blood vessels swell and start to leak. Also, a few blood vessels may develop an uneven shape, making them look like beads on a string. There are usually no visual symptoms.
This stage has more leakage of blood into the retina, and a number of blood vessels supplying oxygen and nutrients to the eye can also become blocked. The body starts to signal the need to grow new blood vessels to help. Visual symptoms may occur.
This stage happens when the retina starts growing new, fragile blood vessels that often bleed into the eye. Symptoms like dark spots are usually present, and permanent vision loss may occur.