Diabetic retinopathy is the leading cause of blindness in the United States in patients 20 to 74 years of age.  The two forms of diabetic retinopathy result when the abnormal blood vessels of the diabetic patient begin to leak or collapse.  Non-proliferative diabetic retinopathy occurs when blood vessels leak and fluid accumulates in the retina.  When the leakage is severe ("clinically significant macular edema"), laser surgery combined with injections of anti-inflammatory medications into the eye can be used to reduce or eliminate the associated retinal swelling.  Vision should stabilize with treatment, and in many cases can improve vision as well.

Proliferative diabetic retinopathy results from ischemia secondary to collapse or closure of blood vessels.  The retina eventually becomes sick and releases stimulants for the growth or "proliferation" of new blood vessels.  These new vessels are fragile and can easily bleed into the vitreous cavity causing severe loss of vision.  Laser surgery can drastically reduce the risk of severe vision loss in patients with proliferative diabetic retinopathy.  In some cases, severe hemorrhage or scar tissue develops leading to detachment of the retina.  This requires a special microsurgical procedure called vitrectomy in order to reattach the damaged retina.