Diabetic retinopathy is the most common diabetic eye disease and leading cause of new-onset blindness in American adults. Between 40 to 45% of American’s diagnosed with diabetes have some stage of diabetic retinopathy, which causes 12,000 to 24,000 new cases of blindness each year.
Diabetic retinopathy is caused by changes in the blood vessels of the retina, the thin, light-sensitive inner lining in the back of your eye. This damage, called retinopathy, occurs to small blood vessels in the retina, which are easily harmed by high levels of glucose in the blood. How does diabetes damage the vessels in the retina? Recent research shows that diabetes affects the lining of the blood vessels, causing them to thicken and develop leaks. In addition, diabetes can make the vessels very weak. Also, poor circulation in the retinal vessels can lead to other complications, such as the growth of fragile new vessels.
There are two stages of diabetic retinopathy—an initial stage, which is called nonproliferative retinopathy, and a more serious stage called proliferative retinopathy, in which there is a greater risk of hemorrhage into the vitreous or detachment of the retina leading to severe vision loss. Another condition, called diabetic macular edema, can occur with either stage.
In the early nonproliferative stage, high levels of blood glucose cause damage to the blood vessels in the retina. They actually can leak fluid, which can collect and cause the retina to swell. If fluid collects in the central part of the retina (macular edema), blurred vision may occur. Macular edema can be treated with laser surgery when central vision is threatened.
A more dangerous stage of eye disease from diabetes is proliferative retinopathy. During this stage, abnormal blood vessels grow over the surface of the retina. These fragile blood vessels may rupture and bleed into the vitreous humor, the clear gel that fills the center of the eye. With vitreous hemorrhage, the blood blocks the passage of light to the retina and loss of vision or even blindness may occur. A further problem can occur when these blood vessels cause scar tissue, which may pull on the retina and cause it to become detached from the back of the eye. About half of the people with proliferative retinopathy also have macular edema. Proliferative diabetic retinopathy can also be treated with laser surgery to preserve vision and reduce the risk of severe vision loss to less than 5%. Additionally, vitreous hemorrhage that does not resolve, or scar tissue causing traction on the retina, can be removed by a surgical procedure called vitrectomy. Vitrectomy surgery can preserve vision and in many cases restore vision that has been lost due to vitreous hemorrhage.
Page last updated: July 28, 2015