What Is Diabetic Retinopathy?

Diabetic retinopathy results from damage to blood vessels in the retina—the light-sensitive layer of tissue at the back of the eye. The condition is a complication of both type 1 and type 2 diabetes, and it can result in eyesight concerns ranging from blurriness to issues seeing colors and more. If untreated, blindness can occur.

Having poorly controlled levels of glucose (sugar) in the blood is a major risk factor for this condition, which is the most common cause of vision impairment and blindness among adults in the United States.

According to the National Eye Institute, more than 7 million Americans have diabetic retinopathy—a number that's expected to almost double by 2050. However, the Centers for Disease Control and Prevention (CDC) reports that 90% of blindness caused by diabetes is preventable.

Diabetic retinopathy results from damage to blood vessels in the retina.

Stages of Diabetic Retinopathy

Diabetic retinopathy affects both eyes, typically progressing through four distinct phases. Each is distinguished by the degree and type of damage to the retina.

Symptoms of Diabetic Retinopathy

In the early stages, diabetic retinopathy may produce few, if any, symptoms. As it progresses, issues with one's eyesight will arise and worsen if the condition is not treated. They can include:

• Floaters (specks, spots, dots, or other shapes that appear to be floating in the field of vision)
• Blurred vision
• Focus that goes in and out
• Impaired color vision
• Blockage of vision (usually due to a large hemorrhage inside the eye)
• Difficulty seeing at night
• Vision loss

Cause

Diabetic retinopathy occurs when blood glucose levels are not adequately controlled .

High levels of blood sugar (hyperglycemia) weaken blood vessels, causing fluid to leak into the retina and vitreous, and prompting new, weak blood vessels to grow.

Retinas depend on a rich supply of blood vessels. Without it, they cannot function as they should to absorb light and send signals through the optic nerve to the brain to be interpreted.

The longer a person has uncontrolled diabetes, the more likely they are to develop diabetic retinopathy.

Women with diabetes who become pregnant or who develop gestational diabetes are at increased risk, as are Latinx, Native American, and African-American people. Smoking also increases the risk of diabetic retinopathy.

Certain complications of diabetes are associated with the development of diabetic retinopathy as well—specifically, high blood pressure (hypertension) and high cholesterol.

Diagnosis

The only way to diagnose diabetic retinopathy is with a comprehensive eye examination. According to the National Eye Institute, of the several standard tests done during an eye exam, the ones that will help reach a diagnosis of diabetic retinopathy are:

• Visual acuity, which determines how well a person can see at various distances using an eye chart
• Tonometry, a measure of pressure inside the eye
• Retinal exam, in which drops are placed in the eye to cause the pupils to dilate, allowing the healthcare provider a clear view of the retina. They will be able to see changes to or leakage from blood vessels, warning signs of leaky blood vessels (such as fatty deposits), swelling of the macula, changes in the lens of the eye, and damage to nerve tissue.

Other tests sometimes performed if diabetic retinopathy is suspected or diagnosed include:

• Optical coherence tomography (OCT), a non-invasive imaging technology used to obtain high-resolution cross-sectional images of the retina 
• Fluorescein angiogram, in which a fluorescent dye injected into the bloodstream (usually through a vein in the arm) travels to the vessels in the retina. Pictures of the retina can then be taken and used to zero in on specific problem areas.

Treatment

How diabetic retinopathy is treated depends largely on what stage it has reached.

Early on, no treatment may be necessary aside from closely monitoring the health of the eyes and taking steps to improve how well diabetes is being managed. Improving blood sugar control often can slow the progression of damage to the retina.

If diabetic retinopathy reaches an advanced stage, however, any of a number of surgical procedures may be necessary right away.

These include:

• Photocoagulation: Also known as focal laser treatment, lasers are used to stop or slow leakage from abnormal blood vessels. This treatment—usually done in a healthcare provider's office or eye clinic—isn't likely to return blurry vision to normal, but it will help prevent it from worsening.
• Panretinal photocoagulation: This is another procedure that uses lasers to shrink abnormal blood vessels. Sometimes called scatter laser treatment, it can also be performed in a practitioner's office or eye clinic. It may lead to the loss of some peripheral or night vision.
• Vitrectomy: A tiny incision is made in the eye in order to remove blood from the vitreous as well as scar tissue that may be pulling on the retina. A vitrectomy is done in a surgery center or hospital using local or general anesthesia.
• Anti-VEGF therapy: This procedure involves the injection of medications called vascular endothelial growth factor (VEGF) inhibitors into the vitreous to help stop the growth of new blood vessels. VEGF inhibitors work by blocking the effects of growth signals the body sends to generate new blood vessels. Sometimes anti-VEGF therapy is used along with panretinal photocoagulation. While studies of anti-VEGF therapy in the treatment of diabetic retinopathy are promising, this approach is not yet considered standard.

A Word From Verywell

As with many complications of diabetes, it's entirely possible to head off diabetic retinopathy and other eye problems associated with the disease before measures such as surgery are needed.

The most effective thing you can do is manage your diabetes according to your healthcare provider's instructions. This involves eating healthfully, with an emphasis on foods that are low in carbs and calories and rich in nutrients; being physically active; kicking the habit if you smoke; monitoring your blood sugar regularly; and taking insulin or any medications you've been prescribed exactly as your practitioner tells you to.

You also should be proactive about your eye health: Get regular exams and if you notice any vision changes, see your eye doctor right away.