What Is Diabetic Retinopathy? Symptoms and Causes

Diabetic retinopathy (DR) is an eye condition that affects people living with diabetes. It’s the leading cause of irreversible blindness in American adults. There are two main types of DR that cause a wide range of symptoms, from blurry vision to blindness. Understanding what diabetic retinopathy is, how it develops, and the symptoms you may experience can help you better learn how to manage and treat the condition.

Who Develops Diabetic Retinopathy?

According to the American Society of Retina Specialists, around 8 million people are living with DR in the United States. This number is expected to double by the year 2050.1 Nearly half of people with both type 1 diabetes (T1D) and type 2 diabetes (T2D) develop DR. The condition develops in both types of diabetes equally.2

People with diabetes who smoke, have high blood pressure, high cholesterol levels, or are pregnant are at higher risk of developing DR. Additionally, the longer you’ve been living with diabetes, the more your risk increases.

What Causes Diabetic Retinopathy?

Diabetic retinopathy is caused by changes in the blood vessels that provide oxygen and nutrients to the retina. It’s found at the back of the inner eye and is a light-sensitive tissue that helps create vision.

When people with diabetes have uncontrolled or high blood sugar levels, the blood vessels in the eyes become damaged.3 This may cause them to leak blood into the eye, leading to pressure and swelling. When there is swelling in the center of the eye, it’s known as diabetic macular edema. In more severe cases, new blood vessels form on the surface of the retina, which can create scarring.2

Symptoms of Diabetic Retinopathy

In the early stages of DR, many people don’t experience any symptoms. The condition only becomes more noticeable once it’s progressed further. With this, it’s important to go to your yearly eye exams so your eye doctor can monitor any issues with your eyes. This is especially true for anyone aged 50 or older.

Symptoms of DR can appear in one or both eyes. They include:3

  • Blurry vision
  • Double vision
  • Pressure or pain
  • Blank spots in your vision
  • Floating, dark spots (known as floaters)
  • Flashes of light
  • Rings in your vision

You may also notice that you have trouble reading or making your eyes focus. Your perception of color may also change.

Stages of Diabetic Retinopathy

There are two main stages of diabetic retinopathy — non-proliferative DR (NPDR) and proliferative DR (PDR).

NPDR is the early stage of the disease when you may notice very few symptoms. During this stage, the blood vessels around the retina begin to swell and leak. The nerve cells in the retina may also become damaged due to lack of oxygen and nutrients. This can lead to some vision problems. Diabetic macular edema may also develop during NPDR.

PDR is the late stage of the disease characterized by severe vision loss. During this stage, new blood vessels form around the retina, causing scarring. Blood may also leak into the vitreous, or the clear gel filling of the eyes. If there’s an increase in pressure in the eye, the optic nerve (which sends images from the eyes to the brain) can become damaged. A PDR diagnosis is serious and typically requires immediate treatment to help preserve any remaining vision.3,4

How Is Diabetic Retinopathy Diagnosed?

Diabetic retinopathy is diagnosed by your eye doctor, usually an optometrist or ophthalmologist. Optometrists can diagnose DR, but it’s typically treated by an ophthalmologist who specializes in retinal conditions. Diagnosing DR typically starts with a dilated eye exam. Your eye doctor will use eye drops to dilate (widen) your pupils to better look into your eyes.

During the eye exam, your eye doctor will look for signs of:2

  • Poor blood circulation to the retina, known as retinal ischemia
  • Swelling in the retina, known as diabetic macular edema
  • Development of abnormal blood vessels that may turn into PDR
  • Formation of new blood vessels on the retina, known as PDR

If you have any signs of diabetic retinopathy, your eye doctor will likely run some additional tests to confirm a diagnosis. These include taking photographs of your eyes using different instruments to look for abnormalities and measuring the intraocular pressure (pressure within your eyes).

Optical Coherence Tomography

Optical coherence tomography (OCT) is a test used to take pictures of your eyes. Specifically, the test takes cross-sectional images that help your eye doctor see the different layers of your retinas. They’ll then measure the thickness of the layers to help make a DR diagnosis.5

During an OCT exam, your eyes will be dilated, and you’ll sit at a machine with your chin on a rest. The machine will take pictures of your eyes for 5 to 10 minutes. Due to the dilation, your eyes will be sensitive to light for several hours after the exam.

Fluorescein Angiography

Fluorescein angiography (FA) uses a special dye and camera to take pictures of your retina. During the exam, your eyes will be dilated, and your eye doctor will inject a yellow dye (fluorescein) into a vein in your arm. The dye will circulate throughout your body for 10 to 15 seconds, including into the blood vessels in your eyes.6

Your eye doctor will then take pictures of your retinas as the dye flows through them, making them fluorescent. This helps them look for any abnormal blood vessels or blockages. Your eyes will be sensitive to light after the exam, and you may also experience blurry vision. Before having an FA, make sure to arrange a ride home, as it’s not safe to drive.


Tonometry is a test used to measure intraocular pressure. Your eye doctor may use eye drops to numb your eye, then use an instrument to touch the surface of your cornea (outer layer of the eye) to measure pressure. They may also use a machine that lets out a puff of air to flatten your cornea, and an instrument detects how much it flattens to measure pressure.7

Complications of Diabetic Retinopathy

If left untreated, DR may cause some eye complications. These include:8

  • Detached retina — caused by scar tissue from the growth of abnormal blood vessels pulling the retina away from the back of the eye; causes floaters or severe vision loss.
  • Vitreous hemorrhage — bleeding in the vitreous, which can cause floaters or complete loss of vision; this condition generally clears up on its own in a few weeks.
  • Glaucoma — caused by new blood vessels growing out of the retina and in front of the iris, blocking fluid drainage from the eye; this can cause vision loss.

Resources for Living with Diabetic Retinopathy

If you’re living with diabetic retinopathy, there are several resources available to help you live with vision loss, manage your diabetes, and connect with others with DR.