Diabetic Retinopathy: Symptoms, Stages, and Complications

Diabetic retinopathy can cause vision changes, including trouble reading and difficulty with distance vision. Early in the disease, there may be no symptoms at all. As the disease progresses, other symptoms like blurred vision, dark floating spots, and streaks that look like cobwebs can occur.

In developed countries, the most severe symptom—vision loss and blindness—is the most frequent cause of new cases of blindness among adults ages 20 to 74. It is estimated that more than half of people with diabetes will develop some form of diabetic retinopathy over time.

This article looks at the stages, symptoms, and complications of diabetic retinopathy. It also discusses some of the steps that can be taken in order to prevent blindness related to this condition.

Stages

There are four stages of diabetic retinopathy:

• Mild nonproliferative diabetic retinopathy (NPDR): In this stage, there may be no symptoms. During this time, small areas of balloon-like swelling (microaneurysms) develop on the tiny vessels in the retina, the light-sensitive back layer of your eyeball. These may leak fluid into the retina.
• Moderate NPDR: As the disease progresses, more vessels that nourish and support the retina can become weak and blocked. They may also begin to swell and become distorted in size. The vessels can lose their ability to transport blood.
• Severe NPDR: In this stage, even more blood vessels become blocked. This further disrupts blood supply to areas in the retina. The body compensates for the disruption by signaling the retina to grow new blood vessels.
• Proliferative diabetic retinopathy (PDR): This is the most advanced stage of retinopathy. New blood vessels grow along the inside surface of the retina and into the vitreous gel, the fluid that fills the eye. These vessels are weak and do not work efficiently. This makes them more likely to leak and bleed. Scar tissue can cause the retina to detach from the eye.

The progression of retinopathy appears to depend on several factors, like how long you have had diabetes and how well your blood sugar is controlled. But symptoms invariably get worse over time.

Symptoms of Diabetic Retinopathy

As the condition progresses, you may experience:

• Fluctuating vision (focus that goes in and out)
• Impaired color vision
• Blurry vision
• Dark floating spots
• Difficulty seeing at night
• Streaks that look like cobwebs
• Eye pain and/or eye redness
• Sudden loss of vision, especially after coughing or sneezing
  

These symptoms typically affect both eyes. In the early stages, symptoms may come and go.

Diabetic retinopathy can lead to problems with central vision. Vision loss may begin as blurriness or double vision. You may also have blank spots in your vision.

Vision loss is the most serious symptom of diabetic retinopathy. Vision loss and blindness typically occur when less severe forms of retinopathy are not treated and a person has had uncontrolled blood sugars for a very long time.

Early detection and treatment can limit the potential for serious vision loss.

Complications

When diabetic retinopathy is left untreated, it can cause serious complications. The vision changes caused by this condition may not be reversible, so it is important to seek care before these complications occur.

Cataracts

Cataracts occur when the natural lens of your eyes becomes cloudy. In your eye, an enzyme converts sugars into a sugar alcohol called sorbitol. Excess sorbitol in the eye can make the lens cloudy. High blood sugar can also lead to swelling, which can also contribute to the formation of cataracts.

Cataracts are one of the most common eye complications of diabetes. Having diabetes makes you two to five times more likely to develop cataracts.

Older research suggests that cataract surgery may accelerate the progression of diabetic retinopathy, but the American Diabetes Association states that recent studies have not definitively shown this association.

Glaucoma

Glaucoma is an eye disease caused by increased pressure in the eye. The increase in pressure can affect the optic nerve and therefore increase the risk of vision loss. Primary open-angle glaucoma (POAG) is the most common type of glaucoma in people with diabetes.

When you have diabetes, new blood vessels that form on the retina can prevent fluids from draining out of the eye. This can cause the increase in eye pressure that leads to glaucoma. Glaucoma can cause loss of your peripheral (side) vision.

People with diabetes can also get a rare type of severe glaucoma called neovascular glaucoma. This type of glaucoma can cause permanent vision loss if it's not treated right away.

Diabetic Macular Edema (DME)

When fluid accumulates in the eye, it can lead to swelling or thickening of the macula, which is the center of the retina. This leads to a complication called diabetic macular edema (DME).

DME can happen at any stage of diabetic retinopathy. It may progress slowly and doesn't usually cause symptoms right away. When it does cause symptoms, they may include:

• Blurry vision
• Trouble focusing
• Reading difficulties
• Poor color vision

DME is the most common cause of vision loss in people with diabetic retinopathy.

Retinal Detachment

The growth of new blood vessels can cause scar tissue to develop in the retina. When the scar tissue shrinks, it can distort the retina and pull it out of place.

If a small portion of your retina is detached, you may not have symptoms. However, if a larger portion is detached, you may experience:

• An increase in floaters
• Flashes of light
• A dark shadow or “curtain” in the middle or sides of your eyes

Any symptoms of retinal detachment should prompt you to seek medical attention right away. This is considered a medical emergency and immediate treatment is needed to prevent further damage. Retinal detachment can cause permanent blindness.

Vitreous Hemorrhage

In people with diabetic retinopathy, the abnormal blood vessels in the eye can easily rupture and bleed. A vitreous hemorrhage happens when this blood leaks into the vitreous humor, the clear fluid in the center of your eye. The blood prevents light from reaching your retina. 

When you have a vitreous hemorrhage, you may have:

• Blurry vision that is worse in the morning
• Floaters
• Flashes of light

Vitreous hemorrhage usually requires laser treatment to stop the bleeding. In severe cases, the vitreous humor and surrounding membrane may need to be removed. 

Even after the bleeding is stopped, it may take a few weeks for vision to return. This is because it takes time for the body to remove the blood from the vitreous humor. 

Blindness

Certain complications of diabetic retinopathy can cause permanent vision loss or blindness. This includes retinal detachment, vitreous hemorrhage, and glaucoma. 

In the United States, roughly 2.2% of people with diabetes who are over the age of 45 have vision loss related to diabetic retinopathy.  Globally, diabetic retinopathy has caused blindness in about .8 million people.

Some types of vision loss related to diabetic retinopathy can be reversed with prompt treatment. Any incidence of vision loss should be seen by a healthcare provider right away.

When to See a Healthcare Provider

Because eye disease can begin before symptoms do, the American Diabetes Association recommends:

• All people newly diagnosed with type 2 diabetes receive an eye exam with dilation from an ophthalmologist or optometrist shortly after diagnosis and every year thereafter
• People with type 1 diabetes receive a dilated eye exam within five years of diagnosis and every year after that
• If there is no evidence of retinopathy for one or more annual eye exams, then exams every two years may be sufficient
• If there is evidence of retinopathy, more frequent exams will be necessary, preferably by an eye healthcare provider who understands and specializes in the management and treatment of diabetic retinopathy
  

When and how often you should go to the eye healthcare provider also depends on your glycemic control, if you are having symptoms, and your eye health. Parents of children with type 1 diabetes should ask their healthcare provider when and how often they need an eye exam.

People with preexisting diabetes (type 1 or 2) who are planning to get pregnant should discuss eye health with their healthcare provider, and they should have an eye exam before getting pregnant or within the first trimester of pregnancy.

When to Seek Immediate Care

If you are having any symptoms of visual impairment, such as an increase in blurriness, flashes of light, cloudiness, or vision loss, you should contact your healthcare provider right away for immediate care.

Retinal detachment is considered a medical emergency. You should see your healthcare provider or head to the emergency room if you have any symptoms. Early treatment could save your vision.

Summary

Diabetic retinopathy causes blood vessels in the eye to become blocked. Over time, the body tries to compensate by creating new, abnormal blood vessels. These blood vessels may leak and bleed, which can lead to problems with vision.

People with diabetic retinopathy are at higher risk for developing cataracts and glaucoma. Other potential complications include retinal detachment and vitreous hemorrhage. 

A Word From Verywell

Diabetic retinopathy can be treated effectively with early detection, screening, and treatment. People with diabetes can potentially prevent or delay retinopathy by keeping their blood sugar, lipid levels, and blood pressure under control.

There are different stages of retinopathy. In the earliest stage, you may not experience any symptoms. Therefore, it is important to have dilated eye exams and routine checkups when advised by your healthcare provider.