Diabetic retinopathy is damage to the back of the eye (retina) caused by complications of diabetes, which can eventually lead to blindness. Diabetic retinpathy can develop in anyone who has type 1 diabetes or type 2 diabetes. The longer you have diabetes, and the less controlled your blood sugar is, the more likely you are to develop diabetic retinopathy.
As the condition progresses, diabetic retinopathy symptoms may include:
- Spots or dark strings floating in your vision (floaters)
- Blurred vision
- Fluctuating vision
- Dark or empty areas in your vision
- Vision loss
- Difficulty with color perception
Diabetic retinopathy usually affects both eyes.
Diabetic retinopathy may be classified as early or advanced, depending on your signs and symptoms.
Early diabetic retinopathy. This type of diabetic retinopathy is called nonproliferative diabetic retinopathy (NPDR). It’s called that because at this point, new blood vessels aren’t growing (proliferating). NPDR can be described as mild, moderate or severe. When you have NPDR, the walls of the blood vessels in your retina weaken. Tiny bulges (called microaneurysms) protrude from the vessel walls, sometimes leaking or oozing fluid and blood into the retina. As the condition progresses, the smaller vessels may close and the larger retinal vessels may begin to dilate and become irregular in diameter. Nerve fibers in the retina may begin to swell. Sometimes the central part of the retina (macula) begins to swell, too. This is known as macular edema.
Advanced diabetic retinopathy. Proliferative diabetic retinopathy (PDR) is the most severe type of diabetic retinopathy. It’s called proliferative because at this stage, new blood vessels begin to grow in the retina. These new blood vessels are abnormal. They may grow or leak into the clear, jelly-like substance that fills the center of your eye (vitreous). Eventually, scar tissue stimulated by the growth of new blood vessels may cause the retina to detach from the back of your eye. If the new blood vessels interfere with the normal flow of fluid out of the eye, pressure may build up in the eyeball, causing glaucoma. This can damage the nerve that carries images from your eye to your brain (optic nerve).
Complications can lead to serious vision problems including:
- Vitreous hemorrhage. The new blood vessels may bleed into the clear, jelly-like substance that fills the center of your eye. If the amount of bleeding is small, you might see only a few dark spots or floaters. In more-severe cases, blood can fill the vitreous cavity and completely block your vision. Vitreous hemorrhage by itself usually doesn’t cause permanent vision loss. The blood often clears from the eye within a few weeks or months. Unless your retina is damaged, your vision may return to its previous clarity.
- Retinal detachment. The abnormal blood vessels associated with diabetic retinopathy stimulate the growth of scar tissue, which can pull the retina away from the back of the eye. This may cause spots floating in your vision, flashes of light or severe vision loss.
- Glaucoma. New blood vessels may grow in the front part of your eye and interfere with the normal flow of fluid out of the eye, causing pressure in the eye to build up (glaucoma). This pressure can damage the nerve that carries images from your eye to your brain (optic nerve).
- Blindness. Eventually, diabetic retinopathy, glaucoma or both can lead to complete vision loss.
Tests and Diagnosis
Diabetic retinopathy is best diagnosed with a dilated eye exam. For this exam, your eye doctor will place drops in your eyes that make your pupils open widely. This allows your doctor to get a better view inside your eye. The drops may cause your close vision to be blurry until they wear off several hours later.
During the exam, your eye doctor will look for:
- Presence or absence of a cataract
- Abnormal blood vessels
- Swelling, blood or fatty deposits in the retina
- Growth of new blood vessels and scar tissue
- Bleeding in the clear, jelly-like substance that fills the center of the eye (vitreous)
- Retinal detachment
- Abnormalities in your optic nerve
In addition, your eye doctor may:
- Test your vision
- Measure your eye pressure to test for glaucoma.
As part of the eye exam, your doctor may do a retinal photography test called fluorescein angiography. First, your doctor will dilate your pupils and take pictures of the inside of your eyes. Then your doctor will inject a special dye into your arm. More pictures will be taken as the dye circulates through your eyes. Your doctor can use the images to pinpoint blood vessels that are closed, broken down or leaking fluid.
Optical coherence tomography
Your eye doctor may request an optical coherence tomography (OCT) exam. This imaging test provides cross-sectional images of the retina that show the thickness of the retina, which will help determine whether fluid has leaked into retinal tissue. Later, OCT exams can be used to monitor how treatment is working.
Treatment and Drugs
Treatment depends largely on the type of diabetic retinopathy you have. Your treatment will also be affected by how severe your retinopathy is, and how it has responded to previous treatments.
Early diabetic retinopathy
If you have nonproliferative diabetic retinopathy (NPDR), you may not need treatment right away. However, your eye doctor will closely monitor your eyes to determine if you need treatment.
It may also be helpful to work with your diabetes doctor (endocrinologist) to find out if there are any additional steps you can take to improve your diabetes management. The good news is that when diabetic retinopathy is in the mild or moderate stage, good blood sugar control can usually slow the progression of diabetic retinopathy.
Advanced diabetic retinopathy
If you have proliferative diabetic retinopathy, you’ll need prompt surgical treatment. Sometimes surgery is also recommended for severe nonproliferative diabetic retinopathy. Depending on the specific problems with your retina, options may include:
- Focal laser treatment. This laser treatment, also known as photocoagulation, can stop or slow the leakage of blood and fluid in the eye. It’s done in your doctor’s office or eye clinic. During the procedure, leaks from abnormal blood vessels are treated with laser burns. Focal laser treatment is usually done in a single session. Your vision will be blurry for about a day after the procedure. Sometimes you will be aware of small spots in your visual field that are related to the laser treatment. These usually disappear within weeks. If you had blurred vision from swelling of the central macula before surgery, however, you may not recover completely normal vision. But, in some cases, vision does improve.
- Scatter laser treatment. This laser treatment, also known as panretinal photocoagulation, can shrink the abnormal blood vessels. It’s also done in your doctor’s office or eye clinic. During the procedure, the areas of the retina away from the macula are treated with scattered laser burns. The burns cause the abnormal new blood vessels to shrink and scar. Scatter laser treatment is usually done in two or more sessions. Your vision will be blurry for about a day after the procedure. Some loss of peripheral vision or night vision after the procedure is possible.
- Vitrectomy. This procedure can be used to remove blood from the middle of the eye (vitreous) as well as any scar tissue that’s tugging on the retina. It’s done in a surgery center or hospital using local or general anesthesia. During the procedure, the doctor makes a tiny incision in your eye. Scar tissue and blood in the eye are removed with delicate instruments and replaced with a salt solution, which helps maintain your eye’s normal shape. Sometimes a gas bubble must be placed in the cavity of the eye to help reattach the retina. If a gas bubble was placed in your eye, you may need to remain in a facedown position until the gas bubble dissipates — often several days. You’ll need to wear an eye patch and use medicated eyedrops for a few days or weeks. Vitrectomy may be followed or accompanied by laser treatment.
- Eye Injections. Injection of medication into the vitreous fluid in the eye may be effective in treating wet macular degeneration, diabetic retinopathy and broken blood vessels within the eye. For example, to treat wet macular degeneration, periodic injections of medications directly into your eye may help stop disease progression. In some cases, this treatment may help to partially recover vision.
Surgery often slows or stops the progression of diabetic retinopathy, but it’s not a cure. Because diabetes is a lifelong condition, future retinal damage and vision loss are possible. Even after treatment for diabetic retinopathy, you’ll need regular eye exams. At some point, additional treatment may be recommended.