Diabetic Retinopathy: Causes, Symptoms, Diagnosis and Treatment

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By : Suvarna Sheth

Reviewed by: Qin Yang, M.D., Ph.D. 5/18.


Diabetic retinopathy is a diabetes complication that affects the eyes.  It’s caused by damage to the blood vessels of the light-sensitive tissue at the back of the eye, called the retina.

Symptoms of diabetic retinopathy may not be apparent immediately, but if diabetes is left uncontrolled, it can lead to blindness.  The condition can develop in anyone who has type 1 or type 2 diabetes.

Diabetic retinopathy is the most common cause of blindness among adults aged 20–74 years.

There are two types of diabetic retinopathy:

  • Non-proliferative diabetic retinopathy (NPDR):  The early stage of the disease in which symptoms will be mild or not apparent.  In this stage, small vessels in the retina are occluded, dilated or tortuous. This is accompanied by bleeding or fluid leakage to the retina, causing the retina to swell or to form deposits. However, no new blood vessels grow at this stage.
  • Proliferative diabetic retinopathy (PDR):  A more advanced form of the disease, characterized by new blood vessel growth in the retina. The new blood vessels are very fragile, easily damaged, causing bleeding in the retina or into eyes. Eventually, scar tissue forms, which may cause the retina to detach from the back of the eye. The optic nerve may also be damaged due to pressure build-up in the eyeball, resulting in glaucoma. The advanced diabetic retinopathy may develop in the setting of prior or coexisting early diabetic retinopathy. In some patients, advanced diabetic retinopathy may arise without early diabetic retinopathy.


Image courtesy: Shutterstock

 Causes of Diabetic Retinopathy

Diabetic retinopathy is caused because too much sugar in your blood causes the blood vessels in the retina to be blocked, cutting off blood supply.  As a result, the eye tries to re-grow blood vessels, but they don’t develop properly.

Besides having type 1 or type 2 diabetes, there are a few other risk factors associated with diabetic retinopathy including race, high cholesterol, and high blood pressure.  Women who are pregnant are also at greater risk for developing diabetes and diabetic retinopathy.

Symptoms of Diabetic Retinopathy

The symptoms of diabetic retinopathy may not be apparent early on, and the longer blood sugar levels are uncontrolled, retinopathy will worsen.  It will usually affect both eyes.  The symptoms include the following:

  • Spots, dark strings or spots floating in your vision
  • Blurry vision
  • Difficulty seeing properly
  • Dark areas in your vision
  • Vision loss

Diagnosis of Diabetic Retinopathy

Diabetic retinopathy is diagnosed with a comprehensive eye exam.  It will include a dilated eye exam involves having drops placed in the eyes so the pupils can widen, allowing your eye doctor can see inside your eyes.  He/she may also test your vision, for glaucoma and look for cataract.  During the exam, your doctor will look for the following:

  1. Blood vessels that are not normally developed
  2. Swelling, blood or fatty deposits in the retina
  3. New blood vessels growing
  4. Scar tissue
  5. Bleeding in the center of the eye
  6. A detachment of the retina
  7. Optic nerve abnormalities

You may have two other tests, called fluorescein angiography and optical coherence tomography.

Fluorescein angiography is a procedure which takes a picture inside your eye.  A special dye will also be injected into your arm and more pictures will be taken as the dye circulates through your eyes.  The pictures help the doctor see how if your blood vessels are healthy.

Optical coherence tomography is another exam that provides cross-sectional images of the retina that show how thick the retina is.  It is used to detect whether fluid has leaked into retinal tissue.

Treatment of Diabetic Retinopathy

Treating diabetic retinopathy will involve both diabetes management as well as seeing your ophthalmologist.  Two treatments for diabetic retinopathy are laser photocoagulation and vitrectomy.

Laser photocoagulation works by creating small burns that seal of leaking blood vessels.  The laser shrinks or destroys abnormal blood vessels in the retina.  The procedure is often done in an office or out-patient setting.

There are two types of laser surgery: In focal surgery — where the laser focuses on a small section of the retina.  Scatter treatment is another method which is used when leaking blood vessels cover a wider area of the retina.  In this procedure, the laser will make multiple burns.

Vitrectomy is a surgical treatment.  This could be an option if hemorrhaging doesn’t stop or if there is a retinal detachment.  It can also be an option if laser treatment was not successful.

During this procedure, the gel inside the eyeball is drained and replaced with new fluid.  Complications of the procedure may involve blurred vision, difficulty seeing in the dark, headache and bleeding.  The procedures cannot restore eyesight but can prevent further vision loss.

Medications can also be used to treat the swelling associated with diabetic retinopathy.  “anti-VEGF injection therapy” is one such therapy.  The drug is injected into the center of the eye to block a protein called vascular endothelial growth factor (VEGF), which can stimulate abnormal blood vessels to grow and leak fluid.

Initially, the injections would be required once a month, and then reduced depending on what your doctor thinks is best.  Steroid injections can also be used to reduce macular swelling.

What Can You do to prevent Diabetic Retinopathy

The first step to preventing diabetic retinopathy is to consistently manage your diabetes.  If you have diabetes, take active steps to control your blood sugar.

See an ophthalmologist regularly, they may be able to detect diabetic retinopathy in its early stages.  The best way to prevent vision loss is to treat retinopathy early.  Early detection of diabetic retinopathy can reduce the risk of developing the disease by 95%.

High blood pressure, cholesterol, and obesity also contribute to a person developing diabetic retinopathy, so make sure all of these conditions are separately treated.

Controlling your blood pressure, keeping your A1C levels down, quitting smoking, and maintaining healthy cholesterol levels can help to lower your risk of eye disease.

If your child has been diagnosed with diabetes, be sure to discuss his or eye health with an ophthalmologist as well.  Also, be sure to consult your doctor if you experience sudden or gradual vision loss.

Much research is underway across the country to detect, treat and prevent vision loss.  For example, the Diabetic Retinopathy Clinical Research Network conducts large multi-center trials to test new therapies for diabetic eye disease, and to compare different therapies.

Researchers at Caltech are also developing a new device that could one day prevent or slow the progression of diabetic retinopathy.  You can read the full story here.

Qin Yang, M.D., Ph.D., is an assistant professor of medicine, physiology, and biophysics at the Center for Diabetes Research in the Department of Medicine, Division of Endocrinology, at the UC Irvine School of Medicine.  He specializes in Endocrinology & Metabolism and Internal Medicine.


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