One night while watching a play in a dark theater, Paula Lewis saw something terrifying: A fuzzy spot dancing in front of her eyes. She tried to tell herself it was a dustball, but she knew it was really a cloud of blood. Lewis had diabetes, a disease that can damage the blood vessels in the retina. Now one of her vessels had burst, and she worried that blindness wouldn't be far behind.
But Lewis didn't go blind. In fact, her vision is nearly as sharp as ever. Thanks to modern treatments, more and more people like Lewis are keeping their sight. If you have diabetes, you need to know that your vision could be in danger. You also need to know that there's plenty of room for hope.
What is diabetic retinopathy?
Diabetes can slowly damage many parts of the body, including the blood vessels that feed the retina, a paper-thin membrane in the back of your eye that collects light. If your blood sugar is too high for too long, the vessels can become fragile and leaky, and new vessels can appear where they don't belong. Doctors call this damage retinopathy, and it's the number-one cause of blindness in American adults.
At first, retinopathy usually has no symptoms. The vessels may balloon and form pouches, but you probably won't notice any changes in vision. This stage, called non-proliferative retinopathy, often doesn't require treatment. And in most cases, the condition goes into a holding pattern and never gets any worse.
If the damage continues, some vessels may become closed off, and new vessels will grow to take their place. This stage is called proliferative retinopathy. Unfortunately, the new vessels are usually weak and can easily burst. The resulting pools of blood can cloud your vision for days, months, or even years. The retina may also become scarred and detached from its blood vessels.
At any stage of the disease, fluid can leak onto the macula, the ultra-sensitive part of the retina that controls the sharpness and clarity of vision. This can cause swelling of the macula and blurring of vision.
Who is at risk for diabetic retinopathy?
Retinopathy is one of the most common complications of diabetes. Up to 45 percent of people with diabetes and 8 percent of people with pre-diabetes develop retinopathy. The problem is particularly common -- and particularly aggressive -- in people with poorly controlled blood sugar, high blood pressure, or nephropathy (kidney disease).
Retinopathy can also strike diabetic women during a pregnancy. Pregnant women with diabetes should have a retinal eye exam early in pregnancy to rule out existing retinopathy. If you already have retinopathy or another disease such as high blood pressure, check with your doctor to see how often you should have your eyes examined during pregnancy.
What are the symptoms of retinopathy?
Often, early retinopathy causes few or no symptoms. And by the time symptoms appear, the retina may already be significantly damaged. Even if you don't have symptoms, you should have your eyes checked by an experienced ophthalmologist at least once a year. (If you test normal, your doctor may examine your eyes every two to three years.) The specialist can check for retinopathy by dilating the pupil and examining the retina with a machine called an ophthalmoscope.
In another common test called a fluorescein angiography, or fluorescein dye test, an ophthalmologist injects a special dye into your arm. As the dye flows through your blood vessels into your retina, your ophthalmologist will look for any leaking blood vessels. Another test, the optical coherence tomography exam, shows how thick the retina is and whether fluid has leaked into it. To catch the condition as soon as possible, watch for these signs of trouble:
- Blurry vision
- Double vision
- Pain in one eye or both eyes
- Spots or floaters
- Fluctuating vision
- Distortion of straight lines
An ophthalmologist can also check for glaucoma and cataracts. These conditions are significantly more common in people with diabetes.
How is retinopathy treated?
Years ago, most people with diabetes who had retinopathy eventually went blind. But thanks to modern treatments, patients with severe retinopathy can reduce their risk of blindness by 95 percent. The advent of laser surgery was the biggest breakthrough in retinopathy treatment. Lasers can seal off the leaky vessels that cause macular edema, and they can also destroy the abnormal blood vessels that form in proliferative retinopathy.
A surgeon will aim the laser at the outer edges of your retina, so you may lose a little peripheral vision. In general, laser surgery won't improve your vision, but it can keep it from getting worse. If there's a lot of bleeding in your eye, your doctor may need to remove the excess fluid with an operation called a vitrectomy.
This operation works best if performed immediately after a vessel bursts. A doctor will make a tiny cut in the white of your eye and insert an instrument that sucks up the bloody fluid and replaces it with a saline solution. Your eye will be irritated, and you'll have to wear a patch for a few days.
Can retinopathy be prevented?
The best way to prevent retinopathy is to keep your blood sugar, blood pressure, and cholesterol under control. Not only will you protect your eyes, you'll also cut your risk of nerve damage, kidney disease, heart disease, and early death. Tight control isn't always easy, but it's within your reach. Work closely with your doctor, take your medications as directed, and make any recommended lifestyle changes. Your sight -- and your life -- may depend on it.
National Eye Institute. Diabetic Retinopathy. February 2008. http://www.nei.nih.gov/health/diabetic/retinopathy.asp
American Diabetes Association. Clinical Practice Recommendations 2009. Diabetes Care. Volume 32, Supplement 1. January 2009.
Greenstein VC, Holopigian K, Hood DC, Seiple W, Carr RE. The nature and extent of retinal dysfunction associated with diabetic macular edema. Invest Ophthalmol Vis Sci. 2000 Oct;41(11):3643-54.
Javitt JC. How often should patients with diabetes be screened for retinopathy? JAMA. 2000 Jul 26;284(4):437-8; discussion 439.
Murphy C, Newton W. How frequently should patients with type 2 diabetes mellitus be screened for retinopathy? J Fam Pract. 2000 May;49(5):395-6.
Diabetic Retinopathy. Diabetes Care 26:S99-S102, 2003.
Diabetic Retinopathy: What You Should Know. National Eye Institute. March 2004.
National Institutes of Health. Diabetic Retinopathy Occurs in Pre-Diabetes. June 2005. http://www.nih.gov/news/pr/jun2005/niddk-12.htm
National Eye Institute. Diabetic Retinopathy. April 2006. http://www.nei.nih.gov/health/diabetic/retinopathy.asp
Centers for Disease Control. National Diabetes Fact Sheet. January 2005. http://www.cdc.gov/diabetes/pubs/estimates.htm
American Diabetes Association. Clinical Practice Recommendations 2008. Diabetes Care. Volume 31, Supplement 1. January 2008. http://care.diabetesjournals.org/content/vol31/Supplement_1/
Mayo Clinic. Diabetic Retinopathy. February 2008. http://www.mayoclinic.com/health/diabetic-retinopathy/DS00447
Greenstein VC, Chen H, Hood DC, Holopigian K, Seiple W, Carr RE. Retinal function in diabetic macular edema after focal laser photocoagulation. Invest Ophthalmol Vis Sci. 2000 Oct;41(11):3655-64.