Diabetic retinopathy is a potentially blinding complication of diabetes that damages the eye's retina. It affects half of all Americans diagnosed with diabetes.
Diabetic retinopathy occurs when diabetes damages the tiny blood vessels in the retina. At this point, most people do not notice any changes in their vision.
Some people with diabetic retinopathy develop a condition called macular edema. It occurs when the damaged blood vessels leak fluid and lipids onto the macula, the part of the retina that lets us see detail. The fluid makes the macula swell, blurring vision.
As the disease progresses, it enters its advanced, or proliferative, stage. Fragile, new blood vessels grow along the retina and in the clear, gel-like vitreous that fills the inside of the eye. Without timely treatment, these new blood vessels can bleed, cloud vision, and destroy the retina.
What Are the Different Types of Diabetic Retinopathy?
Non-proliferative Diabetic Retinopathy (NPDR)
Non-proliferative diabetic retinopathy, also known as background retinopathy, is the early stage of diabetic retinopathy. In this stage, tiny blood vessels in the peripheral retina leak blood and fluid.
People with non-proliferative diabetic retinopathy may experience no difficulties with vision. However, those who do experience problems are those who develop macular edema or macular ischemia.
- Macular edema occurs when the macula, the small area in the center of the retina that provides central detail vision, can swell from the leakage of blood and fluid from blood vessels in the retina. Central vision loss may be mild to severe, and side (peripheral) vision loss can also occur. Reduced sensitivity to color is also a result.
- Macular ischemia occurs when small blood vessels feeding the macula close off. Because the macula doesn't receive sufficient blood, the cells in the macula no longer work correctly, which causes vision to blur.
Proliferative Diabetic Retinopathy (PDR)
Proliferative diabetic retinopathy is the more severe stage of the disease when abnormal blood vessels grow into the retina or optic nerve. Because the disease can cause much of the circulation of the retina to close down, abnormal blood vessels grow into the retina to augment the reduced blood flow. Unfortunately, these abnormal vessels do not re-supply the reduced blood flow. These vessels are often fragile or accompanied by scar tissue, which may cause the retina to pull away from the wall of the eyeball -- causing retinal detachment or retina hemorrhage.
Because abnormal blood vessels can grow in any part of the retina, not just the macula, both central and peripheral vision is affected with proliferative diabetic retinopathy. PDR can cause one of the following complications leading to potential vision loss:
One of the complications of proliferative diabetic retinopathy is hemorrhage from fragile blood vessels leaking into the vitreous, the clear gel-like substance that fills the interior of the eye. If blood clouds the vitreous, light passing from the lens through the vitreous to the retina is blocked, and vision is markedly reduced. Blood can generally clear up over several months, but if it does not, surgical removal of the vitreous, called vitrectomy, can be performed. Specialists in vitreo-retinal surgery can remove blood and scar tissue from the eye and replace the vitreous with a clear solution. This may result in useful, though reduced, vision.
Secondary glaucoma is also known as neovascular glaucoma. With this complication, fragile new blood vessels in the eye may form a new network directly on the iris, blocking the outflow of fluid from the eye. This condition results in elevated pressure of the fluids within the eye, and can cause optic nerve atrophy and loss of the full visual field. Treatment involves the application of laser to the leaking areas. Standard glaucoma treatment with drops or diuretics may also be recommended to lower intraocular pressure. For more information on glaucoma click here (LINK).
The abnormal blood vessels that grow in proliferative diabetic retinopathy are often accompanied by hemorrhage and scar tissue formation. This scarring can cause wrinkling of the retina and even separation from the wall of the globe. This is known as retinal detachment. Wrinkling of the retina can result in visual distortion whereas retinal detachment can cause severe vision loss depending on where the separation has occurred.
Symptoms
With diabetes, you may notice no changes in your vision at first. However, uncontrolled diabetes can gradually get worse over the years and threaten your good vision.
Diabetic retinopathy often has no early warning signs. At some point, though, you may develop macular edema, which can blur vision, making it hard to do things like read and drive. In some cases, your vision will get better or worse during the day.
As new blood vessels form at the back of the eye, they can bleed (hemorrhage) and blur vision. The first time this happens it may not be very severe. In most cases, it will leave just a few specks of blood, or spots, floating in your vision. They often go away after a few hours.
However, gradually these spots are followed within a few days or weeks by a much greater leakage of blood. The blood will blur your vision.
In a vitreous hemorrhage, a person will only be able to tell light from dark in that eye. It may take the blood anywhere from a few days to months -- or even years -- to clear from the inside of your eye. In some cases, the blood will not clear spontaneously and must be surgically removed by vitrectomy.
Diagnosis
Diabetic retinopathy is detected during an eye examination that includes:
- Visual acuity test
This eye test, which measures how well you see at various distances, has two components. It measures accurate vision without correction as well as best corrected vision confirmed by refraction.
- Pupil dilation
The eye care professional places drops into the eye to widen the pupil. This allows the doctor to see more of the retina and look for signs of diabetic retinopathy. After the examination, close-up vision may remain blurred for several hours.
- Ophthalmoscopy
This is an examination of the retina in which the eye care professional: (1) looks through a special magnifying lens that provides a narrow view of the retina, or (2) wearing an indirect ophthalmoscope with a bright light, looks through a special magnifying glass to gain a wide view of the retina.
- Tonometry
A standard test that determines the fluid pressure inside the eye. Elevated pressure is a possible sign of secondary glaucoma, another common eye problem in people with diabetes.
Your eye care professional will look at your retina for early signs of diabetic retinopathy, such as: (1) leaking blood vessels, (2) retinal swelling -- signs of macular edema, (3) pale, fatty deposits on the retina -- signs of leaking blood vessels, (4) damaged nerve tissue, and (5) any changes in the blood vessels.
Should your doctor suspect that you need treatment for macular edema, he or she may ask you to have a test called fluorescein angiography.
In this test, a special dye is injected into your arm. Pictures are then taken as the dye passes through the blood vessels in the retina. This test allows your doctor to determine the location of the leaking blood vessels.
Risk Factors
All people with diabetes are at risk for diabetic retinopathy -- those with type I diabetes (juvenile onset) and those with type II diabetes (adult onset). Diabetic Retinopathy affects half of all Americans diagnosed with diabetes.
During pregnancy, diabetic retinopathy may also be a problem for women with diabetes. It is recommended that all pregnant women with diabetes have dilated eye examinations each trimester to protect their vision.
What You Can Do to Reduce Risk
The National Eye Institute urges all people with diabetes to have an eye examination through dilated pupils at least once a year, more often if you have more serious retinopathy.
A recent study, the Diabetes Control and Complications Trial (DCCT), showed that better control of blood sugar levels slows the onset and progression of retinopathy and lessens the need for laser surgery for severe retinopathy.
The study found that the group that tried to keep their blood sugar levels as close to normal as possible, had much less eye, kidney, and nerve disease. This level of blood sugar control may not be best for everyone, including some elderly patients, children under 13, or people with heart disease, so ask your doctor if this program is right for you.
Treatment
There are two treatments for diabetic retinopathy. They are very effective in reducing vision loss from this disease. In fact, even people with advanced retinopathy have a 90 percent chance of keeping their vision when they get treatment before the retina is severely damaged.
These two treatments are laser surgery and vitrectomy. It is important to note that although these treatments are very successful, they do not cure diabetic retinopathy.
Doctors will perform laser surgery to treat severe macular edema and proliferative retinopathy.
Timely laser surgery can reduce vision loss from macular edema by half, but you may need to have laser surgery more than once to control the leaking fluid.
During surgery, your doctor will aim a high-energy beam of light directly onto the damaged blood vessels. This is called focal laser treatment. This seals the vessels and stops them from leaking. Generally, laser surgery is used to stabilize vision, not necessarily to improve it.
In treating advanced diabetic retinopathy, doctors use the laser to destroy the abnormal blood vessels that form at the back of the eye.
Rather than focus the light on a single spot, your eye care professional will make hundreds of small laser burns away from the center of the retina. This is called scatter laser treatment. The treatment shrinks the abnormal blood vessels. You will lose some of your side vision after this surgery to save the rest of your sight. Laser surgery may also slightly reduce your color and night vision.
Once you have proliferative retinopathy, you will always be at risk for new bleeding. This means you may need treatment more than once to protect your sight.
Laser surgery is performed in a doctor's office or eye clinic. Before the surgery, your ophthalmologist will: (1) dilate your pupil and (2) apply drops to numb the eye. In some cases, the doctor also may numb the area behind the eye to prevent any discomfort.
The lights in the office will be dim. As you sit facing the laser machine, your doctor will hold a special lens over your eye. During the procedure, you may see flashes of light. These flashes may create a stinging sensation that makes you feel a little uncomfortable.
You may leave the office once the treatment is done, but you will need someone to drive you home. Because your pupils will remain dilated for a few hours, you also should bring a pair of sunglasses.
For the rest of the day, your vision will probably be a little blurry. If your eye hurts a bit, your eye care professional can suggest a way to control this. Also, your night vision may be decreased.
Instead of laser surgery, you may need an eye operation called a vitrectomy to restore your sight. A vitrectomy is performed if the retina bleeds into the vitreous. It involves removing the cloudy vitreous and replacing it with a normal saline solution. Because the vitreous is mostly water, you will notice no change between the salt solution and the normal vitreous.
Studies show that people who have a vitrectomy soon after a large hemorrhage are more likely to protect their vision than those who wait to have the operation.
Early vitrectomy is especially effective in people with insulin-dependent diabetes, who may be at greater risk of blindness from a hemorrhage into the vitreous.
Vitrectomy is often done under local anesthesia. This means that you will be awake during the operation. The doctor makes a tiny incision in the sclera, or white of the eye. Next, a small instrument is placed into the eye. It removes the vitreous and replaces it with a saline solution in the eye.
You may be able to return home soon after the vitrectomy. Or, you may be asked to stay in the hospital overnight. Your eye will be red and sensitive. After the operation, you will need to wear an eyepatch for a few days or weeks to protect the eye. You will also need to use eye drops to protect against infection and inflammation.
Source: National Eye Institute, National Institutes of Health |
