What is diabetic retinopathy?
Diabetic retinopathy (DR) is the most common type of diabetic eye disease and the leading cause of blindness in American adults. Diabetes causes damage to the blood vessels of the retina, a thin and delicate tissue that is responsible for vision. In some people suffering from DR, blood vessels swell and leak fluid. In others, abnormal new blood vessels grow on the surface of the retina that can lead to bleeding and retinal detachment. A healthy retina is necessary for good vision.
If you have diabetic retinopathy, at first you may not notice changes to your vision. Yet over time, the condition can worsen and cause vision loss. Diabetic retinopathy usually affects both eyes, but early detection and prompt treatment can minimize vision loss.
What are the four stages of diabetic retinopathy?
Mild Nonproliferative Retinopathy
The features of mild nonproliferative retinopathy are some of the earlier stages of diabetic retinopathy. At this point, small areas of balloon-like dilation of blood vessels, called microaneurysms, start to appear along with other findings such as small spot hemorrhages and cotton wool spots. It's important to note that not all patients with mild nonproliferative retinopathy will notice a change in their vision.
Moderate Nonproliferative Retinopathy
Moderate nonproliferative retinopathy is essentially a progression from the mild stage. Many more microaneurysms, hemorrhages and cotton wool spots emerge and there is further damage to the retinal blood vessels. The danger is that such damage can result in reduced blood flow to the surrounding retinal tissue leading to vision loss.
Severe Nonproliferative Retinopathy
As the retinopathy progresses and more blood vessels have now been affected, larger areas of the retina are deprived of blood flow. This results in the retina producing new blood vessels in an attempt to enhance nourishment.
At this advanced stage, the signals sent by the retina for nourishment trigger the growth of new blood vessels that grow along the retina and into other parts of the eye. These blood vessels are abnormal and fragile, often leading to the development of new or worsening existing symptoms and frequent vision loss. Left untreated, severe vision loss and even permanent blindness can result.
How does diabetic retinopathy cause vision loss?
Damaged blood vessels from diabetic retinopathy can cause vision loss in several ways:
- Fluid can leak into the macula, the center of the retina that is responsible for central vision. Just like a damaged garden hose, the damaged blood vessels surrounding the macula leak, and fluid accumulates around the surrounding macular tissue, causing it to swell and creating blurry vision. This is called diabetic macular edema and it can occur at any stage of diabetic retinopathy. It is the most common cause for reduced vision in diabetics.
- Abnormal new blood vessels can grow from the damaged retina. These fragile vessels tend to break and produce bleeding along the retina and vitreous cavity. This is called a vitreous hemorrhage and commonly causes floaters and, in severe cases, leads to vision loss.
Who is at risk for diabetic retinopathy?
All diabetics—both Types 1 & 2—are at risk, which is why everyone with diabetes should get a comprehensive dilated eye exam at least once a year. The longer someone has diabetes, the more likely he or she will develop diabetic retinopathy. It's fortunate that in most cases diabetic retinopathy is a treatable condition. Your doctor can recommend treatment to help prevent its progression.
Diabetic retinopathy may be a problem for women with diabetes during pregnancy. To protect vision, every pregnant woman with diabetes should have a comprehensive dilated eye exam as early as possible. Your doctor may recommend additional exams during your pregnancy.
What can I do to protect my vision?
Annual Dialated Eye Exams
Early detection and treatment can prevent vision loss. If you are diabetic, be sure to schedule a comprehensive dilated eye exam at least once a year. It is important to remember that your diabetic retinopathy can progress without symptoms. You can develop both proliferative retinopathy and macular edema and still see normally, but you may remain at high risk for vision loss. A retina specialist can tell if you have any stage of diabetic retinopathy or macular edema. Depending on the severity of your diabetic retinopathy, your doctor may suggest you have more frequent exams.
Blood Sugar Control
The results of large clinical trials have shown that better control of blood sugar levels slows the onset and progression of retinopathy. In general, diabetic patients who kept their blood sugar levels as close to normal as possible also had significantly less kidney and nerve disease. Better control also reduced the need for sight-saving laser surgery. This level of blood sugar control, however, may not be best for everyone. Patients should routinely see their primary care provider who can determine the best form of blood sugar control for you. Other studies have found that controlling elevated blood pressure and cholesterol can reduce the risk of vision loss. And certainly doing so will also help your overall health.
How will I know if I have diabetic retinopathy?
There are often no symptoms during the early stages of the disease, nor is there any pain. It's important, therefore, not to wait for symptoms. Be sure to have a comprehensive dilated eye exam at least once a year. When symptoms do occur, they range from mildly blurred central vision to complete vision loss. Symptoms may progress slowly—or rapidly. It is critical to secure prompt medical attention if you notice any change in your vision.
Symptoms of Advanced Disease
Proliferative retinopathy frequently produces symptoms as a result of bleeding into the vitreous cavity. At first, you may notice a few specks of blood "floating" in your vision. If that occurs, see your retina specialist as soon as possible; you may need treatment before more serious bleeding occurs. Hemorrhages tend to happen more than once, often during sleep. Sometimes, even without treatment, the spots clear, and your vision will improve. Yet it's more likely that bleeding will reoccur and cause severely blurred vision. You need to be examined by your retina specialist at the first sign of blurred vision, before more bleeding occurs. The earlier you receive treatment, the more likely treatment will be effective. If left untreated, proliferative retinopathy can cause severe vision loss and even blindness.
How is diabetic retinopathy diagnosed?
Diabetic retinopathy is detected during a comprehensive eye exam. After checking your vision and eye pressure, drops are placed in your eyes to widen, or dilate, the pupils. A retina specialist uses a special magnifying lens to examine your retina for signs of diabetic retinopathy.
Your retina specialist may also order special testing to help stage the retinopathy or decide if treatment is needed. One test, a fluorescein angiogram, uses a special dye that is injected into your arm. Pictures are taken as the dye passes through the blood vessels in your retina, allowing for the identification of any leaking blood vessels that may require treatment. Your doctor may also recommend Ocular Coherence Tomography, or OCT, to check for diabetic macular edema. This is a non-invasive test, similar to an ultrasound, that helps detect fluid within the macula. After the exam, your close-up vision may remain blurred for several hours due to the dilating drops.
How is non-proliferative diabetic retinopathy treated?
During the stages of mild and moderate non-proliferative diabetic retinopathy, no treatment is needed unless macula edema is present. To prevent the progression of diabetic retinopathy, people with diabetes should control their blood sugar, blood pressure and cholesterol.
How is a diabetic macular edema treated?
Focal Laser Treatment (Focal Photocoagulation)
Macular edema is most effectively treated with focal laser treatment that is usually completed in one session. Your doctor seals leaking blood vessels (microaneurysms) with light heat generated by a laser. These treatment spots slow the leakage of fluid and reduce the amount of fluid in the macula. Focal laser treatment slows the rate of vision loss by about 50 percent and can improve visual acuity. You may need focal laser more than once to control the leaking fluid. If you have macular edema in both eyes and require laser treatment, most often only one eye is treated at a time.
Grid Laser Treatment/Grid Photo Coagulation
For more wide-spread macular swelling (edema), grid laser is often used. Other treatments can be coupled with grid laser to try and preserve vision.
What happens during laser treatment?
Both focal and grid laser treatments are performed in your doctor's office with the lights dimmed. Before the treatment, your physician will dilate your pupil and apply drops to numb the eye. As you sit facing the laser machine, your doctor will hold a special lens to your eye. During the procedure, you will see flashes of bright light. Although the flashing lights are often described as annoying, there is generally little to no discomfort associated with this procedure.
Laser treatment will at best stabilize vision, but generally cannot restore vision that has been lost. This is yet another reason that treating diabetic retinopathy early is the best way to prevent vision loss.
It is highly uncommon to experience a decline in vision following treatment, and with the majority of patients who do, it is a temporary condition. You should call your retina specialist immediately if any abnormal symptoms develop.
Certain drugs have been used to successfully reduce macular edema and new blood growth resulting from diabetic retinopathy. The agents used, steroids and anti-vascular endothelial growth factor drugs (VEGF), are injected into the eye to reduce leakage, swelling or new blood vessel growth. Unfortunately, the benefit of these drugs is often temporary, and they need to be injected multiple times to sustain their effects. The eye is numbed before each injection and the doctor closely monitors each patient's condition following the injection. In some instances, these injections can be used in combination with laser treatment. The Retina Group of Washington is involved in multiple national clinical trials evaluating the benefits of different medications in treating diabetic retinopathy.
A small number of patients may be helped by vitrectomy surgery for macular edema. Your doctor will tell you whether you are a candidate for such a treatment.
How is proliferative diabetic retinopathy treated?
There are two major therapies for proliferative diabetic retinopathy—scatter laser treatment and vitrectomy.
Scatter Laser Treatment (Panretinal Photocoagulation)
Scatter laser treatment helps to shrink the abnormal blood vessels. Your doctor places laser spots throughout the entire peripheral retina, causing the abnormal blood vessels to shrink. Because it's necessary to use a large number of laser spots, more than one session is often required to complete treatment. Although you may notice some loss of side vision—and it may slightly reduce your color and night vision—scatter laser treatment is needed to preserve your central vision. This treatment is more effective before the fragile, new blood vessels have started to bleed which is why it is important to have regular, comprehensive dilated eye exams. Even if bleeding has begun, scatter laser treatment may still be possible, based on the amount of bleeding.
In some instances, anti-VEGF drugs may be used in conjunction with laser to treat severe forms of proliferative diabetic retinopathy.
Some degree of discomfort is common with this treatment. It usually subsides at the end of the procedure, but some patients report mild discomfort or a mild headache lasting for the rest of the day. Other complications are rare, but will be explained prior to your procedure.
You may require a surgical procedure called a vitrectomy if bleeding is severe, if it does not clear up on its own or if you develop a retinal detachment related to your diabetic retinopathy. This procedure is almost always performed on an out-patient basis under local anesthesia. Your doctor inserts tiny instruments through small incisions in the sclera (the white portion of the eye) and removes the gel and blood from the center of the eyeball. He or she will then replace the clouded gel with a clear saline solution or gas bubble. Following the procedure, an eye patch is placed on the operated eye and you need to return to the office the next day.
Prior to surgery, your doctor will explain the rare but possible complications of vitrectomy surgery.
Are scatter laser treatment and vitrectomy effective in treating proliferative retinopathy?
Both are very effective in reducing vision loss. Although they both have high success rates, neither one cures diabetic retinopathy, but rather reduces the risk of new bleeding. Vitrectomy surgery can—and usually does—improve vision, but scatter laser is employed to stabilize vision. You may need multiple treatments to protect your sight.
What can I do if I already have lost some vision from diabetic retinopathy?
Ask your retina specialist about referring you to a low vision specialist and about low vision services and devices that may help you make the most of your remaining vision. Closed circuit television with electronic magnification and image intensification is a commonly-used aide as are lens magnifiers combined with a brighter light. Patients are often given the opportunity to test low vision products at home before purchasing them.