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Diabetic Retinopathy – Eye Pathology/Treatment
The four stages of diabetic retinopathy
Diabetic Retinopathy
Diabetic eye disease refers to a group of eye problems that people with diabetes may face as a complication of diabetes. All can cause severe vision loss or even blindness.
Diabetic eye disease may include:
* Diabetic retinopathy—damage to the blood vessels in the retina.
* Cataract—clouding of the eye’s lens. Cataracts develop at an earlier age in people with diabetes.
* Glaucoma—increase in fluid pressure inside the eye that leads to optic nerve damage and loss of vision. A person with diabetes is nearly twice as likely to get glaucoma as other adults.
Diabetic retinopathy is the most common diabetic eye disease and a leading cause of blindness in American adults. It is caused by changes in the blood vessels of the retina.
In some people with diabetic retinopathy, blood vessels may swell and leak fluid. In other people, abnormal new blood vessels grow on the surface of the retina. The retina is the light-sensitive tissue at the back of the eye. A healthy retina is necessary for good vision.
If you have diabetic retinopathy, at first you may not notice changes to your vision. But over time, diabetic retinopathy can get worse and cause vision loss. Diabetic retinopathy usually affects both eyes. The four stages of diabetic retinopathy
1. Mild Nonproliferative Retinopathy. At this earliest stage, microaneurysms occur. They are small areas of balloon-like swelling in the retina’s tiny blood vessels.
2. Moderate Nonproliferative Retinopathy. As the disease progresses, some blood vessels that nourish the retina are blocked.
3. Severe Nonproliferative Retinopathy. Many more blood vessels are blocked, depriving several areas of the retina with their blood supply. These areas of the retina send signals to the body to grow new blood vessels for nourishment.
4. Proliferative Retinopathy. At this advanced stage, the signals sent by the retina for nourishment trigger the growth of new blood vessels. This condition is called proliferative retinopathy. These new blood vessels are abnormal and fragile. They grow along the retina and along the surface of the clear, vitreous gel that fills the inside of the eye. By themselves, these blood vessels do not cause symptoms or vision loss. However, they have thin, fragile walls. If they leak blood, severe vision loss and even blindness can result.
Causes and Risk Factors
Blood vessels damaged from diabetic retinopathy can cause vision loss in two ways:
1. Fragile, abnormal blood vessels can develop and leak blood into the center of the eye, blurring vision. This is proliferative retinopathy and is the fourth and most advanced stage of the disease.
2. Fluid can leak into the center of the macula, the part of the eye where sharp, straight-ahead vision occurs. The fluid makes the macula swell, blurring vision. This condition is called macular edema. It can occur at any stage of diabetic retinopathy, although it is more likely to occur as the disease progresses. About half of the people with proliferative retinopathy also have macular edema.
All people with diabetes — both type 1 and type 2 — are at risk. That’s 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 get diabetic retinopathy. Between 40 to 45 percent of Americans diagnosed with diabetes have some stage of diabetic retinopathy. If you have diabetic retinopathy, your doctor can recommend treatment to help prevent its progression.
During pregnancy, diabetic retinopathy may be a problem for women with diabetes. To protect vision, every pregnant woman with diabetes should have a comprehensive dilated eye exam as soon as possible. Your doctor may recommend additional exams during your pregnancy. Protecting vision
It is important to have a comprehensive dilated eye exam at least once a year.
* Proliferative retinopathy can develop without symptoms. At this advanced stage, there is a high risk for vision loss.
* Macular edema can develop without symptoms at any of the four stages of diabetic retinopathy.
* Both proliferative retinopathy and macular edema may develop.
People with proliferative retinopathy can reduce their risk of blindness by 95 percent with timely treatment and appropriate follow-up care.
The Diabetes Control and Complications Trial (DCCT) showed that better control of blood sugar levels slows the onset and progression of retinopathy. The people with diabetes who kept their blood sugar levels as close to normal as possible also had much less kidney and nerve disease. Better control also reduces the need for sight-saving laser surgery.
This level of blood sugar control may not be best for everyone, including some elderly patients, children under age 13, or people with heart disease. Other studies have shown that controlling elevated blood pressure and cholesterol can reduce the risk of vision loss. Controlling these will help overall health as well as help protect vision. Symptoms
Often there are no symptoms in the early stages of the disease, nor is there any pain. Blurred vision may occur when the macula—the part of the retina that provides sharp central vision—swells from leaking fluid. This condition is called macular edema.
If new blood vessels grow on the surface of the retina, they can bleed into the eye and block vision.
At first, a few specks of blood, or spots are noted, “floating” in vision. Hemorrhages tend to happen more than once, often during sleep.
Sometimes, without treatment, the spots clear, and vision improves. However, bleeding can recur and cause severely blurred vision. If left untreated, proliferative retinopathy can cause severe vision loss and even blindness. Also, the earlier treatment is received, the more effective it is. Detection
Diabetic retinopathy and macular edema are detected during a comprehensive eye exam that includes:
1. Visual acuity test. This eye chart test measures vision at various distances.
2. Dilated eye exam. Drops are placed in the eyes to widen, or dilate, the pupils. This allows the eye care professional to see more of the inside of the eye to check for signs of the disease. A special magnifying lens is used to examine the retina and optic nerve for signs of damage and other eye problems. After the exam, close-up vision may remain blurred for several hours.
3. Tonometry. An instrument measures the pressure inside the eye. Numbing drops may be applied to the prior to this test.
If the ophthalmologist believes treatment is required for macular edema, a fluorescein angiogram may be suggested. In this test, a radiopaque dye is injected into the arm. Radiographs are taken as the dye passes through the blood vessels into the retina. Treatment
During the first three stages of diabetic retinopathy, no treatment is needed, unless macular edema is present. To prevent progression of diabetic retinopathy, people with diabetes should control their levels of blood sugar, blood pressure, and blood cholesterol.
Proliferative retinopathy is treated with laser surgery. This procedure is called scatter laser treatment. Scatter laser treatment helps to shrink the abnormal blood vessels. The doctor places 1,000 to 2,000 laser burns in the areas of the retina away from the macula, causing the abnormal blood vessels to shrink. Because a high number of laser burns are necessary, two or more sessions usually are required to complete treatment. Although some loss of side vision may occur, scatter laser treatment can save the rest of one’s sight. Scatter laser treatment may slightly reduce color vision and night vision.
Scatter laser treatment works better before the fragile, new blood vessels have started to bleed. That is why it is important to have regular, comprehensive dilated eye exams. Even if bleeding has started, scatter laser treatment may still be possible, depending on the amount of bleeding.
If the bleeding is severe, a surgical procedure called a vitrectomy is done. During a vitrectomy, blood is removed from the center of the eye.
Macular edema is treated with laser surgery. This procedure is called focal laser treatment. Several hundred small laser burns in the areas of retinal leakage surrounding the macula are performed. These burns slow the leakage of fluid and reduce the amount of fluid in the retina. The surgery is usually completed in one session.
A patient may need focal laser surgery more than once to control the leaking fluid. If the macular edema is present in both eyes, generally only one eye will be treated at a time, usually several weeks apart.
Focal laser treatment stabilizes vision. In fact, focal laser treatment reduces the risk of vision loss by 50 percent. In a small number of cases, if vision is lost, it can be improved.
Both focal and scatter laser treatment are performed in a doctor’s office or eye clinic. Before the surgery, the pupils are dilated and numbing drops applied to the eye. A special lens is used to visualize the eye. During the procedure, the patient may see flashes of light.
Laser surgery and appropriate follow-up care can reduce the risk of blindness by 90 percent. However, laser surgery often cannot restore vision that has already been lost. That is why finding diabetic retinopathy early is the best way to prevent vision loss. Vitrectomy
If there is a lot of blood in the center of the eye (vitreous gel), a vitrectomy is used. A vitrectomy is performed under either local or general anesthesia. A tiny incision is made in the eye and a small instrument used to remove the gel that is clouded with blood. The gel is replaced with a salt solution. The postoperative eye is red and sensitive. A patch is used for days or weeks and eye drops employed to prevent infection. Laser treatment and vitrectomy for proliferative retinopathy
Yes. Both treatments are very effective in reducing vision loss. People with proliferative retinopathy have less than a five percent chance of becoming blind within five years when they get timely and appropriate treatment. Although both treatments have high success rates, they do not cure diabetic retinopathy. Loss of vision options
Devices are available to make the most of remaining vision. Low vision specialists provide counseling and training. SURGICAL COMPENDIUM…
For those who are interested, samples of eye surgery (dictation/reports) are available in our Surgical Compendium eBook
