As a primary eye care practitioner, I am continually astonished by the number of diabetes patients I see who have either never had a dilated eye exam or feel they don’t require one (or at least not as often as I recommend). Then there are people with diabetes who are shocked to find out that their eye or vision problems are related to their diabetes. As an eye doctor, I am very aware of the link between diabetes and the potential for eye problems including blindness. One of our jobs as an eye care provider is to talk to our diabetes patients about the associated ocular health risks and dangers they may face as a result of their condition. One eye disease all people with diabetes should be aware of is diabetic retinopathy. If you are already aware of this disease, then I am offering a reminder of how important it is for your to understand the symptoms, treatments and what you can do to avoid this diabetes-related vision complication.
It is at this point I recall the alarming statistics that come across my desk on a weekly basis. One of the most disturbing statistics to me is that diabetes is the primary cause of blindness in Americans 75 years of age or younger and the primary cause of new cases of blindness, most commonly from diabetic retinopathy.
Diabetic retinopathy is when diabetes affects the retina, the inner light-sensitive tissue lining the back of the eye. This is called diabetic retinopathy. We like to think of the retina as the film in a camera. If it is damaged then the picture is never developed or seen – that is why retinopathy is the main threat to vision.
There are four stages of diabetic retinopathy:
- Mild nonproliferative retinopathy: This is the earliest phase which can begin after diabetes has affected the circulatory system of the retina. The walls of the retinal capillaries become weakened and microaneurysms form, which are small balloon-like outpouches of the petite blood vessels. Microaneurysms can leak blood, forming small dot-like hemorrhages, as well as fluid leading to swelling or edema in the retina.
- Moderate non-proliferative retinopathy: In this stage, the disease progresses or worsens, and there is blockage of the nourishing blood vessels of the retina.
- Severe non-proliferative retinopathy: As more blood vessels are blocked, the retina becomes deprived of oxygen or what we call “ischemic.” In order to uphold adequate oxygen supply, the retina sends a signal to the body to grow new fragile blood vessels in an attempt to bring in nourishment.
- Proliferative retinopathy: Once these new blood vessels are formed, this is known as neovascularization and the condition has converted to proliferative retinopathy. Proliferate indicates growth or flourishing of the new blood vessels not only along the retinal surface, but also growth into the vitreous gel which fills the inside of the eye. Since these vessels are fragile and delicate they leak and bleed (hemorrhage) causing obscured vision, blind spots, and if left untreated, blindness from retinal detachment.
These stages are important to understand. However, it is just as or even more important to understand there is the possibility of macular edema, which is usually the primary cause of vision loss in diabetics. The macula is a very important part of our visual system and is where straight-ahead, detailed vision occurs. When fluid leaks into the center of the macula from damaged blood vessels, as described above, the macula swells and is what we term macular edema. Macular edema can happen at any stage of diabetic retinopathy, but it can more likely occur as the disease advances, so much so that roughly half of diabetics with proliferative retinopathy (Stage 4) also have macular edema.
Symptoms of retinopathy vary, but what is most concerning is that often there are no symptoms, especially in the early stages. You can develop both macular edema and proliferative retinopathy and still see fine. The best way to prevent vision loss is early detection and timely treatment. Everyone with diabetes, type 1 or 2, is at risk and should have a comprehensive dilated eye exam at least once a year. If retinopathy is present, an eye exam may be needed more often and treatment may be recommended to prevent progression. Also, women with diabetes who become pregnant should have an eye exam within the first trimester, and should be watched closely thereafter, even into the first year postpartum. This does not apply to women who develop gestational diabetes as they have no increased risk for developing retinopathy.
The likelihood of developing diabetic retinopathy goes up the longer you have diabetes, but 40-45% of Americans diagnosed with diabetes have some stage of retinopathy. The best thing someone with diabetes can do to slow the onset and progression of retinopathy is to control their blood sugar, as shown by the Diabetes Control and Complications Trial. In addition, controlling elevated blood pressure and cholesterol in addition can reduce the risk of vision loss, as hypertension is a major risk factor for developing macular edema. That is why I ask all of my diabetic patients what their last blood sugar reading was, as well as their Hemoglobin A1C, their blood pressure and cholesterol levels.
Treatment for diabetic retinopathy depends on the stage and specific problem. Often your eye care professional will rely on special tests, fluorescein agiography, macular OCT imaging and even retinal photography to monitor progression and make decisions on appropriate treatment. More often than not, you will be referred to a retinal specialist to assess the need and type of treatment. Proliferative retinopathy is treated with a scattered laser treatment over a wide area called PRP (panretinal photocoagulation). Macular edema is treated with focal laser treatment to the area surrounding the macula. Both are effective and have high success rates in reducing vision loss, but they do not cure diabetic retinopathy. You will always be at risk for new bleeds. At times bleeding can be severe and requires a surgical procedure called a vitrectomy to remove the blood from floating in the center of the eye. Other possible treatments may be needed if the initial ones aren’t effective, or further complications such as retinal detachment arise.
As you can see, diabetes can take a toll on your eyes and I cannot stress enough the importance of being proactive and maintaining proper blood sugar levels. If you are one of the more than 18 million American children and adults affected by diabetes, I recommend you schedule regular eye exams to reduce the possibility of ocular complications. The earlier a problem is caught, the greater the success of treatment.