There are approximately 16 million Americans who have diabetes. All are at risk of developing sight-threatening eye diseases that are common complications of diabetes. Karen Gehrs, MD, ophthalmologist at University of Iowa Hospitals and Clinics, talks about diabetic eye disease:
What is diabetic eye disease?
Diabetic eye disease refers to the problems that can develop in the eye as a result of circulation damage caused by diabetes. It can affect all parts of the eye, but the retina is the part that is affected most and what most people think of when we refer to diabetic eye disease.
What is the most common diabetic eye disease?
Diabetic retinopathy refers to the changes that we see in the retina and it goes through stages. Initially there are just some minor small hemorrhages, small spots of cholesterol development, blood vessels that are a little more tortuous than normal, and that’s called background or non-proliferative retinopathy, and most people who have that aren’t even aware that it’s there. Then as the circulation becomes worse, two things can occur. One is that the circulation in the center part of vision, the macula, is not as good as it should be and the tissue starts to swell and that’s diabetic macular edema. And initially it may have no symptoms, but later people may notice blurry or wavy vision. The other problem that can develop is new blood vessels can sprout in response to poor circulation. That’s called proliferative retinopathy and the blood vessels are not healthy, good blood vessels so they can hemorrhage and lead to things -- to more problems down the road, like hemorrhaging in the eye and a detached retina.
How does diabetic retinopathy cause vision loss?
The swelling in the center, the diabetic macular edema, actually causes the part of the eye that’s collecting the light and the images to be swollen and so it’s a bit bumpy and it would be similar to projecting a picture on a movie screen that had bumps in it. You wouldn’t get a smooth picture because the screen you were projecting on is not smooth. And proliferative retinopathy can affect vision in two ways. One, as the blood vessels grow, they can hemorrhage and that causes people to see a lot of floaters. It may cause them to see sort of filmy or foggy vision because they’re actually looking through blood. Over time that bleeding can lead to the development of scar tissue. The scar tissue can contract or pucker and when it does that it pulls on the retina and can actually detach the retina, and that can lead to very severe vision loss because the tissue is actually being lifted up from its normal location and then it doesn’t see very well.
Who is at risk to develop diabetic retinopathy?
Everyone who has diabetes is at risk. The risk is lower the better the diabetes control. Or conversely, the higher, the worse the diabetes control. So, everyone with diabetes is at risk for retinopathy and you can lower that risk by optimal diabetes control as well as good blood pressure and cholesterol management.
What are the symptoms of diabetic retinopathy?
Most people, particularly in the early stages, have no symptoms at all and that’s why it’s important that they have regular eye exams to detect it at an early stage. Once someone starts having symptoms, typically they might see floaters, little black specks. Floaters are quite common. Everybody probably has floaters from time to time. Floaters essentially are the shadow cast by opacities in the vitreous gel and as we all get older, our vitreous gel becomes more watery and gets clumps of protein in it. And so everybody has some floaters, but typically with diabetes, people will often notice a lot of black specks, which is blood, or a big blob which could be a larger area of blood. Sometimes patients will describe a thin line that then spreads out into a big blob. That would be the symptoms of a hemorrhage. And sometimes the hemorrhage is so severe that the person can only see light out through the blood. The wavy vision or wrinkling of vision can happen if there’s swelling or if there’s scar tissue that’s wrinkling the retina.
How is diabetic eye disease detected?
It’s important that everyone with diabetes has an eye exam at least once a year, and that way their eye doctor can determine what stage they’re at and then if they have no retinopathy, we tell them to come back yearly. If they have very mild retinopathy and good control, typically we tell them also to come back yearly. If it’s more advanced and/or the person’s diabetes control is not very good, then the eye doctor will tell them to come back more frequently and how frequently really depends on what we see. There are now camera systems that have been developed to detect retinopathy and there are programs all over the country, including one at The University of Iowa, to try to have people have an eye photo when they’re going for some other appointment, say to their internist or their endocrinologist.
The cameras don’t look at the entire retina, but they focus on the part that’s most likely to be affected, and then if we see anything on the photos, then the patients are recommended to have a complete eye exam. So someone with ideal control who has no retinopathy with a complete eye exam, photo screening may be a good option for them periodically with eye exams in between to supplement it as needed. The photos do not detect any other eye problems, though, so if someone were to have other problems, like glaucoma, macular degeneration, or something, the photos would not necessarily detect those things. There are a lot of different cameras and it’s important to make sure that the photos are being taken with one that has the resolution to detect the disease. Just because you have a photo taken doesn’t necessarily mean it was a good photo, so people who are doing that need to investigate to make sure they’re good photos. Those are basically the two ways to detect it and then how often to be evaluated depends on what’s seen at the first evaluation.
How is diabetic retinopathy treated?
The first thing we always do is make sure to communicate with the patient’s primary care physician or endocrine doctor to make sure their diabetes is under ideal control because all of the treatments work better if the diabetes is under good control. If someone has poor control, they still may get some benefit from the treatment but not as much, so the first step is to make sure they’re well controlled. And then, depending on what the person has, if they have no swelling and no new blood vessels, they’re just observed. If they actually have swelling then typically some testing is done to determine the source of the leakage and how much leakage is there.
Often a test called fluorescein angiogram, where some dye is injected to look at the actual areas that are leaking, so that the next step – laser treatment ?] can be applied. There’s also some newer technology that can actually measure how swollen the tissue is and it’s called ocular coherence tomography. And we use that to judge how people respond to treatment. As far as the proliferative disease, the new blood vessels, that’s also treated with laser treatment, the gold standard for treatment of diabetic retinopathy. In recent years there have also been some medications that are being studied that can be potentially injected into the eyes, often to assist or augment the laser, but laser is still the mainstay of therapy. The medications that are injected don’t last forever and they often are used to sort of help delays, or work better, or to sort of maybe get someone’s eyes, to get the problems turned around while they’re getting their diabetes under good control. But ultimately laser treatment and good control are the real foundation for treatment.
If someone has lost some vision due to diabetic retinopathy, is it possible to still be treated?
It’s still possible to be treated, it’s just that the treatments don’t tend, in most cases, to bring much vision back. If it’s just that you’re drying up leakage or you’re drying up blood vessels, if someone has had enough bleeding that the laser is not sufficient anymore and they have to go on to the next step, which is called the vitrectomy surgery, where we actually remove the blood and the scar tissue and the blood vessels from the eye, vision may improve just because you removed the blood. And vision can improve with laser, it’s just laser is more to preserve what vision people have and to keep things from getting worse. So patients who are having lasers shouldn’t be discouraged that they’re not getting dramatically better, because the vision problem is really a result of poor circulation and thus far there’s no therapy that can bring back circulation that’s already gone.
Is University of Iowa Hospitals and Clinics involved in any research with regard to diabetic eye disease?
We have the screening program that I mentioned that’s looking at better and better ways to detect retinopathy early, because since we know most treatments prevent vision loss, we’d like to get to people as early as we can. So that’s the first thing is looking at better methods for reaching people. Because often most people who have diabetic retinopathy, a lot of people who have diabetes don’t even know they have it, and people with retinopathy often don’t know they have it. So number one is research to try to improve detection at an early stage. And then we’ve participated in a number of trials over the year, some of which are ongoing.
Systemic medications in the form of pills or long-acting injections (intramuscular injections) that might help slow down retinopathy and help treat diabetes better, a number of those are still in the process. And then, ultimately, there are always studies looking at different lasers and that. There’s not a particular story that we’re recruiting for right now because the studies we’re involved in are mostly recruited at this point, but people can always check our Web site for the Department of Ophthalmology and that lists trials that may be coming up in the future when we’re looking for patients to participate in trials. |
Karen Gehrs, MD
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