Diabetic Retinopathy: The Often Overlooked Complication of Diabetes

Diabetic retinopathy is a disease that affects nearly 8 million Americans and is a leading cause of blindness in adults. In the latest episode of HealthSource Radio, Dr. Christopher Brady talks about the disease. Brady is an ophthalmologist at the UVM Medical Center and assistant professor at the Larner College of Medicine at UVM.

Listen to the interview at the link below, or read the transcript that follows.

Learn more about Ophthalmology (Eye Care) at the University of Vermont Medical Center. 

First things first: What is a retina?

Dr. Brady: The retina is the light-sensing tissue that lines the inside wall of our eye. It collects the light information, and sends it back to our brain. It captures the images and projects them. I call it the film of the eye like the film of a camera.

How many little pieces and parts are in there?

Dr. Brady: It’s a very complex little structure. It’s got multiple layers of nerve tissue. There are blood vessels that carry the blood nutrients and oxygen to the retina. Then, veins that carry that blood back to the heart.

Really it’s brain tissue that lives outside the brain. It’s very delicate. That’s part of the reason why damage to the retina can be devastating and sometimes can be permanent.

Why is it more likely to be permanent or why is at risk for being permanent?

Dr. Brady: Just because it’s very, very delicate tissue and I also say it’s a real estate issue. There’s a central part of the retina that we call the macula that is responsible for the most high definition or high resolution vision. If that little part of the retina is damaged, it really can’t repair itself.

Diabetes: Give people a general sense of what’s going on there and its impact on the body.

Dr. Brady: The basic issue with diabetes is the body has trouble dealing with sugar. Excess sugar in the bloodstream damages the body and in particular it damages blood vessels. As you mentioned, it damages blood vessels throughout the body. In the retina, we can see those blood vessels directly. When blood vessels are damaged, they can leak, they can bleed and they can also sprout new blood vessels and each of those things can cause vision loss.

When you’re talking about leaking, will people see blood in their vision?

Dr. Brady: Absolutely. Specifically if there is a little bit of leaking, people may not see specks of fluid per se. What they’ll often see is a general blurring or a distortion in their vision and that’s because I think of the retina like the film of a camera. If that film gets swollen, it can create a “funhouse” type of mirror effect where the image becomes distorted.

It can be mild, moderate or severe distortion. People can lose a substantial amount of vision. The other thing that can happen is if blood vessels burst, that can create blood inside the eyeball itself and that can cause more of a blockage of the vision where people are really seeing blood cells in their vision. It may look like floaters. It may look like thread or cobwebs, et cetera.

What is the first thing people would notice if they have retinopathy?

Dr. Brady: Well, I’d actually back up and say that people can have fairly significant damage with no symptoms whatsoever. That’s why probably the most important thing for people to know is that with diabetes, you need to get your eyes checked whether or not you’ve got any symptoms because we all see plenty of people who’ve got a fair amount of damage with no symptoms, 20/20 vision. Now, that being said, the first thing that people may notice is blurring of the vision, distortion, loss of vision or certainly floaters or cobwebs in their vision.  Those can all be signs of diabetic damage.

How quick is the progression of this?

Dr. Brady: It can really be going on for years. That’s why we know that if an adult is diagnosed with what we call Type 2 Diabetes, the recommendation is they get an exam really as soon as it’s practical and that’s because their body has really been having that difficulty dealing with sugar for some time even if their doctor hasn’t made the diagnosis of diabetes just yet. Although it can take years for this damage to occur, we generally think that there’s been a dysfunction probably for years at the time the diagnosis is made.

Diabetic Retinopathy: Is it irreversible?

Dr. Brady: The short answer is it’s reversible in many instances and that’s really I would say one of the great revolutions of my field over the last few decades. We’ve now taken a disease that was really universally untreatable and we are much better able to deal with it and reverse those changes now.

What else would start to happen?

Dr. Brady: Well, certainly people may just be noticing a decrease in vision because they may be experiencing some swelling in the retina and that swelling in the retina can cause really just a degradation of the image of the outside world that that retina is sensing and sending back to your brain. There are other structures within the eye that are also affected by diabetes, such as the lens of the eye, and that is something where people may notice vision that can fluctuate with their blood sugar levels. That’s a really classic sign of diabetes in the eye.

So if you have diabetes and you have any sign of trouble, I would think you should make a beeline for your doctor.

Dr. Brady: That would be my strong recommendation. It may not be that there is profound damage and you’re going to need to get with a retina specialist and get routine treatment. It may just be a little tune up of the glasses or something like that. But definitely we want to know what’s going on back there because, as you just mentioned, the symptoms may not match the severity of the damage in the eye.

What is an exam like?

Dr. Brady: Well, a normal diabetic exam will involve a comprehensive total eye exam. We’ll check your eye pressure. We’ll dilate the pupils which involves putting some drops in the eyes. Those drops are going to make things probably a bit blurry for you, and make you a bit more sensitive to the light for a few hours, but that’s important to help us see those structures behind the pupil of the eye and the retina so we can really see what’s going on back there.

There are new technologies on the horizon. One of the things I’m particularly interested in is the use of a technology to help us out with diabetic eye screenings. In the United Kingdom for example, the main way for screening for diabetes is actually done through retinal photography. You can get a photograph taken of the eye and then have a remote specialist review that image and make a determination of whether you have some diabetic damage.

What do the treatment options look like?

Dr. Brady: Diabetic retinopathy was really one of the early success stories in what I would call modern epidemiology of eye disease, by which I mean we used randomized control trials to figure out how to treat diabetic retinopathy. Now, randomized control trials are how every new medicine gets approved by the Food and Drug Administration. Ophthalmology was right at the forefront. In the ’70s and ’80s, we proved that the use of laser treatment could help prevent vision loss from diabetic retinopathy. More recently over the past decade, we have now shown that placing the medication directly into the eye is more effective in many instances than the laser itself.

Talk about the laser. What’s that all about?

Dr. Brady: Yes. The way that laser works is essentially using light energy and placing that inside the eye. The basic principle is that diabetes damages the blood vessels in the eye. When they’re damaged, that can lead to cell damage in the eye and cell death in the eye. When the cells are damaged and start to die, they start to release chemical signals that cause all the other changes of diabetic retinopathy.

You could think of it as either a stroke of genius or barbaric, but the idea is to take these cells that are damaged and dying and essentially just finish the job because it turns out that like many other things in the human body, it’s the human body’s response that is causing some of the damage. If we take the cells that are on their way out the door and just finish the job, we can turn off those signals that are causing that eye damage, the retinal damage, and that will cause an improvement in the vision and help the diabetic retinopathy improve.

We use the laser in a couple different ways and we do hope that when we’re performing this treatment that it can be more or less permanent.  If we can treat an appropriate area, we hope that that would be permanent. Now, I will say I think ophthalmology and part of what attracted me to the retina subspecialty within ophthalmology is the use of scientific data. And I think now that injection of medication directly into the eye has come into the forefront, we’re now learning that as much as we thought that laser treatment might be permanent, we now know that some people will need to be retreated and that’s information that came out of the study of these injections.

What are you injecting into the eye? Is that having the same effect, turning off the signals?

Dr. Brady: Yeah, absolutely. The basic point of those medications is to more or less soak up those chemical signals. We have several different medications that are in the same class and they will really chemically soak up those chemical signals. We also will sometimes inject a steroid medication which has a more broad effect inside the eye, but ultimately achieve the same goal of helping stabilize those blood vessels.

In broad strokes, it really does the same type of thing as the laser. We do worry a bit more about the permanence of the injections as compared with the laser and that’s why most of our patients are coming back for monthly injections at least at the very outset of their treatment.

We know those medications are gone from the eye within a couple of days. But they have achieved their goal of soaking up those chemical signals that are causing the swelling and other damage. But the body is going to produce more of those signals so we have to keep up with it. I explain to patients, just like they’ve got to keep up with maybe their pills for diabetes or their insulin treatment for diabetes, this isn’t a cure. Our treatment for diabetic retinopathy is more like our treatment for diabetes than it is for something like a pneumonia or a bronchitis or something like that where you might take antibiotics for a week or so and then be better.

What’s coming along that you find to be promising in terms of bettering treatment for this condition?

Dr. Brady: One of the questions people ask once I start talking with them is: “Is this something I have to do for my entire life?”

What I say is: “Look, if the progress of medicine stopped, and we got no new treatments, then, yes, I think it might be the case.” We know from studies that most people won’t need monthly treatment forever. We know that when we start treatment, it is much more intensive, then it tapers off over time.

In addition to that, people are working hard to come up with new treatments. Just like everything else in medicine, some of this stuff that seems really promising in the test tube or on paper doesn’t always pan out in human beings. We’ve got to take that as it comes. But certainly people are working on taking the medication that comprises these injections and coming up with ways to make it last longer in the eye so maybe we don’t have to do it as frequently.  They’re also coming up with combinations of medications, and whole new classes of medications. I think the future is really bright in this area. I think we’re already at a point where we’ve got much better ability to prevent vision loss from this condition, and I think we’ll have even better ways in the future.

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