Season 3 Episode 8: Understanding diabetes and vision loss: A walkthrough with Dr. Randy Kardon

In this episode Dr. Levi Sowers and Brandon Rea interview returning guest Dr. Randy Kardon. Dr. Kardon is a neuro ophthalmologist at the Iowa City VA Healthcare System and the University of Iowa in Iowa City who has had federal funding for over 30 years. This episode focuses on diabetic neuropathy and diabetic retinopathy. Diabetes affects many different types of body tissues, including the eye. With minimal invasiveness, the eye can be studied and provide information about how diabetes damages other tissues. Additionally, the eye can allow doctors to detect diabetes far earlier than other tissues with high resolution scans on the cells in the eyes. Early detection and management of diabetes can help minimize health effects of the disease and can prevent blindness. Control of blood sugar is the most important aspect to help prevent blindness with diabetes. Dr. Kardon explains how diabetes affects the eye and can lead to vision loss, as well as other effects on the body and available treatments. He explains that there are tiny blood vessels in the eye that are lined with endothelial cells. In diabetes these endothelial cells are damaged by the byproducts of high blood sugar and cause the tiny blood vessels to leak fluid into the tissue. When fluid gets into the tissue layers it disrupts the tissues' ability to function. This, however, can be managed with treatment. After the vessels begin leaking, the eye releases growth factors to allow new blood vessels to grow. Unfortunately, these vessels are weaker and begin to leak even more, and this is what leads to severe blindness in patients. Though there are treatments for the second stage of blood vessel leaks, when the leakage is too severe there is little that can be done. Dr. Kardon also talks about the different types of diabetes and how each type affects vision in patients.

If you are a Veteran or you know a Veteran needing help with visual loss, contact the Visual Impairment Services Team coordinator at your nearest VA medical center or contact the Blind Rehabilitation Service Program by phone which can be found here. There are 13 Blind Rehabilitation Centers around the country, which can help with things like mobility, communication, and living with vision loss. 

What is Vets First Podcast?

The Vets First podcast is a research-based podcast that focuses on the VA healthcare system and its patients. Instead of being just another research podcast, the Vets First podcast was created with a primary focus on the Veterans and their stories. The hosts, Levi Sowers PhD, and Brandon Rea work to bridge the gap between the state-of-the-art research being performed at Veterans Affairs and the Veterans themselves in an easy-to-understand manner. Importantly, Levi and Brandon want to assist researchers around the country to better understand the needs of Veterans. In this podcast you will hear interviews from Veterans with specific conditions and then hear from VA funded researchers who are studying those very topics as well as other highlighted services the VA provides.

The Department of Veterans Affairs does not endorse or officially sanction any entities that may be discussed in this podcast, nor any media, products or services they may provide.

Announcer: Welcome to the Vets First Podcast, a research-based conversation centered around the VA health care system, its services, and patients. From Iowa city, Iowa, here's your hosts: Dr. Levi Sowers and Brandon Rea.

Levi Sowers: Welcome back to the Vets First podcast. As always, Brandon is here.

Brandon Rea: Hi, everyone.

Levi Sowers: And today we have Dr. Randy Kardon, who's been a mirror ophthalmologist at the VA and the University of Iowa for roughly 30 plus years. He was a guest on season one, episode three. And today he's coming on to talk about diabetic neuropathy and diabetic retinopathy. Given this season is focused on visual research and an interesting factoid about Randy and it's quite impressive, is that he's been funded by either the NIH, VA, VA or DOD for over 30 years. And welcome to the podcast again. Randy, I really appreciate you coming on.

Randy Kardon: Thank you. Levi and Brandon, it's great to be here and to help bridge the understanding of diabetes between veterans and researchers and clinicians.

Levi Sowers: So, Randy, we're having you on today to talk about diabetic retinopathy. Specifically. We have a veteran named Loretta who spoke to us in pretty candid detail about her, the process of becoming visually impaired from from diabetes. And I think the first question I really want to get at is why does diabetes affect the retina in the way that it does, especially uncontrolled high blood sugar?

Randy Kardon: That's really a good question. I think the main point, it's not just about blood sugar. I mean, the high blood sugar and the condition of diabetes itself has different influences on different tissues of the body. You know, the main vital organs, such as the heart in the kidneys and the brain, but also sensory organs like the eye. And the reason we're talking about this is not just because that tragedy of untreated diabetes can cause some blindness, but the effects on the eye that can be monitored very carefully. And noninvasively tells us how diabetes might be affecting other tissues like the brain and the heart and the kidneys. And so that's one of the reasons the VA has a policy of examining, trying to make sure that veterans have eye exams of diabetes yearly with photographs of the retina to try to prevent it from getting out of hand and treating it early before it results in blindness. And from the veterans' side, we really feel badly for them because they can't feel that it's happening to their vision early on. They can't sense that something's going on in their eyes. They feel like everything's okay. And these early changes, once they're detected, if we can get the blood sugar under better control and there's ways of treating what's happening in the eye, it can prevent blindness. And so that's the main thing I want to convey, and I'll talk about how it happens. But veterans realize that it's not their fault. They just can't tell early on what's happening. But the eye doctor can because the eyes are a window into the brain and because it's a clear window, we can see the tissues in the back of the eye in very high resolution and detect the earliest, earliest changes. And that patient can even be aware of.

Levi Sowers: So if I'm a veteran and I get diagnosed with diabetes at some point, is it likely that I would have problems and my vision eventually? Is that something that's 100% well occur even if I control my blood sugar? Well, or we know.

Randy Kardon: That's a good question. We know that the very strict regulation of blood sugar and monitoring that through blood agency levels, we know that keeping that under very good control greatly reduces the risk of the complications of diabetes. There's no question. The scientific evidence is unequivocal about that. Nobody argues that. And so it's. But that's easier said than done because it's a change in lifestyle that veterans have to key into being, you know, obsessive compulsive about it almost, and watching what they eat. And newer ways of monitoring blood sugar non-invasively make it easier so they don't have to get a steak fingerstick every day. So there are better ways of monitoring this now. But the main point which you've brought up is that very good control of blood sugar greatly reduces the risk of complications and blindness. So does it go to zero? Probably not, but it goes close to zero. And it's also important that other nerves besides the ones in the back of the eye can be affected. The nerves that sense pain and sense touched in your hands and feet. Those nerves can be affected. And many diabetics suffer from peripheral neuropathy where they lose sensation. It's hard to balance themselves. They get sores on the bottom of their feet because of these nerves that are being damaged. You know, in recent studies by Dr. Mark York and myself and others have shown that lipids or fatty acids in the body that are also regulated by diabetes have an effect on these nerves. And one of the areas of research that's hot right now is taking fish oil capsules that contain the good fatty acids can not only prevent or reverse some of these peripheral neuropathy. So besides the retinopathy, there are other nerves that affect the quality of life and veterans that have to do with sensation and foot sores and ulcers. They're extremely important to getting back to the eye. What happens in the eye that causes type panic, retinopathy and vision loss is some of the early changes that these tiny little blood vessels that supply oxygen into tissue, they're line by a single layer of cells or tissue called endothelial cells that lines all blood vessels. And in diabetes, these endothelial cells seem to be damaged by the breakdown products of high blood sugar. And that causes these tiny blood vessels to leak fluid from the blood into the tissue. So it's kind of like the retina is a very highly organized sandwich of different layers of nerves that help you see it transmits it to the brain. And when fluid gets into those layers, it's kind of like a carpet getting water underneath it. It disrupts the ability, get the nerves to function. And so this leakage of fluid sometimes is the first thing that happens and that can be treated by certain injections in the eye that really is doesn't hurt, that can stop the leakage or sometimes small focal laser treatment to the blood vessels that are leaking. Can stop them from leaking. So the first stage is often tiny leakage of fluid. Some people have even found that the high blood sugar can damage the nerves in the retina themselves. But the main feature is the sleepiness that can occur. Then the next thing is when the retina senses not enough oxygen is being delivered, there are certain factors that are released to compensate and that causes new blood vessels to sprout and grow. And you think that they're a good thing because you're growing new blood vessels to supply blood to these areas that are being deprived, that the new blood vessels aren't normal blood vessels, they're fragile and they often bleed and blood gets into the cavity of the eye that causes the dramatic reduction in vision that can cause scarring and tugging on the retina and the retina is lifted off. And this is a severe cause of blindness. Why people lose vision completely. And there's complicated surgeries that can be done by specialists called retina surgeons. And often this can save some vision, but sometimes if it's discovered too late, then there's only a limited amount that can be done. And that's the tragedy. So that's the series of events that why it has to be detected early and treated early to get on top of it so that we don't get this tragic loss of vision eventually by detecting it early.

Levi Sowers: And Randy, does the do you normally when you see leakage in the eye like this, does it affect both eyes equally or do sometimes see more and one than the other?

Randy Kardon: That's a good question too. Most of the times it affects both eyes, but sometimes it can affect one eye more than the other. And actually another complication of diabetes can lead to that. So I mentioned diabetes not only affects small blood vessels that can affect large blood vessels like the carotid arteries in the neck that supply blood not only to the eye, to the brain. And if one of those arteries gets very narrowed because of the effect of diabetes with atherosclerosis and decreased blood flow occurs to the eye, that can cause an asymmetric effect on the retina tissue, too. So sometimes an asymmetric effect is a warning sign that we have to look at the large blood vessels too, not just the tiny ones in the eye.

Levi Sowers: And is this do you see diabetic retinopathy with both type one and type two diabetes?

Randy Kardon: So that's a good question. So type one diabetes, some people call that juvenile diabetes. That's the one that's usually discovered earlier in life where there's a definite problem with the production of the insulin in the pancreas that controls blood sugar. Type two we see later in life and for reasons that are being studied, obesity and weight gain is a very big risk factor. In that case, insulin is being produced, but the tissues seem to be resistant to the insulin effect. So this end, organ resistance to insulin so that even though insulin is being produced, its effect is being blocked somehow and that's what causes some similar complications. And that's the type that's more common among veterans and among prevalent among the civilian population, too. And that's why veterans, doctors are always saying if you could just lose some weight besides controlling your blood sugar, a lot of these problems will be greatly reduced because weight loss control will reverses this insulin resistance often.

Levi Sowers: Interesting. So you were talking a little bit about lipids, different types of fats. Lipids are fats and there's good fats and there's bad fats as extensive research from many decades on that. You talked about how some good fats can help reverse some of the possibly reverse some of the damages that are caused in the peripheral. So like in your hands and your feet in your legs, can the same thing happen with the eye? So that's a very good question, too. And one of the ways that affects the eye is the same. Tiny nerves allow you to sense, you know, pain and vibration and touch in your fingers and hands. The cornea, which is the front part of the I like to watch glass cover. The eye is loaded with these nerves. Matter of fact, the cornea is probably the most sensitive part of the body because the nervous system needs to sense that something's irritating the front surface to make you blink or that tell you something's wrong. And so the same nerves that are affected by diabetes in the hands and the feet affect the corneal nerves, too. And that's a good thing. And a bad thing. The bad thing is that when those nerves are affected, the surface of the cornea can get irritated and get rough and then that can blur vision. Even though the retina is functioning fine. It's like the covering of your eye is now roughened up. And so the image is blurred as it goes through and that's reversible and treatable. The good part is that those nerves act as a window or as a way of monitoring the other nerves in the body so we can objectively monitor how well those nerves are working. What do I mean by that? So sodium chloride, which is the salt comes in solution in an eye drop that you can put in the eye at a higher concentration. And when you put a drop of that and normal eye, it's mildly irritating, somewhat blinks for about 20 to 30 seconds when the nerves are functioning normally, but when the nerves are not functioning and the sensation is getting reduce putting the same drop in a diabetic sigh, they don't hardly blink afterwards and we can monitor that with that low cost video system. And actually quantify how much they're blinking. And this is a way of monitoring how well those nerves are working. And so that's one of the areas of research we're working on. We found in animal models of diabetes, this works beautifully and we can look at the effect of these good lipids on reversing the nerve dysfunction. And now we're studying the same thing in humans.

Levi Sowers: When you say that they don't respond as much, is that because the nerves are less sensitive or they're becoming they just don't respond in a way that would cause a person to blink?

Randy Kardon: So usually they're becoming less sensitive and there are different types of sensory nerves. Some other types of nerves become more sensitive and cause pain. And just like the nurse in that field, in the hands, you can lose sensation, but at the same time it becomes painful. So it's kind of a dichotomy. You have to understand there's different classes of nerves that have different functions and they can be affected by diabetes in different ways.

Levi Sowers: What Is there any other thing we want to get across to veterans today about diabetic retinopathy? You know, one thing that you told me about just a bit ago is that how they don't notice it changing over time. So I think it's really important for veterans with diabetes to get in, get their vision checked. And I have something that relates directly to this. My dad had uncontrolled type two diabetes and we didn't know it for a long time. He was having a bunch of problems from it. And finally a young med student in his little town we were at, he was doing his rotation there. It was like, I'm going to check your blood sugar and found that it was like, through the roof is a one. See, it was like 15 or something was really high. And when we got his blood sugar under control, my dad's first thing was like, I can see better. He was having really bad visual problems, but he didn't notice it. Corrente Why don't veterans notice or individuals at all notice the change in their vision over time when they have diabetic retinopathy? What? Why can't they notice that change and vision and loss of vision?

Randy Kardon: Well, part of it is because it's so subtle and gradual, it's often not abrupt. And so it's just like patients are developing mild cataracts almost, is that some of the changes are happening so slowly, even before you know it. You can't read road signs, but you don't realize when it was happening because it's just little by little. Now, some times large fluctuations in blood sugar can cause the lens in your eye to momentarily swell to cause big changes in a person's eyeglass correction even during the day. And those patients notices wide fluctuations, but often it goes away. So they think, oh, I'm okay. It went away. And so you tend to people deny they're worried. They don't want anything bad to happen. So they tend to deny if it's getting better again, that nothing happened. And so there's this denial, too, that we're all, you know, guilty of with health problems. It's nobody's fault. It's just we don't want anything that having that happening to us. So we kind of ignore it.

Levi Sowers: So you're saying how these changes are slow and kind of gradual, and when you have as visual acuity, acuity slowly dropping, is there a ballpark time period where you see from like early on stages to to like severe vision loss? Like I know it sounds like it can differ depending on how well blood sugar is regulated, but is there like a ballpark time frame where you kind of see this shift?

Randy Kardon: So that's another very good question. We see across all diabetics. It's extremely highly variable. I mean, some have rapidly accelerated complications over just the course of a year. Some may occur slowly, gradually over years. And a lot of people are studying the whole genetic aspect is why do some diabetics respond much faster, you know, to the complications and others and if we could understand that, that might lead to also a trail for new treatments, you know that what are the metabolic pathways that modulate the rate at which this is happening? And there are lots of new treatments that are coming on board. That's why I want to leave this podcast with some optimism here. So it's not only detecting it early, but some veterans say, So what are you going to do about it? You detect it early. There are a lot of new drugs to treat the metabolic condition, not only in the eye, but other organs, the whole condition of diabetes that are coming online and are being used effectively. And there are different treatments specifically for focusing on the end organ, like the eyes that are not risky, that are been proven to work. And so there are treatments for this. And so it's a dual responsibility of the veteran to make sure they make their appointments and take this seriously and for the doctors to inform the veterans about what we can do about it. And don't lose hope. There is hope and thanks to the VA health care system and the research funding, there are a lot of great doctors and researchers that are working on this tirelessly and they're making progress. So that's all I want to leave your listeners with that note.

Levi Sowers: Absolutely. We've already done this with you once, but we always ask a funny question at the end. I think it's important. So I think this time I'm going to tell the listeners a little bit about Randy. He's an avid golfer, and I heard that he's very good at golfing. I would like to know what your favorite golf courses are.

Randy Kardon: Pretty good. Well, some of my patients know that I spend part of the Iowa winter in Hawaii, island of Kauai, which is paradise. And so it's hard to compete with their golf course that's facing the ocean there. And also, you can see mountains through some of that course and just that easiness and laid back culture of the Hawaiian culture that is paradise and beauty. There are nice golf courses in Iowa, but I would say my favorite golf course is in the islands of Hawaii.

Levi Sowers: Think I'd rather stare at the ocean than the cornfields. That's just me. So I want to thank you. I think it's really fascinating. I did not know you have had 33 years of funding. That's really impressive from a research standpoint. A lot of that centered on veterans. And thank you for that. I think that's really, really, really cool.

Randy Kardon: So we're also working with great collaborators like you and mentoring young people and helping make them successful. That's the most fulfilling part of it.

Levi Sowers: Yeah, Yeah. I agree with you. And I think that the veteran is a really important aspect to that too. And you've done a lot.

Randy Kardon: I love treating veterans. I love understanding and helping them and it's very gratifying. And the VA has done more for me than I've done for the VA itself.

Levi Sowers: Thanks, Randy.

Announcer: This concludes today's Vets First Podcast. For questions or comments relating to the program, please direct email correspondence to [e-mail]. Thanks for listening!