Vision and Diabetes

Gretchen Becker Health Guide
  • One thing many people have heard about diabetes before they are diagnosed is that when you have diabetes, you may go blind.


    Of course this is true.


    It’s also true that when you don’t have diabetes, you may go blind. There are no guarantees of anything in this life.


    But because they’ve heard this about diabetes, people who are diagnosed with “fuzzy vision,” may panic, thinking they’re on the way to blindness.


    So it’s important to understand the difference between retinopathy, which can occur with longstanding diabetes and can lead to blindness if not treated, and temporary vision changes that can occur with high blood glucose (BG) levels.

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    I know about the latter, because they happened to me.


    I was diagnosed pretty late in my type 2 diabetes. My fasting BG level was over 300, I went over 400 after meals, and my A1c was about 13! [When I was diagnosed, they used a slightly different test called the A1, which gives higher numbers, and my A1 was 16.]


    The first sign I had that anything was wrong was that I got very myopic (nearsighted). I couldn’t read the signs along the road. And I had to hold books very close to my eyes. I hadn’t a clue that this might indicate diabetes, but, like most people, explained away the symptom with something else. I’d been copy editing a book written by an ophthalmologist. He’d used single-spaced copy with no margins (this was before most people had computers), so it was very difficult to read. The book was also very poorly written, and in order to meet the deadline I was working about 60 hours a week on it. I jokingly suggested that he was trying to drum up business by making all the editors squint.


    It was only after I realized I was thirsty all the time (which I explained away by the fact that I use a lot of salt) and running to the bathroom more often than I remembered I had in the past (which I explained away by the fact that I was drinking a lot of water) that a friend suggested I be tested for diabetes. The nurses took a long time with the urine test. They finally told me the sugar in the urine read so high they thought their machine was broken and had to recalibrate it.


    Because of all the high numbers, I went immediately on metformin. I also changed my diet drastically. And the numbers started coming down. It didn’t take long to reach fastings of about 120, and then a second metformin pill brought them under 100.


    But these rapid BG changes affected my eyesight a lot. I went from being myopic to being hyperopic (farsighted). I started using my former reading glasses to see someone sitting on the other side of the table, although I could see the distant mountains quite clearly. Then I started pasting the lenses of cheap drugstore reading glasses over my old glasses in order to drive. I looked a little odd, but at least I could see.


    This situation lasted for about 2 weeks, and then the farsightedness started to reverse, and after another couple of weeks my vision reverted to where it had been in the past, just slightly myopic.


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    My situation was probably extreme because I had such high BGs to begin with and they came down pretty quickly. But many people see this type of vision change when they are first diagnosed with high BG numbers.


    The important thing is not to panic. This doesn’t indicate impending blindness. It’s just your eyes adjusting to new BG levels.


    And it’s prudent not to rush out and get new prescription lenses while these changes are taking place. If possible, wait a month or so. If your employment requires perfect vision, ask your eye doctor for advice on coping with this without breaking the bank.


    Slight visions changes can also occur after diagnosis if you let your BG levels get high. Different people seem to be affected in different ways. Some find that a high BG level will cause immediate vision changes, and others see the vision changes 12 or 24 hours later. If this happens to you, it’s another incentive to keep your BG levels close to normal ranges.


    This type of vision change is caused by changes in the osmotic pressure in the lens that cause more fluid to enter the lens, changing its shape and refraction. Most people get more myopic, but a few report the opposite.


    The other kind of diabetic eye problem, retinopathy, can usually be prevented with normal or close-to-normal BG levels. It’s caused by tiny leaks in the blood vessels in the retina. If you develop early retinopathy, lasers can keep the condition from getting worse, although the treatment may reduce your peripheral vision.


    This is the serious type of diabetic eye problems, and it’s the reason you should see an ophthalmologist at least once a year, more if there are hints of retinopathy developing. And it’s a good reason to do whatever you can to control your BG levels. No tasty pizza or chocolate cake is worth losing your vision.


    Remember the wise words of William Polansky: “Diabetes causes nothing. It’s poorly controlled diabetes that causes complications.”

Published On: May 11, 2012