Diabetes Self-Management Blog

You probably know that eye damage (retinopathy) is a major complication of diabetes. So when vision blurs, it’s normal to think the worst. But diabetes can cause blurred vision in several other ways, some of which are reversible.

I’m embarrassed to admit I only recently found out that blurred vision is a symptom of diabetes, even without any retinal damage. When blood glucose levels go up, blood gets thicker. Thicker blood pulls in more fluid from surrounding tissues, including the lenses of the eye, impacting the ability to focus.

According to WebMD,

[Blurred vision] could just be a temporary problem that develops rapidly and is caused by high blood sugar levels. High blood sugar causes the lens of the eye to swell, which changes your ability to see.

Changing the shape of the lens naturally throws off vision. This can be a chronic, 24/7 kind of problem, or it can occur only after a high-carb meal, when glucose is way up. The Harvard Medical School Family Health Guide says that after-meal blurriness can be prevented by avoiding high-carb meals.

The cure for chronic, all-the-time blurriness is to get blood glucose down to normal range before meals. It may take as long three months of relatively normal blood glucose levels before vision returns to your baseline normal.

Diabetes can also cause blurriness or double vision due to hypoglycemia (low blood glucose). In this case, lens shape is probably not to blame. Low blood glucose can make it hard for the brain to focus on what the eye is seeing. Vision usually returns to normal when glucose levels rise.

If blurriness doesn’t go away when glucose levels are close to normal, you might have retinopathy. That’s a condition in which high glucose levels damage the blood vessels in the retina, or the back of the eye, which can cause blindness. Fortunately, it’s preventable and treatable.

The American Diabetes Association (ADA) suggests that people with diabetes have regular “dilated” eye exams. Dilated means a drop will be put in the eye to open the pupil wide, so an examiner can see all of what’s inside. ADA’s guidelines include:

• An annual dilated eye exam if you are between 10 and 29 years old and have had Type 1 diabetes for at least 5 years. (Those with Type 2 are recommended to receive a dilated eye exam shortly after diagnosis.)

• An annual dilated eye exam if you are 30 or older, no matter how long you’ve had diabetes.

• A dilated eye exam if you are pregnant or planning to get pregnant.

• A dilated eye exam if you experience any changes in your vision.

High blood pressure can also cause vision problems by damaging the optic nerve or through brain damage resulting from stroke. High blood pressure is very common in diabetes, so it’s important to keep blood pressure close to normal range as well.

Other eye problems can cause blurriness and blindness. These include age-related macular degeneration (AMD). In AMD, the retina gradually stops working for no clear reason, though some studies have found people with diabetes are more likely to have AMD. According to AMD.org, eating more green vegetables is one way to try to prevent AMD.

Cataracts are strongly associated with diabetes. They are a clouding of the lens in the eye that affects vision. It is thought that proteins in the eye fluid clump up for some reason and cloud the lens. Cataracts are more common in people with diabetes and in smokers. The National Eye Institute says that eating leafy green vegetable and keeping direct sun out of your eyes are good prevention measures.

In general, keeping near-normal blood glucose and eating right seem crucial to eye care. Writing in Diabetes Self-Management, Linnea Hagberg, RD, suggests “consuming leafy green vegetables like spinach, kale, collards, and broccoli.”

Hagberg also recommends corn, kiwifruit, red grapes, spinach, zucchini, yellow squash, orange peppers, orange juice, egg yolks, and Vitamin E as being good prevention for AMD and cataracts. For general diabetes eye health, she says:

• Wear sunglasses that protect the eyes from ultraviolet rays.

• Keep blood glucose under control.

• Stop smoking or cut back as much as possible.

• Choose brightly and deeply colored fruits and vegetables as often as possible. Include leafy green vegetables in your meals several times a week.

• Include plenty of vitamin C in your diet by choosing several daily servings of foods such as cantaloupe, strawberries, citrus fruits, kiwifruit, mango, papaya, broccoli, Brussels sprouts, sweet peppers, tomatoes, and cauliflower.

• Eat fatty fish two or three times a week. Limit total fat and commercially processed baked goods and snack foods.

• Have an annual eye exam (unless your doctor advises a different schedule) that includes dilating the pupils.

Have you experienced visual changes at different glucose levels? I’d be interested in hearing about it.

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Comments
  1. Lest we forget, blurred vision that gradually appears can also be a sign that your eyewear prescription has changed, and it’s time to get new glasses/contacts.

    Posted by Joe |
  2. Great reading on your site! I was searching for articles on the effects of anesthesia on BGLs, stumbled on this site. I’ve been elevated post some eye surgeries. I’m a grim tale fighting for my limited sight, and could pose for your diabetic eye damage poster child poster. I had yet another vitrectomy two days ago and have been doing slightly better BGL wise than my prior 10 surgery’s. He had to do another 1000+ laser points inside with a chaser of Lucentis. This is an attempt to save this eye from removal, sigh! (Yes, I use adaptive technologies to participate in this forum) Up until today then it kind of jumped up in the 240 range with a mind of it’s own. The anesthesiologist told me it would probably be elevated after the cocktail he used for the last surgery 3 weeks ago, and it was. This time I had a delayed reaction, over a day? But he told me not to chase it too hard with insulin. It’s still a white knuckled stressful experience to me all the same.
    Like you folks, just when I think I’m doing everything right with diet exercise and dosing, like it’s an exact science (A1C- 6.1- 6.3) since my diagnosis in 2009, yeah right, this hideous disease proves to me it’s a mysterious art form and bucks me on that pesky roller coaster ride. It leaves me thinking darn, is this Flexpen or BG meter broken or something? Not!
    All the calculations of carbs and sliding scale units, sometimes I feel OCD autistic, sigh!
    Another point I’d inject on your excellent article on eye care on blurriness symptoms. In addition to your recommendation of frequent dilated eye exams by a skilled ophthalmologist. I’d suggest your eye exams be earlier in the day, particularly your refractory exams for corrective lenses. schedule your exam on a good stretch of your BGL levels at optimal stable range. Nail your BGL for the exam and those new lenses. Check it in the chair, be on the markThat blurriness that you speak of might very well indicate your being in an un-healthy BGL range in the future. As you mentioned the effect on the inner ocular lens as well as any edema around or behind the retina could change your eyes focal point.
    Best wishes and be well!

    Posted by Jon Hart |
  3. I have been a diabetic for at least 10 years. It has been out of control up until recently. Normally, when my diabetic levels are high I get blurred vision. Now that my A1C levels have decreased where its getting under control, I am having blurred vision. My numbers for the past couple of months have ranged from 58 to 166. Went to the eye Doctor about my blurred vision and she informed me that she didn’t see any problems, therefore, it must be related to my diabetes being out of control for so long. Now when my numbers are low to normal, I have blurred vision. I am hoping that once I am under control for maybe 6 months that the blurred vision will cease; so far, its only been 2 months under control. The Doctor has increased my insulin dosage to ensure that it stays under control. I don’t agree (although I still do as advised, but when it’s 58, I won’t take any insulin at all.

    Posted by Roberta |
  4. Thanks for the great information. Something I’ve been struggling with is blurred vision after drinking tea. Whether it’s green, black, decaf, or even herbal teas, I get blurry vision after drinking tea. I think I get it a little after coffee, but it takes more coffee than tea to make it blurry. I thought it was the caffeine raising my blood sugar, but as I’ve said it even happens with caffiene-free teas. To be sure, I have tested numerous times and my blood sugar has been in normal ranges when the blurriness occurs.

    My endocrinologist and opthamologist both know of my symptoms, medications, suppliments, diet, and health, and don’t have an answer for me. I have had Lasik Eye surgery, and that eye doctor couldn’t figure it out either when I used to see him. Every time I get an exam, I have 20/20 vision or slightly better, even despite episodes of blurriness earlier that week or what have you.

    The blurry episodes haven’t been a problem before being diagnosed with type 1 diabetes. I am 29 and found out about 5 years ago. Not sure when I got the disease, but I believe it to be late-onset around 22 or 23 years old. The sudden problem with diabetes made me think it could be a drug side effect (insulin, or I also take lisinopril and synthroid), but the fact that it occurs within 1/2 to 1 hour after drinking tea makes me think otherwise.

    Blurriness occurs other times when I am not drinking tea, but I haven’t been able to isolate what food, behavior, or physiological condition(s) are associated with those episodes.

    Posted by Drew |

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Eyes & Vision
Focus on This: May Is Healthy Vision Month (05/14/13)
Drug Improves Vision in Diabetic Retinopathy (11/30/12)
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