What Causes Blurry Vision After Eating?

The Link Between Carbs, Blood Sugar, and Vision

Blurry vision after eating occurs when a rapid increase in blood sugar levels causes the lens of the eye to swell. This changes the shape of the lens, thereby changing your eyesight. Blurry vision, in general, is often one of the earliest symptoms of diabetes.

People without a diabetes diagnosis who experience blurry vision after eating should see a healthcare provider—especially if they have diabetes risk factors. Left unchecked, diabetes can lead to serious complications, including blindness.

This article discusses the causes of blurry vision after eating and explains why it occurs. It also explains diabetic eye complications and treatments.

High Blood Sugar and Blurry Vision

Vision is a complex process. Light enters the front of the eye, known as the cornea, and passes through to the lens. The cornea and lens work together to focus the rays of light onto the retina, a thin tissue located at the back of the eye.

Retina cells then absorb that light and convert it into electrochemical impulses. They are then sent along the optic nerve and to the brain, where they are translated into the image you see.

Eating a meal high in carbohydrates can cause a sudden increase in blood sugar levels. This is called postprandial hyperglycemia. It happens as your body breaks carbohydrates down into sugars, which enter your bloodstream. Carb-heavy foods that may cause a blood sugar spike include:

  • Bread
  • Pasta
  • Potatoes
  • White rice
  • Baked desserts
  • Candy
  • Breakfast cereal
  • Sodas and other sugary beverages
  • ice cream
  • Fruit juice

Sudden high blood sugar causes fluid to move in and out of the eye. As a result, the lens swells, changing its shape, and blurring your vision. When your blood sugar levels return to normal, the lens returns to its original shape, restoring regular vision. The effects can last for a couple of days.

Other Symptoms of Diabetes

Blurry vision after eating is just one symptom you might experience if you have diabetes. Some others include:

  • Excessive thirst or hunger
  • Losing weight without trying
  • Fatigue
  • Numbness in your hands or feet
  • Dry skin
  • Excessive urination

Symptoms associated with diabetes often go unnoticed because they can be either mild or nonspecific. This is why it's important to see a healthcare provider for an annual exam, especially if you have risk factors for diabetes.

High blood sugar, also known as hyperglycemia, is possible if you have normal or prediabetic blood sugar levels. Still, make sure to see a healthcare provider if you have blurry vision after eating and/or any of these other symptoms.

Risk Factors For Diabetes

Type 2 diabetes is the more common type of the condition. About 1 in 10 Americans have diabetes, and 90% to 95% of them have type 2 diabetes. The risk factors for type 2 diabetes include:

Unmanaged diabetes can potentially lead to vision loss. People with diabetes are at risk of developing diabetic retinopathy. This condition occurs when high blood sugar causes damage to the retina. If diabetes remains uncontrolled, it can result in blindness.

Diabetes can be diagnosed with one of several blood tests. If your tests are normal, your healthcare provider may consider other potential causes for your blurry vision, such as allergies, migraine, a bacterial or viral infection, and medication use. 

Diabetic Retinopathy  

Diabetic retinopathy is an eye disease associated with diabetes. It can happen in those with both type 1 and type 2 diabetes, and is typically associated with those who have uncontrolled diabetes. Early diagnosis and treatment can lower your risk of developing diabetic retinopathy.

Diabetic retinopathy progresses through four stages. In the early stages, blood vessels in the retina begin to swell and leak fluid. Over time, the swelling increases, and fluids build up in the macula at the center of the eye.

In later stages, blood vessels become blocked and new blood vessels start to grow. Because these new blood vessels are fragile, they may leak more fluid into the macula, causing vision problems such as blurriness and reduced field of vision. In the most severe cases, blindness can occur.

Stages of Diabetic Retinopathy

Verywell / Jessica Olah

There are often no symptoms in the early stages of the disease. As diabetic retinopathy progresses, blurry vision may be a key symptom. You may also start to see dark spots in your vision and experience a change in the colors you can see.

Diabetic retinopathy can't be reversed. As it progresses, the damage to your vision will be permanent. However, you can prevent this by receiving a diagnosis and treatment in the early stages of the disease.

What To Do if You Have Blurry Vision After Eating 

If you experience blurry vision after eating, it's important to seek medical help as soon as possible. Blurry vision after eating is a clear sign of diabetes and should not be ignored.

Meanwhile, paying attention to what causes your blurry vision after eating can help prevent it from occurring. Try lowering your carbohydrate intake, and choose foods that cause a gradual increase in blood sugar levels.

You can also help keep your blood sugar in check by eating smaller, more frequent meals, drinking plenty of water throughout the day, and eating higher fiber foods.

If your rise in blood sugar is not associated with any serious symptoms such as shortness of breath, nausea, vomiting, or dry mouth, you could try exercising as a way to lower your blood sugar. The level of exercise does not have to be strenuous. Research has shown that just a 15-minute walk after every meal can help manage blood sugar levels for a 24-hour period. 

If you are already being treated for diabetes and you get blurry vision after eating as a new symptom, talk to your healthcare provider. Your diabetes management plan may need to be revised.

Summary

Blurry vision after eating is a symptom of diabetes. It happens because a spike in blood sugar causes fluid to move in and out of the eye, changing its shape.

If you experience this symptom, talk to your healthcare provider. Untreated diabetes can lead to complications like diabetic retinopathy, which may cause permanent damage to your vision.

A Word From Verywell

Blurry vision after eating can be a warning sign that you have diabetes. If you experience this, it's important that you make an appointment with your healthcare provider to find out whether diabetes or something else is causing the issue.

Uncontrolled diabetes can lead to serious eye complications and even vision loss, so it's better to take action early to address this problem and prevent it from becoming worse. Many people with diabetes are able to reduce their risk of developing diabetic retinopathy by managing their condition. Talk to your healthcare provider about any concerns you may have regarding your vision.

Frequently Asked Questions

  • Does blurred vision always mean diabetes?

    No. Blurry vision is a symptom of diabetes, but can also be caused by other things. Refractory errors, meaning you are nearsighted, farsighted, or have astigmatism, are one example.

  • Can digestive problems cause blurry vision?

    Possibly. Research links irritable bowel syndrome to dry eye disease. When your eyes are dry, it can become difficult to focus. Precisely why IBS can cause dry eye is unclear.

  • Can high blood pressure cause blurred vision?

    Yes, hypertension can lead to vision problems. High blood pressure can damage blood vessels in the retina, the layer of the eye that changes light and images into nerve signals sent to the brain. The damage occurs slowly over time. 

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10 Sources
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