What May Be Causing Your Blurry Vision After Eating

Blurry vision is usually one of the earliest symptoms of diabetes. For people who have not been diagnosed with the condition but have risk factors of diabetes, blurry vision after eating could indicate that they have diabetes. It should prompt them to seek an evaluation from their doctor to determine whether their blurry vision is caused by diabetes or something else.

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High Blood Sugar Can Cause Blurry Vision

After light enters the front of the eye, known as the cornea, it passes through to the lens. Both the cornea and lens work together to focus the rays of light onto the retina, which is 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.

Sudden high blood sugar following a meal can lead to blurry vision because the rapid increase in blood glucose causes an integral part of the eye, the lens, to swell. The swelling is caused by fluid moving in and out of the eye, and leads to changes in the shape of the lens and therefore changes in eyesight. When blood sugar levels return to normal, the lens returns to its original shape, and regular vision is restored. However, the effects can last for a couple of days.

High blood sugar following a meal is known as postprandial hyperglycemia. It has been shown that high carbohydrate intake is associated with the sudden increase in blood sugar levels following a meal.

Blurred Vision May Indicate Diabetes

High blood sugar (also known as hyperglycemia) is possible if you have normal or prediabetic blood sugar levels, but you should definitely see a doctor if you have blurry vision after eating and other 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, where high blood sugar causes damage to the retina. It can result in blindness if the diabetes remains uncontrolled. By getting diagnosed and starting treatment, people who have diabetes can lower their risk of developing diabetic retinopathy. Therefore, it's important to seek medical help as soon as possible.

However, symptoms associated with diabetes often go unnoticed because they can be either mild or nonspecific. Blurry vision after eating is a clear sign of diabetes.

Diabetes Symptoms
  • Urinating a lot, especially at night

  • Extreme thirst

  • Unexplained weight loss

  • Increased hunger

  • Blurry vision

  • Fatigue

  • Excessively dry skin

  • Numbness or tingling in the hands or feet

  • Slow-healing wounds or sores

  • More infections than usual

Diabetes Risk Factors
  • Family history

  • Being overweight

  • Being 45 or older

  • Exercising fewer than three times a week

  • History of gestational diabetes

  • Being African American, Hispanic or Latino American, American Indian, or Alaska Native

  • History of non-alcoholic fatty liver disease

  • Having prediabetes

Diabetic Retinopathy  

Diabetic retinopathy can happen in those with both type 1 and type 2 diabetes, and is typically associated with those who have uncontrolled diabetes. It is classified into two categories; nonproliferative and proliferative. There are four stages in total:

  • Mild nonproliferation with microaneurysms: This is the first and least severe stage. In this stage, blood vessels of the retina begin to swell in small areas, known as microaneurysms. During this stage, fluid can leak into the retina in small amounts, which can lead to swelling near the center of the retina, known as the macula.
  • Moderate nonproliferative with blood vessel blockage: This stage is characterized by an increase in swelling of blood vessels of the retina. Blood flow to the retina is blocked and prevents the retina from getting the nourishment (blood and oxygen) it needs. Blood and other fluids begin to build up in the macula.
  • Severe nonproliferative with blood vessel blockage: As the swelling continues, a larger part of the blood vessels in the retina begin to become blocked. The blood flow to the area decreases even more, and in an effort to fix the issue, the body starts to grow new blood vessels in the area. 
  • Proliferative with blood vessel growth on the retina: At this stage, new but weak blood vessels begin forming in the retina. These new blood vessels can also form on the optic nerve and iris. The fragility of the blood vessels increases the risk of fluid leaking into the macula, and vision problems such as blurriness and reduced field of vision become pronounced. In the most severe cases, blindness can occur.

In the early stages of the disease, diabetic retinopathy often presents with no symptoms at all. As it progresses, people may start to see dark spots in their vision, have blurred vision, and experience a change in the colors they can see.

Treating Your Blurry Vision 

Paying attention to what causes your blurry vision after eating can help prevent it from occurring. You may want to lower your carbohydrate intake and choose foods that cause a gradual increase in blood sugar levels.

If the 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. 

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 doctor 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 doctor about any concerns you may have regarding your vision.

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