How does diabetes cause blurry vision?

Most of the time diabetes causes very little symptoms for the patient until the disease progresses because it hasn’t been checked or monitored regularly. When diabetes affects the eyes it is referred to as diabetic retinopathy and it can happen in two ways. The blood vessels of the eye that are affected primarily by diabetes can shut down or leak blood. If this happens the body’s response is to create new blood vessels that carry blood to the areas that are affected. In the rest of the body that is a useful thing but in the eye these new blood vessels can bleed. 

Inside the eye, we have a clear gel called vitreous where the light goes through and hits the retina, which is like a camera film that allows images to be captured. If these new blood vessels bleed then they do so into this clear structure. If you picture a fishbowl that is normally clear with a drop of ink in it, you can imagine that the clarity of that fluid is affected. That will significantly affect light being transmitted onto the retina and therefore cause the vision to be blurred.

The second way that blurred vision can occur is because of blood vessels becoming leaky from diabetes affecting the eye and the body. When these leak their contents, the fluid will make the retina, where most of the blood vessels are, less functional. The retina is the inside layer of the eye, which transmits light into sight and if there's a leakage at the central part of the retina (the macula) then it doesn't work as well. Therefore it will lead to the vision being blurred and affected.
 

When would I see an ophthalmologist?

One of the major problems with diabetic retinopathy is that it usually causes no symptoms until the disease is very far progressed. In the United Kingdom, anyone diagnosed with diabetes will be enrolled and offered an annual screening of their retinas with photographs. If you have a screening and the photographers are concerned, they will recommend visiting an ophthalmologist who has a specialist interest in diabetic retinopathy.

However, if you are concerned by your vision in between those screening tests, particularly if you're diabetic, you should go ahead and see an ophthalmologist without waiting. The blurred vision may well be caused by problems of diabetes in the retina which can potentially be treated by a specialist with an interest in diabetic retinopathy.
 

Can diabetic retinopathy be cured?

Diabetic retinopathy at the moment cannot necessarily be cured. One would hope that with regular screening of your retinas if you are diabetic, then any early changes can be picked up and any potential treatment can be given to mitigate or slow down the progression of the diabetic retinopathy. Really, the best form of maintaining the retinas and vision in the circumstance of diabetes is to be eating a healthier diet. It is important to lead a healthy lifestyle, ensuring a good diet and regular exercise. We know that controlling your blood sugar level and blood pressure level reduces the rate of progression of diabetic retinopathy. There's also some growing evidence that an active lifestyle in addition to a healthy diet potentially also slows down the progression of diabetic retinopathy.

In the future, there may well be treatments that come along to potentially stop diabetic retinopathy in its tracks, but at present these aren't available. Really the best advice is to control diabetes as best as possible: the blood sugar levels, blood pressure, cholesterol and by leading an active life.