Approximately 4.1 million Americans aged 40 and older have diabetic retinopathy. Nearly 899,000 people in this age range have vision-threatening diabetic retinopathy.

Diabetic retinopathy is a condition caused by diabetes that usually affects both eyes. Diabetic retinopathy affects one out of three diabetic patients. A high glucose level in the body can damage the tiny blood vessels in the light-sensitive tissue in the back of the eye, called the retina. A variety of eye problems may result from this, ranging from unnoticeable symptoms to blindness. The earliest stage of this disease is the most common and causes the least amount of vision loss.

How does diabetic retinopathy affect your vision?

The common symptom of diabetic retinopathy is that you end up with vision loss in certain areas of the eye. Most of the time there is not a complete change in vision, rather sections of the vision start to go, usually due to what can occur in the retinal vasculature. When your sugar levels are high, bleeding can occur causing patches in your vision where you cannot see well. Therefore, a lot of times it's more about being able to find areas where you see best using magnification and then focusing on the areas where you don't see so well.

Additionally, there are problems with contrast because with less lighting, the retina begins to lose some of its ability to see in some areas. This means that sometimes you are not getting the full effect of lighting. As a result, you are essentially almost blinded by the glare. People with diabetic retinopathy can benefit from using tinted glasses outside as well as indoors. In fact, using a tint to change how they see can be extremely helpful for them.

Are diabetic retinopathy's effects confined to the central vision or do they affect peripheral vision as well?

Both central and peripheral vision are affected by diabetic retinopathy. Diabetic retinopathy can also cause diabetic macular edema, which adversely affects your central vision to the point where you cannot see 20/20 any longer. Patches or areas with poor sight will usually be in the periphery. Therefore, diabetic retinopathy may cause central vision loss if the macula is affected and then there may be patches of vision loss in the periphery depending on where the bleeding occurs.

When does diabetic retinopathy affect your central and peripheral vision?

The changes in your central and peripheral vision generally occur when your sugar levels are not controlled for a long period of time. It is possible for diabetic retinopathy to go years without changes. When a person is unable to control their sugar levels, whether they're at high levels for a long time, or if there is a lot of fluctuation in their sugar levels, then this puts more stress on the vessels. As the uncontrolled diabetes progresses, it can also make it worse. You will see more of the true vision loss from diabetic retinopathy over time when you have uncontrolled diabetic retinopathy for many years.