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| How Diabetic Retinopathy Affects Vision |
The longer you have diabetes, the more likely it is you'll develop diabetic retinopathy. After having type 1 diabetes (formerly called juvenile or insulin-dependent diabetes) for 20 years, almost everyone with this condition has some degree of retinopathy. After the same number of years, more than 60 percent of people with type 2 diabetes (formerly called adult-onset or noninsulin-dependent diabetes) have some degree of retinopathy. Initially, most people with diabetic retinopathy experience only mild vision problems. But the condition can worsen and threaten your vision. Diabetic retinopathy is the leading cause of legal blindness among adults in the United States.
The threat of blindness is scary. But there's more cause for hope than for alarm. With early detection and treatment, the risk of severe vision loss from diabetic retinopathy is less than 5 percent. And you can take steps to protect your sight if you have diabetes. Start with a yearly eye examination. Work to keep your blood sugar and blood pressure under the best possible control.
Types
There are two types of diabetic retinopathy. Usually both eyes are affected, although the disease may be more advanced in one eye than the other.
Nonproliferative diabetic retinopathy
Nonproliferative diabetic retinopathy (NPDR), also called background diabetic retinopathy, is an early stage of the disease. It's the most common type of retinopathy, and symptoms are often mild.
In NPDR the walls of blood vessels in the retina weaken. Tiny bulges called microaneurysms (MY-kroe-an-yuh-riz-umz) protrude from the vessel walls. Another term for this is outpouching. The microaneurysms may begin to leak, oozing fluid and blood into the retina. As NPDR progresses, other signs of damage appear. These include patches of swollen nerve fibers, which are called cotton wool spots because they look like fluffy wisps of cotton.
Mild NPDR may not affect your ability to see clearly. Vision problems from more severe NPDR are usually the result of swelling of the macula (macular edema) or the dosing of capillaries, which reduces blood flow to the macula (macular ischemia). When the macula can't function properly, your central vision decreases. Your peripheral vision usually remains normal.
Proliferative diabetic retinopathy
Proliferative diabetic retinopathy (PDR) is the more advanced form of this disease. About half the people with very severe NPDR progress to PDR within 1 year. Retinopathy becomes proliIerative when abnormal new blood vessels grow (proliferate) on the retina or the optic nerve. The blood vessels also grow into the vitreous, the clear, jellylike substance that fills the center of the eye.
This abnormal growth follows the widespread closing of capillaries in the retina due to high blood sugar levels. The condition can cause vision loss affecting both your central and peripheral vision. The new blood vessels may leak blood into the vitreous, which clouds or even blocks your vision. Other complications include detachment of the retina due to scar tissue formation and a form of glaucoma associated with the growth of abnormal blood vessels on the iris.
Signs and symptoms
In the early, most treatable stages of diabetic retinopathy, you usually experience no visual symptoms or pain. The disease can even progress to an advanced stage without any noticeable change in your vision. Symptoms of diabetic retinopathy can include:
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| How Diabetic Retinopathy Affects Vision |
- "Spiders," "cobwebs" or tiny specks floating in your vision
- Dark streaks or a red film that blocks vision
- Vision loss, usually in both eyes, but more so in one eye than the other
- Blurred vision that may fluctuate
- A dark or empty spot in the center of your vision
- Poor night vision
- Difficulty adjusting from bright light to dim light