Diabetes is a disease that affects blood vessels throughout the body, particularly vessels in the kidneys and eyes. When the blood vessels in the eyes are affected, this is called diabetic retinopathy.
The retina is the thin layer that lines the back of the eye. It detects visual images and transmits them to the brain. Major blood vessels lie on the front portion of the retina. When these blood vessels are damaged due to diabetes, they may leak fluid or blood and grow scar tissue. This leakage affects the ability of the retina to detect and transmit images.
During the early stages of diabetic retinopathy, reading vision is typically not affected. However, when retinopathy becomes advanced, new blood vessels grow in the retina. These new vessels are the body's attempt to overcome and replace the vessels that have been damaged by diabetes. However, these new vessels are not normal. They may bleed and cause the vision to become hazy, occasionally resulting in a complete loss of vision. The growth of abnormal blood vessels on the iris of the eye can lead to glaucoma. Diabetic retinopathy can also cause your body to form cataracts more quickly.
The new vessels also may damage the retina by forming scar tissue and pulling the retina away from its proper location. This is called a retinal detachment and can lead to blindness if left untreated.
There are usually no symptoms in the early stages of diabetic retinopathy. Vision may not change until the disease becomes severe. An exam is often the only way to diagnose changes in the vessels of your eyes. This is why yearly examinations with an ophthalmologist are extremely important for anyone with diabetes. If your vision changes and you feel you are not seeing clearly, get in to see your eye doctor immediately.
If any hemorrhages are detected on your eye examination, a test called fluorescein angiography will often be performed. During the test, a harmless yellow dye called fluorescein will be injected into a vein in your arm. The dye will travel through your body to the blood vessels in your retina. A special camera with a green filter will be used to take multiple photographs. The pictures will be analyzed to identify leaky blood vessels, damage to the lining of the retina or the formation of new blood vessels. Swelling from leaking blood vessels can also be evaluated by an non-invasive imaging test called OCT.
It is occasionally necessary to treat the retinal swelling produced by diabetic retinopathy with a laser treatment. Additionally, injection of medication into the vitreous of the eye is sometimes indicated. If proliferative retinopathy occurs (when abnormal new blood vessels bleed into the eye), pan-retinal photocoagulation is performed. During this procedure, a laser is used to destroy all of the dead areas of retina where blood vessels have been closed. When these areas are treated with the laser, the retina stops manufacturing new blood vessels, and those that are already present tend to decrease or disappear.
If diabetic retinopathy has caused your body to form cataracts, they can be corrected with cataract surgery.