People living with diabetes are at significantly increased risk for sight-threatening eye problems compared with nondiabetics. These problems specifically include retinopathy, cataracts and glaucoma. According to the National Eye Institute, about 40 percent of U.S. adults with diabetes have diabetic retinopathy. That translates to 4.1 million Americans age 40 and older with diabetic retinopathy, a leading cause of blindness in the United States.
Nonproliferative Retinopathy
To understand eye diseases, it helps to know how the eye works. Think of your eye as a camera. Images come into the eye through the pupil (the black center of the eye) and pass through the lens, which focuses the images onto the retina. The retina is a collection of nerve tissues that capture the image signals and send them to the brain where they are recognized and understood. Diabetic retinopathy is a retinal disease caused by abnormalities in the blood vessels that supply the retina. Nonproliferative retinopathy is the early form of the disease. The diseased retinal blood vessels are weak and balloon out in areas called microaneurysms. With time, obstruction of the diseased blood vessels develops. The vessels may bleed or leak fluid, which interferes with the retina's ability to capture images. The blockages also deprive the retina of needed oxygen, which damages the retinal nerve tissue. People with nonproliferative retinopathy typically do not notice visual changes despite significant retinal disease. This is why it is important to have regular eye examinations if you have diabetes.
Proliferative Retinopathy and Retinal Detachment
Untreated nonproliferative retinopathy progresses to proliferative retinopathy. In this stage of the disease, the deficient blood supply to the retina triggers development of new blood vessels. However, the new blood vessels are defective; they bleed and cause scar tissue to form. The scar tissue may pull the retina off its base, a condition called retinal detachment. People with proliferative retinopathy experience problems with their sight, including blurred vision, black spots or flashing lights before their eyes, floaters (specks that float around in the visual field) and sudden loss of vision.
Cataracts
A cataract is clouding of the eye lens. Just as you cannot see clearly if your sunglasses are clouded by dirt and dust, clouding of the eye lens distorts normal vision. The American Diabetes Association reports that people with diabetes are 60 percent more likely to develop a cataract compared with nondiabetics. Symptoms of cataracts include blurred vision, poor night vision, needing an increased amount of light to see well and glare--the impression of halos surrounding bright lights. Decreased color discrimination is common, such as not being able to distinguish between dark blue and black.
Glaucoma
Ocular fluid is a gel-like substance that fills the eye. The fluid is in a constant state of turnover; new fluid is produced and existing fluid drains away. Glaucoma occurs when the ocular fluid drainage system is not functioning properly. Ocular fluid accumulates, causing increased pressure on the eye nerves, which damages them. The American Diabetes Association states that people living with diabetes are 40 percent more likely to develop glaucoma than are people without diabetes. Early glaucoma is asymptomatic. With disease progression, peripheral vision deteriorates; things straight ahead are seen clearly, but items at the edges of the visual field (the periphery) are unclear or unseen. Imagine looking at the world through a tube; this is similar to the visual loss that accompanies advanced glaucoma. Untreated or uncontrolled glaucoma is a leading cause of blindness in the United States.
