Also known as diabetic eye disease, diabetic retinopathy is an eye disease that people with diabetes might develop. In fact, diabetic retinopathy affects nearly one-third of all adults over the age of 40 who have diabetes, according to the Centers for Disease Control and Prevention (CDC). In all, about 4.2 million adults in the United States have diabetic retinopathy and 655,000 have vision-threatening form of the disease.
Diabetic retinopathy (DR) can damage the blood vessels and tissues in the back of the eye. Diabetic retinopathy can cause significant vision loss and can even lead to blindness if left untreated, according to the American Optometric Association (AOA).
The word “retinopathy” refers to any type of damage to the eye’s retina, which is the light sensitive tissue lining the back of the eye. Carrying visual information about the outside world, light enters the front of the eye through the lens, which focuses the light. The light strikes the retina, which has special photoreceptor cells that absorb the light and the information it carries. The photoreceptor cells convert the light and information into signals that the brain can interpret into visual images.
The retina contains a large amount of blood vessels, which supply it with the oxygen and nutrients the photoreceptor cells and retinal tissue needs to function. Damage to these blood vessels can prevent the photoreceptors and retina from working well, resulting in cloudy or blurred vision. Left unchecked, damage to blood vessels can even lead to vision loss.
One small but important spot of retinal tissue, known as the macula, sits at the center of the retina. The macula is responsible for seeing detailed objects straight in front of the eyes and for color vision. Damage to macular tissue can cause loss of center vision, which makes reading, threading a needle and other close-up work difficult. Seepage of blood from the blood vessels can cause the macula to swell, resulting in blurred central vision.
Symptoms of Diabetic Retinopathy
Symptoms of diabetic retinopathy include:
- Spots or “floaters” in the field of vision
- Blurred vision
- Blurred central vision
- Difficulty seeing well at night
- A dark spot at the center of vision
How Diabetes Leads to Retinopathy
Diabetes is a condition associated with high blood sugar levels. Excessive amounts of sugar in the bloodstream can damage blood vessels within the retina. This damage can cause the blood vessels to swell and leak. Damaged blood vessels can even close off completely to prevent blood from flowing to the retinal tissue. In an effort to supply the retina with the oxygen-rich blood it needs, new blood vessels may form on the surface of the retina. These blood vessels can also leak into the back of the eye to block vision. All of these changes can lead to vision loss.
High blood sugar levels, known as hyperglycemia among medical professionals, can have other negative effects. Long periods of hyperglycemia can cause sugar to accumulate in the eye’s lens, for example, and this accumulation can actually change the curvature of the lens to change vision. As blood sugar levels go down, the lens returns to its normal shape and vision improves.
People with diabetes who maintain good control over their blood sugar levels can slow the onset and progression of diabetic retinopathy. Taking prescribed medications as directed, eating the recommended diet, exercising regularly, controlling blood pressure, and avoiding tobacco use and alcohol consumption can help too.
Types of Diabetic Retinopathy
Diabetic retinopathy is a progressive condition, which means it worsens over time. Eye specialists classify diabetic retinopathy according to the stages of the disease and the symptoms.
Non-proliferative diabetic retinopathy (NPDR) is the early phase of diabetic retinopathy; symptoms are mild or nonexistent. At this stage of the disease, the blood vessels within the retina are weak, and tiny bulges may appear. These bulges can leak blood into the retina and this can lead to swelling of the macula, a condition known as macular edema. Macular edema is the most common cause of vision loss among people with diabetes. Tiny particles, known as exudates, may form in the retina to affect vision.
The more advanced stage of DR is known as proliferative diabetic retinopathy (PDR). As the disease progresses, poor circulation from damaged blood vessels deprive the retina of the oxygen it needs to function well. This triggers the growth of fragile new blood vessels in the retina. The abnormal blood vessels can also grow into the gel-like vitreous fluid that fills the back of the eye, and potentially leak blood into this vitreous fluid to cloud vision. If the blood vessels bleed only a little, they may cause a few dark “floaters” in the visual field. If they bleed a lot, they might block vision completely.
The abnormal growth of blood vessels in PDR can form scar tissue that can cause problems with the macula or even lead to a detached retina, which is a serious emergency that occurs when the retina pulls away from the back of the eye.
Blood vessels can grow near the area of the eye that drains fluid from the eye. These vessels can block drainage and increase pressure inside the eye, and this increased pressure can damage the optic nerve.
Supports and Aids
A comprehensive dilated eye exam is the only way to determine if someone’s diabetes will cause blindness, which is why the AOA recommends that everyone with diabetes undergo such an exam at least once a year. Early detection and treatment can limit the potential for significant vision loss.
Treatment depends largely on the extent of the disease. Laser surgery can seal leaking blood vessels and prevent other blood vessels from leaking. Injection of medications into the eye can decrease inflammation or stop the formation of abnormal blood vessels. Certain surgical procedures can remove and replace the vitreous fluid in the eye; other surgical procedures can repair retinal detachment.
Low vision assistive technology can help people with vision loss associated with diabetic retinopathy. The most advanced low vision aids, such as eSight, combine the power of high tech cameras, smart algorithms and high-resolution screens to create sharp, real-time images.
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