Diabetic retinopathy is an eye condition that can affect the retina in patients who have had diabetes for many years. It is a major cause of poor vision and blindness. Although not totally preventable, when it is diagnosed early it can be treated early and be less damaging to vision. Even though the macular area is no larger than a pinhead, it contains the visual cells for seeing straight ahead, fine detail, and color. If the macula is damaged — or degenerates, as from AMD — central vision is interfered with. So when you look at an object, part of it may seem distorted, blotted out, or shrouded in a dark haze.
What is Retinopathy?
The term retinopathy means “a disease process that affects the retina.” The retina is the light-sensitive membrane that lines the inside back wall of the eye. It works pretty much like the film in the back of a camera. It receives images formed by the optical parts at the front of your eyes, then instantly “develops” them and sends them on to the brain, which does the actual seeing. When the retinal “film” is damaged, vision is often impaired. There are two types of retinopathy: background retinopathy, the milder form, and proliferative retinopathy, which is more serious. Neither type, on its own, is likely to cause any pain, but the proliferative form can lead to other eye problems that might cause pain.
Early changes are subtle and only slightly different from normal. There are usually no symptoms. Some of the retinal blood vessels gradually enlarge; some become irregular in size and develop some tiny weak spots (microaneurisms), which are the hallmark of this condition. They begin to leak exudates (fluid, fat, and protein) and blood. At first, depending on where leaks are located, they may affect vision only slightly and maybe not at all, but if they progress they are more likely to cause some reduction or distortion of vision. The condition varies over time, sometimes getting better for a while and then worse, but tending to slowly worsen. As it advances, some of the smaller retinal blood vessels gradually become obstructed, resulting in a patchy loss of retinal nourishment. In some patients this leads to the development of proliferative retinopathy.
The name “proliferative retinopathy” comes from the new, abnormal blood vessels that begin to grow (proliferate) over the surface of the retina and optic nerve, the “cable” that transmits images from the eye to the brain. It is thought that they form in an attempt to nourish the areas of “starving” retina. Unfortunately, these blood vessels are fragile, and they frequently break and bleed. (The bleeding can cause a sudden appearance of floaters.)
If the bleeding is into the vitreous (the gel-like fluid in the center of the eye), vision can become clouded from the blood. At first the blood is rapidly absorbed, so vision tends to clear in a few weeks. But eventually, with re-bleeding, vision may not clear so rapidly or even at all. As more new blood vessels grow, the risk for more bleeding increases. Scars form and may tug on or even tear the retina, which can lead to a retinal detachment. All of these developments have the potential for leading to blindness. Diabetic retinopathy is one of the major causes of defective vision and blindness in our country today. If you have diabetes, make sure you have a thorough eye exam at least every year (more frequently in advanced cases), and you should always take the best possible care and control of your diabetes.