Diabetic retinopathy, the most common diabetic eye disease, occurs when there are changes in the blood vessels in the retina. Sometimes, these vessels may swell and leak fluids, or even cover completely. In other cases, new abnormal blood vessels grow on the surface of the retina.
The retina is a thin layer of light-sensitive tissue that covers the back of the eye. The rays of light are focused on the retina, where they are transmitted to the brain and interpreted as images. The macula is a very small area in the center of the retina. The macula is the area responsible for detailed vision, allowing us to read, sew or recognize a face. The part around the retina, called the peripheral retina, is responsible for lateral or peripheral vision.
Diabetic retinopathy usually affects both eyes. People with diabetic retinopathy often do not realize the changes in their vision during the early stages of the disease. But as it progresses, diabetic retinopathy usually causes a loss of vision that in many cases can not be reversed.
There are two types of diabetic retinopathy:
Background or non-proliferative diabetic retinopathy (NPDR). Non-proliferative diabetic retinopathy (NPDR) is the earliest stage of diabetic retinopathy. When this condition exists, impaired blood vessels allow an escape of blood fluids into the eye. Occasionally, deposits of cholesterol or other fats from the blood can enter the retina.
Proliferative diabetic retinopathy (PDR)
Proliferative diabetic retinopathy (PDR) occurs primarily when many of the blood vessels in the retina become blocked, preventing a sufficient flow of blood. In an attempt to supply blood to the area where the original vessels have been capped, the retina responds by creating new blood vessels. This process is called neovascularization. However, new blood vessels are also abnormal and do not provide the retina with adequate blood flow. Often new vessels are accompanied by scar tissue that can cause the retina to wrinkle or detach.
Causes of Diabetic Retinopathy
When blood sugar levels are very high for long periods of time, the capillaries (small blood vessels) that supply blood to the retina may deteriorate. Over time, these blood vessels begin to filter out fluids and fats, producing edema (swelling). Eventually, a condition called ischemia may occur, during which the blood vessels may become clogged. These problems are signs of nonproliferative diabetic retinopathy (NPDR).
If the problems of a diabetic eye are not treated, proliferative diabetic retinopathy (PDR) can develop. An obstruction of blood vessels due to ischemia can lead to the growth of new abnormal blood vessels in the retina (neovascularization) and damage the retina, causing wrinkles or a retinal detachment. Neovascularization can even cause glaucoma, a damage to the optic nerve (the optic nerve carries images from the eye to the brain).
Strict control of blood glucose and blood pressure, as well as periodic visits to your ophthalmologist for a detection of diabetic retinopathy, are key to preventing the disease and loss of vision
Frequently, the patient is not aware of the disease until the damage is severe. Symptoms of diabetic retinopathy can be:
- Blurred vision and gradual loss of vision
- Vision of spots or "flying flies"
- Shadows or lost areas of vision
- Difficulty seeing at night
- Retinopathy can affect the macula (central area of the retina responsible for the detail vision) or its periphery.
- Depending on the area affected and the degree of development of the disease, specialists have different treatment options, such as laser photocoagulation, intravitreal injections or surgery (vitrectomy).
- Other visual complications associated with diabetes, such as glaucoma or cataracts, require specific treatments.