A degenerative eye disease that occurs in people with diabetes, diabetic retinopathy can lead to severe vision loss or blindness if left untreated. Unfortunately, diabetic retinopathy remains incurable. However, it is treatable and preventable. In order to detect and prevent diabetic retinopathy, it is important that diabetes patients understand the causes of the disease, as well as any additional risks to the health of their eyes.
What Is Diabetic Retinopathy?
For people with diabetes, high blood sugar is a serious health problem. Because diabetics are unable to adequately absorb and process sugar, too much blood sugar can lead to kidney, heart, nerve, and eye damage.
Diabetic retinopathy occurs when the tiny blood vessels, known as capillaries, within the retina are damaged. In patients with non-proliferative diabetic retinopathy (NPDR), the walls of the capillaries weaken and develop microaneurysms, or tiny bulges protruding from the blood vessels. Eventually these microaneurysms begin to leak blood and fluid into the retina, causing vision loss.
In patients with proliferative diabetic retinopathy (PDR), not only are there progressively more microaneurysms, but new, abnormal capillaries begin to develop within the retina. As these blood vessels spread throughout the retina, they often begin to grow into the jelly-like substance (vitreous) that fills the center of the eye. Ultimately, this abnormal growth causes the capillaries to shut down, leading to vision loss and, in some cases, retinal detachment.
Diabetic Retinopathy Risk Factors
Patients with type I and type II diabetes are at a high risk of developing diabetic retinopathy. How much the disease progresses and spreads is in almost direct correlation to how long the patient has had diabetes and how long they have gone without consistent eye examinations.
Diabetes is currently the number one cause of new cases of blindness in the United States; serious complications from diabetic retinopathy affect approximately 24,000 new people each year. However, studies also show that given adequate preventative measures and the right diabetic retinopathy treatment plan, severe vision loss can be reduced by as much as 94 percent. So while all diabetes patients are at risk of developing diabetic retinopathy, not all of them are destined for blindness. Undergoing yearly eye exams and tests for diabetic retinopathy diagnosis are crucial steps to preventing total vision loss.
In addition to diabetes, there are several other risk factors that can contribute to developing diabetic retinopathy:
Poorly controlled blood sugar levels, which catalyze the formation of microaneurysms in the retinal capillaries
- High blood pressure
- High cholesterol
- Hispanic patients with diabetes
- African-American patients with diabetes
Symptoms and Diagnosis
One of the most frightening aspects of diabetic retinopathy is that most patients do not experience any symptoms or pain until the disease has begun to proliferate. This is why consistent preventative care and early diagnosis is so important. A trained medical professional must perform a series of tests and a comprehensive eye examination to determine if you have diabetic retinopathy. Learn more about diabetic retinopathy symptoms and diagnosis.
Types & Progression
As diabetic retinopathy progresses, vision impairment often occurs gradually; however, sometimes patients experience more sudden changes in vision.
The first stage of diabetic retinopathy, known as non- proliferative retinopathy or background retinopathy, often has no noticeable signs or symptoms, although retinal swelling may be present. This is the stage where the tiny capillaries of the retina become semi-permeable membranes. (Later, they will leak fluid and blood.)
The best way to catch background retinopathy before the disease progresses is to schedule regular eye exams with an ophthalmologist. All diabetics, even those who do not require vision correction, should have their eyes thoroughly examined every year. Diabetic women who are pregnant should have their eyes examined every trimester.
Blood glucose control is also a factor in proliferative diabetic retinopathy, macular edema and background retinopathy. Taking care of your eyes goes hand-in-hand with watching your blood sugar. Testing your blood sugar (and testing it often) is imperative for controlling diabetes and preventing vision loss.
During the earliest stages, diabetic retinopathy is often asymptomatic. This means that there are no noticeable symptoms - such as pain or vision loss - to the patient, but it is highly possible that an eye specialist might find signs of the disease. For example, retinal swelling may be present, which can only be detected through an eye examination. Get more information on non-proliferative diabetic retinopathy.
When the center of the macula - the tiny part of the eye responsible for sharp, direct vision - begins to swell, vision may become blurry. This middle stage of diabetic retinopathy, known as macular edema, often overlaps the other stages. This is the stage where the capillaries in the retina begin to leak fluid, causing swelling and blurred vision.
There are two types of macular edema: focal and diffuse. Focal macular edema occurs when the retinal capillaries develop micro-aneurisms which leak fluid, resulting in several distinct points of leakage. Diffuse macular edema is caused by the dilation of retinal capillaries, creating leakage that is diffused over a general area.
The type of macular edema present will determine the kind of diabetic retinopathy treatment your doctor uses. Early detection of macular edema will help ensure the most effective treatment, so diabetics should have their eyes examined every year by a qualified ophthalmologist.
Spotty or Blurry Vision
As the disease advances, minor visual impairment can occur. Although patients are still able to see, they can be frustrated by blurring and blind spots that inhibit clear vision. These symptoms of diabetic retinopathy are sometimes linked to macular edema, which is the swelling of the part of the eye that controls central vision, known as the macula.
Proliferative Diabetic Retinopathy
As damaged blood vessels begin to break, blood can leak into the eye. This third stage of diabetic retinopathy, called proliferative diabetic retinopathy, is characterized by cloudiness and impaired vision. When the retinal capillaries break, they are no longer able to supply the retina with the necessary nutrients. The nutrient-starved retina sends out a chemical signal that prompts the growth of new capillaries. This growth is called neovascularization.
The new blood vessels that form as a result of proliferative diabetic retinopathy cause more damage to the eye. These capillaries are unable to restore nutrients to the retina because they are fragile and weak. They also tend to burst, causing blood and fluid to leak into the eye. The new vessels also exert traction on the surrounding structures and connective tissue, which can eventually detach the retina. Intraocular pressure can also increase as a result of the new capillaries, as they can block the ducts where fluid is drained from the eye. This condition is known as neovascular glaucoma. During proliferative diabetic retinopathy, scar tissue development, retinal detachment, and blindness can occur.
In the final stage of NPDR and the onset of proliferative diabetic retinopathy, severe visual impairment takes place, often accompanied by retinal detachment. Retinal detachment in PDR patients is caused by both the intense swelling (due to abnormal capillaries leaking fluid into the eye) and the traction of scar tissue on the retina itself. If left untreated, retinal detachment causes serious vision loss and even blindness.
If the disease has progressed into proliferative diabetic retinopathy without the patient receiving any preventative care or medical intervention, blindness can result. At this time, PDR is the leading cause of new cases of blindness in the United States. Retinal detachment, macular edema, and the breakdown of capillaries in the retina can all prevent normal blood flow through the eye and lead to total vision loss.
Treatment and Recovery
In the earliest stages of diabetic retinopathy, serious treatment is not always required, as the disease can often be managed through noninvasive, lifestyle-oriented methods. However, if the disease becomes proliferative, more aggressive treatment aimed at preventing further vision loss and improving impaired vision is necessary. There are two types of diabetic retinopathy treatment available for patients, vitrectomy surgery and laser photocoagulation surgery.
The length and extent of recovery after a procedure to treat diabetic retinopathy depends upon the type of treatment the patient received. Recovery also depends upon the severity of the disease, as more aggressive measures are necessary to combat the most advanced stages from worsening.
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