Diabetic Retinopathy
People with diabetes are not able to break down and store sugar properly. This leads to increased levels of blood sugar. When blood sugar levels increase, it becomes difficult for oxygen to be delivered to the cells of the retina. The blood vessels in the retina weaken, and this condition is known as diabetic retinopathy. If a patient is diagnosed with diabetic retinopathy, fluorescein angiography is often used to identify the extent of the disease. (see angiogram)
Nonproliferative Diabetic Retinopathy (NPDR)
There are two stages of diabetic retinopathy. In the first stage, nonproliferative diabetic retinopathy (NPDR), the blood vessels in the retina leak or break. This usually does not cause symptoms or vision loss. In some cases, however, vision is affected. The blood vessels can leak blood or fluid into the macula. When there is a leak into the macula, swelling occurs; this is called a macular edema. Macular edemas often result in loss or decrease of central vision, but peripheral vision is not affected. A retina specialist can treat macular edema with a focal laser. (see focal laser)The blood vessels surrounding the macula may also close, causing decreased blood flow to the macula, and therefore vision becomes blurred. This is called macular ischemia.
Proliferative Diabetic Retinopathy (PDR)
The second stage of diabetic retinopathy is more serious and is called proliferative diabetic retinopathy, or PDR. In this stage many blood vessels become closed, and the blood flow is decreased. The retina then attempts to reestablish the blood flow by making new blood vessels. These new vessels are abnormal and fragile, and can cause scar tissue to develop. This can lead to several problems:
- A retinal detachment may occur as scar tissue from the new blood vessels wrinkles, pulling the retina away from the back of the eye.
- A vitreous hemorrhage occurs when the new vessels leak into the vitreous. It can cause floaters to occur, or may completely block vision, depending on the amount of blood present in the vitreous. If the patient has a vitreous hemorrhage, a vitrectomy may be performed. (see vitrectomy)
- Neovascular glaucoma can occur when these new fragile blood vessels grow on the iris. This decreases the flow of fluid from the eye and elevates intraocular pressure. This can cause damage to the optic nerve.
Prevention
Regular eye exams are very important for people with diabetes. A retina specialist using an ophthalmoscope to look inside the eye is often able to diagnose early NPDR even before symptoms arise. Those with NPDR often do not experience any symptoms. During the later stages of retinopathy, patients often have blurred or cloudy vision and may see floaters. Double vision and loss of central vision are also symptoms of diabetic retinopathy.
Control of blood sugar is very important in preventing vision loss caused by diabetic retinopathy. The longer that you have had diabetes, the more likely you are to develop diabetic retinopathy. All diabetics should have yearly eye exams to aid in early diagnosis of retinopathy. If you have been diagnosed with diabetic retinopathy, you may need to see a retina specialist more often to monitor the progression of the disease and to prevent vision loss. Diabetic women who become pregnant should schedule an eye exam during their first trimester, as diabetic retinopathy progresses more quickly in pregnancy.
If you are experiencing a decrease in central vision, double vision, or floaters or other changes that last more than a few days, you should make an appointment for an eye exam as soon as possible.