Retinal Consultants of Arizona – Diabetic Eye Disease
High blood sugar levels can damage blood vessels in the retina, termed diabetic retinopathy. There are two types of diabetic retinopathy: nonproliferative diabetic retinopathy (NPDR) and proliferative diabetic retinopathy (PDR). NPDR is an early stage of diabetic retinopathy in which tiny blood vessels within the retina leak blood, fluid, or cholesterol. This leakage can cause blurry vision if it affects the macula, a small area in the center of the retina that allows us to see fine details clearly.
Nonproliferative diabetic retinopathy (NPDR)
Many people with NPDR do not have any symptoms. When vision is affected it is a result of macular edema, macular ischemia, or both. Macular edema is swelling or thickening of the macula. The swelling is caused by leaking retinal blood vessels. It is the most common cause of visual loss in diabetes. Vision loss may be mild to severe, but peripheral vision is unaffected. Macular ischemia occurs when small blood vessels close. Vision blurs because the macula no longer receives sufficient blood supply to work properly.
Proliferative diabetic retinopathy (PDR)
PDR develops when abnormal new vessels (neovascularization) begin growing on the surface of the retina or optic nerve. The main cause is due to a lack of blood flow from many closed retinal blood vessels. New blood vessels are formed in an attempt to supply blood to the area where the original vessels closed. Unfortunately, the new abnormal blood vessels are very fragile, leading to further leakage of blood and blurred vision. Furthermore, the new blood vessels are often accompanied by scar tissue that may cause wrinkling or detachment of the retina. PDR may cause more severe vision loss than NPDR because it can affect both central and peripheral vision.
New blood vessels from PDR are fragile and may bleed into the vitreous gel that fills the eye. If there is only a small amount of bleeding, a person might see only a few new floaters. A large amount of bleeding can block out all of the vision. Sometimes, depending on the extent of the hemorrhage, the blood may be absorbed over a few days to months. Other times, vitrectomy surgery may be recommended to clear the vitreous blood.
The new, abnormal blood vessels from PDR often lead to scar tissue formation which can cause wrinkling and pulling of the retina from its normal position. Macular wrinkling or detachment can cause visual distortion or severe vision loss. The scar tissue can usually be removed with vitrectomy surgery.
If the new, abnormal vessels grow on the iris (colored part of the eye) and drainage channels in the front of the eye, they can block the normal flow of fluid out of the eye. Pressure in the eye builds up, resulting in painful neovascular glaucoma and severe vision loss or blindness without urgent treatment.
Strict control of your blood sugar and blood pressure will significantly reduce the long-term risk of vision loss from diabetic retinopathy. In some cases, your doctor may recommend injections of medicine in your eye to treat macular edema. These special injections may be steroids or other medications that are designed to reduce the swelling of the macula.
Laser surgery is often recommended for people with macular edema, PDR, and neovascular glaucoma. The main goal of treatment is to prevent further loss of vision or a worsening of your condition. Multiple laser treatments over time are sometimes necessary. Laser surgery does not cure diabetic retinopathy and does not always prevent further loss of vision.
In advanced PDR, your doctor may recommend vitrectomy surgery. This is a surgical procedure, performed in an operating room, in which the vitreous is removed and replaced with a clear fluid. If the retina is detached, it can often be repaired with removal of scar tissue during the vitrectomy surgery. Surgery should usually be done early because macular distortion or retinal detachment will cause permanent visual loss. The longer the macula is distorted or out of place, the more serious the vision loss will be.