People with proliferative diabetic retinopathy can reduce their risk of blindness by 90% with appropriate treatment and follow-up. Few serious conditions have such controllable outcomes.
During the nonproliferative stage of diabetic retinopathy, treatment consists of controlling glucose levels, keeping blood pressure within a desired range, and limiting blood cholesterol. In the late nonproliferative stage, focal laser treatments may be used to seal leaking blood vessels. Once new blood vessels begin to appear in the proliferative stage, scatter laser treatment can be used to shrink them.
Laser therapy is usually an outpatient procedure requiring only a topical anesthetic. It aims to stabilize vision but generally does not restore sight that has already diminished.
Focal or panretinal laser treatment for macular edema
Macular edema may occur in late-stage nonproliferative diabetic retinopathy. If it has not caused scarring, macular edema can be treated with a focal laser that seals off leaking blood vessels. This approach lowers the risk of vision loss by 20% in people with mild or moderate nonproliferative diabetic retinopathy. As the disease becomes more severe and extensive, a scatter laser can be used.
Scatter (panretinal) laser treatment
Scatter laser photocoagulation (sealing off leaking vessels with a laser beam) has been shown to reduce the risk of blindness by as much as 90%. Few treatments for any disease can boast of such success. This therapy slows the progression to proliferative retinopathy and cuts in half the chance that vitrectomy (see below) will be needed in certain patients. Because the procedure destroys part of the retina, you risk some loss of central vision, night vision, and peripheral vision.
The retina is a thin layer of tissue at the back of the eye. It’s sandwiched between the choroid and the vitreous humor, a jelly-like substance that fills the cavity of the eyeball (see How the Eye Works). Abnormal vessels caused by diabetic retinopathy can hemorrhage into the vitreous humor. Blood in the vitreous, as it’s called for short, can diminish vision by keeping light from reaching the retina, and it can also impede laser surgery.
When hemorrhaging occurs, the vitreous can be suctioned right out of its chamber in the eyeball. Usually under local anesthesia, your eye surgeon will make a small incision into the sclera (the "white" of the eye) to access the vitreous, which is replaced with a neutral saline (salt) solution to maintain the shape of the eyeball. Over time, your body will replace the saline with new vitreous.
Investigational Treatments and Trends
Scientists are still studying the exact mechanisms by which diabetes harms the eye. Insulin receptors in the rod cells of the retina are of particular interest. Genetic models have recently been developed that allow researchers to test the efficacy of various therapies.
Researchers have discovered that neovascularization (the abnormal development of new blood vessels) is regulated by a protein called vascular endothelial growth factor A(VEGF). (See Overview of Diabetic Retinopathy for an explanation of the neovascularization process.) Scientists hope they can learn how to manipulate it with drugs or other treatments in order to prevent abnormal vessel formation. The antifungal drug itraconazole has shown surprising success as a VEGF inhibitor. Other drugs may act on the molecules that signal vessel formation to begin. The anti-VEGF drug Lucentis is being studied in people with diabetic retinopathy.
Corticosteroid medications may be of use in treating macular edema, which often accompanies diabetic retinopathy. In one small, preliminary study, the corticosteroid triamcinolone was found to modestly improve vision in people with macular edema.
The Price of Delay
Treating diabetic retinopathy not only preserves the sight of thousands of people every year, it also saves the United States an estimated $1.6 billion annually in health care and productivity costs. But ultimately it's the human cost that really matters. When effective treatment is delayed, each person whose sight is diminished unnecessarily suffers an immeasurable loss. And for each person whose sight is preserved, treatment is simply priceless.
- What is Diabetic Retinopathy?
- Symptoms of Diabetic Retinopathy
- Reducing the Risk of Diabetic Retinopathy
- Diagnosing Diabetic Retinopathy