ourtesy NIH
Proliferative retinopathy occurs when abnormal new blood vessels and scar tissue form on the surface of the retina.
Diabetic retinopathy—a condition that causes the eye's light-sensitive retina to swell and hemorrhage—is the leading cause of blindness among 25-74 year-olds in the industrialized world. Anyone with type 1 or type 2 diabetes is at risk for this eye disease and 45 percent of persons with diabetes already have some form of it.
With the incidence of diabetes predicted to double over the next 30 years, researchers are more committed than ever to finding new approaches to prevention and treatment of diabetic eye disease. At the Penn State Milton S. Hershey Medical Center
and the College of Medicine, that commitment has generated a promising new therapy. Thomas Gardner, professor of ophthalmology and cellular and molecular physiology and vice chair for ophthalmology research at the College of Medicine, is enthusiastic about the new approach.
"Diabetic retinopathy is often not treated until the late stages of the disease and there is a limit to what the laser surgery can achieve at that point," says Gardner. "We know that insulin helps retinal neurons survive," he continues, "but giving intensive insulin therapy to the patient
systemically creates a high risk of hypoglycemia."
To reduce the risk of hypoglycemia yet still deliver the benefits of intensive therapy, a long lasting, localized drug-delivery system was required, explains Gardner. "We knew we needed something that was easy to administer and offered sustained-release therapy, because things like injections and
daily eye drops discourage patient compliance."
Gardner and colleagues turned to Tao Lu Lowe, assistant professor of surgery, bioengineering, and materials science and engineering at the College of Medicine, for help. Lowe's focus is the development of innovative drug-delivery systems. She responded to the needs of the retinopathy researchers by creating a non-toxic polymer hydrogel—"a little gel capsule" says Gardner—that could be implanted under the surface of the eye with a simple in-office procedure, and offer continuous low-dose insulin directly to the retina for six to twelve months.
"We've been doing rat studies on this approach for over a year to validate our concept," Gardner says. "I'd be happy to see human trials within the next five years."
Thomas Gardner, M.D., is professor of ophthalmology and cellular and molecularphysiology in the College of Medicine; tgardner@psu.edu. Tao Lu Lowe, Ph.D., is assistant professor of surgery, bioengineering, and materials science and
engineering in the College of Medicine; tlowe@psu.edu.