Targeting diabetic blindness
Leo Gonzales sits down for what appears to be an ordinary eye exam. Dr. Arup Das asks him to look up, then down and asks how his eye is doing. Then, as Gonzales reclines on a bed, Das leans over with a syringe and carefully delivers an injection directly into his right eye.
Diagnosed with diabetes in 1995, Gonzales moved to Albuquerque from Roswell a year ago to be close to Das for these monthly treatments. He couldn’t have placed himself in better hands. UNM Chief ophthalmologist Das and basic scientist Dr. Paul McGuire are partnering to find a cure for blindness caused by diabetic retinopathy, which threatens the 19.7 million Americans (and 150,000 New Mexicans) living with diabetes.
Ten to 15 years after a diabetes diagnosis, patients develop retinopathy, which causes blood vessels in the eye to leak into the central portion of the light-sensitive retina in the back of the eye, called the macula. This causes macular edema (swelling) and gradual vision loss.
Current treatment options include injections or laser therapy. Gonzales has received both within the past year. “The results are tremendous,” he says. “My right eye couldn’t see anything, and now I can see about 10 feet in front of me."
The injectable drug targets VEGF, one of several molecules in the retina that contributes to this leakage. “VEGF has been extensively studied, but isn’t the optimal target for treatment,” Das explains. “The effect of these drugs is transient. Some patients you have to inject for months, years even. If you stop injections, leakage may come back. Many don’t respond to treatment at all and the edema remains persistent.”
McGuire says he and Das have found great advantages in their partnership of 15 years. “Das brings the clinical view,” he says. “I bring in basic science. Together, we move forward quicker.” The pair discovered other molecules that play a prominent role in diabetic retinopathy, one of which is CCL-2. They found that CCL-2 attracts white blood cells (monocytes) that infiltrate the retina.
“Can we target this monocyte ‘trafficking’ into the retina in early stages of diabetes?” Das asks. “If we can prevent this influx of white blood cells, maybe we can prevent the cascade of inflammation and vessel leakage completely.”
Unfortunately, a substantial number of patients do not receive appropriate eye care, especially in rural areas. One way to tackle this problem is through telemedicine, which Das and colleagues have begun using to expand retinopathy screening and treatment for patients throughout the state.
Meanwhile, Das sees a pressing neeed for new drug interventions. “I get frustrated,” he says. “I keep injecting patients. Some respond and some don’t. I’m looking forward to a day when there is a drug that’s effective that everyone will respond to, and I can see patients get better again.”
While Das and McGuire seek new treatments, Das offers some wise advice: “The most important way to prevent blindness is through diet and controlling blood sugar, blood pressure and blood cholesterol. If a patient doesn’t control their diabetes, treatments will be ineffective.”
Gonzales agrees. “If you’re diagnosed with diabetes, get on a strict diet immediately,” he says. “I never did that. I thought meds would take care of my diabetes, but here I am. Now I’m taking care of myself and eating well, and my eyes improved.”