Ranibizumab proves effective to treat proliferative diabetic retinopathy

December 2, 2015
Injections perform as well as laser treatment, but there are risks to both therapies.

Ranibizumab injections may be an effective alternative treatment for proliferative diabetic retinopathy (PDR) when compared with laser treatment, according to a new study in JAMA.

When left untreated, diabetic retinopathy can lead to blindness.

To prevent damage, patients with the most advanced form—proliferative diabetic retinopathy—often undergo panretinal photocoagulation (PRP), in which a laser burns and seals or destroys leaking blood vessels and prevents new blood vessels from forming. PRP is effective at lowering the risk of severe vision loss, but it also can severely damage a patient's peripheral vision and night vision and can worsen diabetic macular edema (DME).

"The [laser] protocol prevents blindness but often diminishes quality of life," says A. Paul Chous, O.D., optometric representative to the National Diabetes Education Program of the National Institutes of Health who practices in Tacoma, Washington.

Ranibizumab, already used to treat other retinal vascular diseases, does not lead to these visual function side effects and may even improve visual acuity slightly. In this study, 305 adults with PDR at 55 U.S. sites were randomly assigned to receive PRP or 0.5 mg of ranibizumab. PRP treatment was completed in one to three visits, while ranibizumab was given as frequently as every four weeks depending on the patient's response and pre-specified treatment protocol.

What the study shows

Over the study's two-year period, the mean visual acuity letter score improvement from baseline was +2.8 in the ranibizumab group and +0.2 in the PRP group, proving that ranibizumab was noninferior to PRP. The laser group also experienced significantly more loss of visual field sensitivity, more DME and required more vitrectomy surgeries.

"The question is: What's going to happen long term?" Dr. Chous says. "How many injections will [the ranibizumab group] need in order to keep their PDR at bay? And what will be the systemic effects with higher cumulative exposures?"

Ranibizumab is an anti-vascular endothelial growth factor (VEGF) agent, which potentially increases risk of stroke, heart attack or pulmonary embolism. If PDR patients need to continue ranibizumab treatment long term, there is concern that cumulative dosages could increase risk of these events, Dr. Chous says. The other drawback is that anti-VEGF therapy costs more than PRP.

The researchers plan to follow these patients for five years. This will help determine how many patients need follow-up injections, how much ranibizumab patients need for long-term success, the risk of thromboembolism and how many will need laser treatment after all, Dr. Chous says.

The AOA follows all research and new technology closely, including new treatments for PDR and other diabetes-related eye disease. Although ranibizumab appears to be an effective alternative treatment for patients who have PDR, more research is needed for it to supplant laser treatment.

Continue the conversation about diabetes

Although diabetes observance month has come to an end, doctors should continue the conversation about diabetes with patients year round, using the following resources:

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