This study involved 52 clinical sites within the Diabetic Retinopathy Clinical Research Network (DRCR.net), supported by the National Eye Institute (NEI) and the National Institute of Diabetes and Digestive and Kidney Diseases, part of the National Institutes of Health. It shows that nearly 50 percent of patients who received ranibizumab plus laser treatment experienced substantial visual improvement after one year, compared with 28 percent who received the standard laser treatment.
"These results indicate a treatment breakthrough for saving the vision of people with diabetic macular edema," said Neil M. Bressler, M.D., chair of the DRCR.net and chief of the Retina Division at the Wilmer Eye Institute, Johns Hopkins University, Md. "Eye injections of ranibizumab with prompt or deferred laser treatment should now be considered for patients with characteristics similar to those in this clinical trial."
Participants, who were on average in their early 60s, were diagnosed with type 1 or 2 diabetes and macular edema. Researchers randomized 691 participants (854 eyes) with diabetic macular edema (DME) involving the central macula to one of four groups: sham injections plus prompt focal/grid laser treatment within one week, ranibizumab injections plus prompt laser treatment, ranibizumab plus deferred laser treatment after six months or more or triamcinolone and prompt laser.
Ranibizumab injections could be given as often as every four weeks, and triamcinolone injections or laser treatments could be given as often as every 16 weeks. In general, treatment was continued until a participant's vision or retinal thickness returned to normal, or additional treatment did not improve vision or retinal swelling.
After one year, nearly 50 percent of eyes treated with ranibizumab and prompt or deferred laser treatment showed a substantial visual improvement (≥10 letter gain from baseline), compared with 28 percent of eyes that received laser treatment alone or triamcinolone plus laser.
Although participants in all three injection groups had a greater decrease in retinal thickness after one year than with laser treatment alone, patients who received triamcinolone injections had greater complication rates. About 30 percent of people in the triamcinolone group developed high eye pressure that required medications, and about 60 percent developed cataracts that required surgery.
The study found that eye injections of ranibizumab were not associated with any serious risks such as heart attack or stroke. DRCR.net researchers will continue to monitor the study participants for at least three years to obtain additional information about the safety and effectiveness of these macular edema treatments.
The authors note that if ranibizumab is given as it was applied in this study, early data suggests close patient follow-up because the results indicate that additional ranibizumab or focal/grid laser, or both, are needed in most eyes through at least two years, even if 'success' criteria are met early in the course of treatment.
They write: "According to the DRCR.net retreatment algorithm used in this study, eyes assigned to ranibizumab that met 'success' criteria at the 16-week study visit were not required to have continued injections unless visual acuity worsened or macular edema returned. Approximately two thirds of these early successes received additional ranibizumab at ≥1 visit after the 16-week visit. Furthermore, not all eyes avoided the need for focal/grid laser when following the protocol assigned to the ranibizumab + deferred laser group. Specifically, for eyes assigned to ranibizumab + deferred laser, approximately one third required focal/grid laser at least once between the 24-week and the 1-year study visits when the retreatment algorithm was followed."
Find more information about this clinical trial (NCT00444600) at www.clinicaltrials.gov.