This study reports the two-year results of the Diabetic Retinopathy Clinical Research Network (DRCR.net) multi-center trial, which randomized 854 eyes to intravitreal 0.5 mg ranibizumab or 4 mg triamcinolone combined with focal/grid laser compared with focal/grid laser alone for treatment of diabetic macular edema (DME).
The two-year BCVA and safety results were consistent with the one-year results, showing the superiority of both ranibizumab treatment groups over sham through two years. Compared with sham, the ranibizumab + prompt laser group and the ranibizumab + deferred laser group achieved a mean improvement in BCVA of 3.7 and 5.8 letters, respectively, while visual acuity in the triamcinolone group decreased by 1.5 letters.
Additionally, the number of injections required to achieve stable visual acuity between the one and two year visits was relatively few. Patients in the ranibizumab plus prompt or deferred laser group had two or three injections, respectively.
All of the above suggests that the DRCR.net retreatment algorithm was successful in avoiding vision loss while reducing the number of injections needed through two years.
However, about 40 percent of the eyes in the two ranibizumab groups still had central macular edema (OCT central subfield ≥250 µm) at the two-year visit, although in only 20 percent to 24 percent was the retina more than mildly thickened (OCT central subfield ≥300 µm). The authors note that longer follow-up of this cohort will allow for assessment of other differences between immediate and deferred laser in the ranibizumab-treated groups.
No treatment-related systemic events were observed. Three of the 375 ranibizumab group participants had injection-related endophthalmitis, while elevated IOP and cataract surgery were more frequent in the triamcinolone plus prompt laser group.
The authors note that this study did not address the cost-effectiveness of this treatment or its impact on costs associated with vision impairment. It was also beyond the scope of this study to determine whether other treatment algorithms (e.g., retreatment every four weeks for two years) or other anti-VEGF drugs (e.g., bevacizumab or aflibercept) would result in different or similar outcomes. Lastly, the authors conclude that the sustained decreased chance of panretinal photocoagulation in the ranibizumab and triamcinolone groups merits further investigation to determine the role of anti-VEGF drugs in the prevention or treatment of proliferative diabetic retinopathy.