This study compares the efficacy and safety of intravitreous ranibizumab versus panretinal photocoagulation (PRP) over 5 years of treatment in patients with proliferative diabetic retinopathy (PDR).
Study design
As part of the Diabetic Retinopathy Clinical Research Network (DRCR.net) multicenter randomized clinical trial, researchers examined 394 eyes with PDR. Of these, 191 eyes were assigned to intravitreal ranibizumab while 203 eyes underwent PRP.
Outcomes
Only 66% of participants (184 of 277, excluding deaths) completed 5-years of follow up. The average visual acuity was approximately 20/25 in both groups, with a mean change in visual acuity letter score of 3.1 and 3.0 letters in the ranibizumab and PRP arms, respectively. The mean change in visual field total point scores was -330 (n=41) in the ranibizumab group and -527 (n=38) in the PRP group. Interestingly, visual field loss progressed in both groups from years 2 through 5 with the difference between the groups diminishing.
Vision-impairing DME developed in 27 eyes in the ranibizumab group and 53 eyes in the PRP group. Eyes in the ranibizumab group received a mean of 7 injections in the first year, and decreased to an average of 3 injections each year thereafter.
Limitations
This trial was well designed but lost many patients to follow up. This is concerning and may limit extrapolation of these findings to real-world situations. Nonetheless, patients who completed follow-up through 5 years had very good visual outcomes with no major differences detected between the groups.
Serious complications from PDR were uncommon in both groups, though the ranibizumab group had lower rates of visually significant DME and less visual field loss. While the authors conclude that anti-VEGF and PRP are both viable treatment options for PDR, we do not know the outcomes of patients who did not return, especially the outcomes of those who received ranibizumab without PRP.
Clinical significance
The study lends support to the idea that anti-VEGF monotherapy may be just as effective as PRP when treating PDR over a 5-year period, though these outcomes are contingent on adherence to regular follow-up. It will be critical for clinicians to account for real-world compliance rates and costs when determining the best treatment for individual patients.