Targeted Retinal Photocoagulation for Diabetic Macular Edema with Peripheral Retinal Nonperfusion

Purpose To evaluate the effect of targeted retinal photocoagulation (TRP) on visual and anatomic outcomes and treatment burden in eyes with diabetic macular edema (DME). Design Phase I/II prospective, randomized, controlled clinical trial. Participants Forty eyes of 29 patients with center-involved macular edema secondary to diabetes mellitus. Methods Eyes with center-involved DME and Early Treatment Diabetic Retinopathy Study (ETDRS) best-corrected visual acuity (BCVA) between 20/32 and 20/320 (Snellen equivalent) were randomized 1:1 to monotherapy with 0.3 mg ranibizumab (Lucentis, Genentech, South San Francisco, CA) or combination therapy with 0.3 mg ranibizumab and TRP guided by widefield fluorescein angiography. All eyes received 4 monthly ranibizumab injections followed by monthly examinations and pro re nata (PRN) re-treatment through 36 months. Targeted retinal photocoagulation was administered outside the macula to areas of retinal capillary nonperfusion plus a 1–disc area margin in the combination therapy arm at week 1, with re-treatment at months 6, 18, and 25, if indicated. Main Outcome Measures Mean change in ETDRS BCVA from baseline and number of intravitreal injections administered. Results At baseline, mean age was 55 years, mean BCVA was 20/63 (Snellen equivalent), and mean central retinal subfield thickness (CRT) was 530 μm. Thirty-four eyes (85%) completed month 36, at which point mean BCVA improved 13.9 and 8.2 letters ( P = 0.20) and mean CRT improved 302 and 152 μm ( P = 0.03) in the monotherapy and combination therapy arms, respectively. The mean number of injections administered through month 36 was 24.4 (range, 10–34) and 27.1 (range, 12–36), with 73% (362/496) and 80% (433/538) of PRN injections administered ( P = 0.004) in the monotherapy and combination therapy arms, respectively. Goldmann visual field isopter III-4e area decreased by 2% and 18% in the monotherapy and combination therapy arms, respectively ( P = 0.30). Conclusions In this 3-year randomized trial of 40 eyes with DME, there was no evidence that combination therapy with ranibizumab and TRP improved visual outcomes or reduced treatment burden compared with ranibizumab alone.