The effect of conbercept combined with 577 nm subthreshold micropulse laser photocoagulation on diabetic macular edema

Abstract

Objective To observe the effect of conbercept combined with 577 nm subthreshold micropulse laser photocoagulation on diabetic macular edema (DME). Methods A prospective randomized controlled clinical study. From June 2016 to June 2017, 68 eyes of 68 patients with DME diagnosed in Central Theater Command General Hospital were enrolled in the study. The patients were randomly assigned to two different treatment groups: 36 eyes (36 patients) in the conbercept combined with 577 nm subthreshold micropulse lase group (combined treatment group) and 32 eyes (32 patients) in conbercept group (drug treatment group). All patients received three initial intravitreous injection of conbercept and re-treatment was performed according to the criteria which has been disigned before. BCVA was measured by ETDRS charts. The central macular thickness (CMT), total macular volume (TMV) were measured by Topcon 3D-OCT 2000. The BCVA, CMT and TMV in the combined treatment group and the drug treatment group were 57.9±12.4 letters, 427.8±129.4 μm, 10.14±1.50 mm3 and 59.0±16.0 letters, 441.0 ± 135.7 μm, 10.43±2.10 mm3, respectively. There was no significant difference (t=0.321, 0.410, 0.641; P=0.749, 0.683, 0.524). The follow-up period was more than 12 months. The changes of BCVA, CMT and TMV were compared between the two groups. Comparison of BCVA, CMT, TMV before and after treatment in and between groups using repeated measures analysis of variance. Results The average annual injection times was 5.8±1.9 in the combined treatment group and 8.5±2.4 in the drug treatment group. The difference was statistically significant (t=5.12, P=0.000). The BCVA in the 3rd, 6th, 9th and 12th month were 64.9±11.1, 65.6±10.5, 67.0±10.8, 66.6±10.7 letters and 65.7±15.8, 66.9±15.7, 66.4±13.0, 67.3±16.4 letters, respectively, and there were significant differences compared with BCVA before treatment (F=34.234, 10.137; P=0.000, 0.000). The CMT were 335.2±105.9, 352.6±106.6, 336.2±120.8, 305.9±97.0 μm and 323.9±92.8, 325.5±90.2, 327.6±108.2, 312.2±106.8 μm, respectively. The TMV were 9.20±1.08, 9.26±1.20, 9.20±1.63, 9.05±1.18 mm3 and 9.19±1.21, 9.35±1.69, 9.09±1.20, 8.92±1.10 mm3, respectively. Compared with the CMT (F=12.152, 12.917; P=0.000, 0.000) and TMV (F=11.198, 11.008; P=0.000, 0.000) before treatment, the differences were statistically significant. Conclusion Conbercept combined with 577 nm subthreshold micropulse laser and conbercept can effectively reduce CMT, TMV and improve BCVA in patients with DME, but combination therapy can reduce the injection times of conbercept. Key words: Diabetic retinopathy/complications; Macular edema/drug therapy; Angiogenesis inhibitors/therapeutic use; Antibodies, monoclonal/therapeutic use; Laser coagulation