Purpose To demonstrate the efficacy and safety of ranibizumab 0.5 mg pro re nata (PRN) versus laser photocoagulation for the treatment of Chinese patients with visual impairment due to diabetic macular edema (DME). Methods REFINE was a phase III, 12-month, double-masked, multicenter, laser-controlled study in patients (aged ≥ 18 years) with DME. Patients were randomized 4:1 to receive either ranibizumab 0.5 mg or laser dosing regimen. Efficacy was evaluated as mean average change in best-corrected visual acuity (BCVA) from Months 1 to 12 versus baseline (primary endpoint), anatomical outcomes, treatment exposure, and safety were also assessed. Results Ranibizumab was statistically superior ( p  < 0.001) to laser treatment, with a mean average BCVA gain of 6.8 letters (ranibizumab) over 12 months versus 1.1 letters (laser). At Month 12, mean BCVA gain was 7.8 letters (ranibizumab) and 2.5 letters (laser) from baseline. Patients in the ranibizumab arm received a mean number of 7.9 intravitreal injections, whereas those in the laser arm received a mean of 2.1 treatments. There were no new safety signals. Conclusion Ranibizumab 0.5 mg PRN demonstrated a statistically significant and clinically meaningful treatment effect versus laser and was well tolerated in Chinese patients with visual impairment due to DME over 12 months.