Intravitreal double-dose ranibizumab therapy for refractory diabetic macular edema

Abstract

Purpose: To evaluate the efficacy of ranibizumab (1 mg) for the treatment of refractory diabetic macular edema (DME). Materials and Methods: This prospective, consecutive, non-comparative case series included 24 eyes with refractory DME. Patients were included in the study independently of the size of the leakage area, retinal thickness, visual acuity (VA), age, metabolic control and type of diabetes mellitus. Exclusion criteria included presence of a hard exudate at the fovea, macular edema secondary to causes other than diabetic maculopathy, signs of vitreomacular traction clinically or by optical coherence tomography (OCT), proliferative diabetic retinopathy requiring treatment, history of glaucoma or ocular hypertension and macular ischemia. Patients who had intraocular/periocular steroid/antivascular endothelial growth factor injections within 6 months of the enrollment or significant media opacities were excluded. After a written informed consent was obtained, all patients were treated with three intravitreal injections, 1 month apart, of 0.1 mL (1 mg) injection of ranibizumab. Changes of retinal thickness and VA, as measured by the Snellen chart and converted to decimal equivalents, were evaluated. Results: A total of 24 eyes of 24 patients (nine females and 15 males) with non-proliferative diabetic retinopathy (12 patients; 50%) or quiescent diabetic retinopathy (12 patients; 50%) were included in the study. Their mean age and standard deviation (SD) was 45.5 ± 13.1 years (range: 27-71 years). All patients completed 6 months of follow-up. No injection-related side-effects, either locally or systemically, were observed during the follow-up period. All included patients were subjected to at least one method of treatment for DME. At baseline, the mean VA ±SD was 0.015 ± 0.008; after 1 month from the first injection, the mean VA increased to 0.019 ± 0.008 (significant increase, P = 0.0013). The VA remained the same after the second and the third injections. Six months after the third injection, the mean VA ± SD was 0.018 ± 0.009 (significant increase, P = 0.0013). The mean central retinal thickness ± SD by OCT was 526.7 ± 243.4μ at baseline. Four weeks post-operatively, a significant decrease of mean retinal thickness ± SD to 429.7 ± 187.8μ was observed. Eight weeks after the injection, the mean macular retinal thickness ± SD had further decreased to 352.2 ± 142.5μ, which is a significant difference (P = 0.001) compared with the baseline thickness. After 12 weeks, the mean retinal thickness ± SD further decreased to 333.7 ± 114.5μ (P = 0.001). Conclusion: The intravitreal injection of 1 mg of ranibizumab provides a new treatment strategy for refractory DME, which offers patients a true perspective of visual recovery. Further prospective and randomized studies will be needed to better determine which patients benefit the most and how often and in which concentration the drug should be administered.