Evaluation of the Efficacy of Vitrectomy for Persistent Diabetic Macular Edema and Associated Factors Predicting Outcome

PURPOSE To evaluate the efficacy of vitrectomy for persistent diabetic macular edema after laser photocoagulation or intravitreal triamcinolone injections and to determine the demographic and ocular factors that influence functional and anatomical outcomes. METHODS We retrospectively evaluated 55 eyes (51 patients) that had persistent diffuse macular edema after laser photocoagulation or intravitreal triamcinolone injections. We compared preoperative and postoperative best corrected visual acuity and macular thickness by Optical Coherence Tomography and investigated factors including patient's age, presence of vitreomacular traction, grade of diabetic retinopathy, and intraoperative internal limiting membrane removal that may influence the surgical results. RESULTS The mean preoperative BCVA (log MAR) was 0.91+/-0.40 (0.8-1.2). The BCVA improved to 0.72+/-0.39 (0.3-1.2). The mean preoperative macular thickness was 440+/-130 (202-805) micrometer and the mean macular thickness decreased to 306+/-97 (136-580) micrometer postoperatively. The eyes showed statistically significant improvement in BCVA and central macular thickness (p<0.001). Preoperative better BCVA was associated with an improved postoperative visual acuity. (p=0.04). No other covariates were found to be statistically significant factors for prognosis of postoperative BCVA. CONCLUSIONS In eyes with persistent diabetic macular edema after laser or IVTA injections, vitrectomy was effective for decreasing macular thickness and improvement of vision. The visual improvement after vitrectomy was associated with the preoperative better BCVA.