Surgical and anatomical outcomes of pars plana vitrectomy for diffuse nontractional diabetic macular edema

Purpose: To prospectively determine the efficacy of vitrectomy combined with intravitreal triamcinolone acetonide (IVTA) injection, internal limiting membrane (ILM) peeling, or both in treating diffuse nontractional diabetic macular edema (ME). Methods: Patients with diffuse ME of <6 months who had no evidence of macular traction or macular ischemia were included in the study. Patients previously diagnosed with glaucoma underwent vitrectomy with ILM peeling. All other patients were randomly assigned to vitrectomy or vitrectomy with ILM peeling followed by IVTA injection. Results: Forty-two eyes of 38 patients were included in the study. Mean follow-up was 12 months. A statistically significant reduction in macular thickness was found at 1 month to 6 months, disappearing at 12 months. No differences in visual acuity between treatment groups were found during follow-up. Visual acuity improved in 5 (12%) of 42 eyes, remained unchanged in 32 (76%) of 42 eyes, and worsened in 5 (12%) of 42 eyes. Complications included increase in intraocular pressure in 8 (26%) of 31 eyes, mild vitreous hemorrhage in 6 (14%) of 42 eyes, central retinal pigment epithelium changes in 5 (12%) of 42 eyes, and cataract progression in 11 (38%) of 29 phakic eyes. Conclusion: In diffuse diabetic ME with no retinal traction, vitrectomy with either ILM peeling or IVTA injection at the end of surgery produces a short-term improvement in retinal thickness but no long-term anatomical or functional improvements.