PURPOSE: To evaluate the therapeutic efficacy of a novel surgical procedure for diffuse diabetic macular edema (DME), performed in conjunction with conventional vitrectomy. METHODS: This prospective, interventional case series involved 20 eyes of 18 consecutive DME patients with best-corrected visual acuities (BCVAs) between 0.301 and 1.221 logarithm of the minimal angle of resolution (logMAR) units and central retinal thicknesses (CRTs) greater than 275 μm. After vitrectomy, a small retinal detachment was made in the macula by injecting 50-100 μl balanced salt solution into the subretinal space using a 38-gauge needle. Before finishing the surgery, fluid-air exchange was performed. Patients were asked to remain in prone position for 1 day postoperatively. The main outcome measures were CRT and BCVA. RESULTS: The mean CRT of 554.6 ± 152.7 μm before surgery significantly decreased to 295.6 ± 92.5 μm (p < 0.0001) 1 week after surgery and to 185.8 ± 67.4 μm (p < 0.0001) at 6 months after surgery. The CRT was less than 250 μm in 18 eyes (90 %) at 6 months after surgery. The mean BCVA before surgery (0.706 ± 0.348) significantly improved at 6 months after surgery (0.431 ± 0.392, p < 0.0001). Postoperative BCVAs improved by more than 0.3 logMAR units in 13 eyes (65 %), remained unchanged in six eyes (30 %) and worsened in one eye (5 %). Macular edema recurred in three eyes (15 %) 2 months after surgery. CONCLUSIONS: This novel planned foveal detachment technique facilitated a rapid resolution of DME and contributed to improved visual acuity.