Pars plana vitrectomy with internal limiting membrane peeling for diffuse diabetic macular edema

Abstract

Purpose: To evaluate the efficacy of pars plana vitrectomy (PPV) with internal limiting membrane (ILM) peeling for treatment of diffuse diabetic macular edema (DME).

Methods: We retrospectively reviewed the medical records of 51 patients (63 eyes) who underwent PPV with ILM peeling for diffuse DME. All eyes showed increased central macular thickness (CMT) of ≥275μm. Best-corrected visual acuity (VA) measured using the Landolt chart was found to be 0.06-0.5. The CMT and VA were recorded before and 1, 3, 6, and 12 months after treatment. The VA obtained using the Landolt chart was converted to the logarithm of the minimum angle of resolution (logMAR). VA was considered to be significantly improved or decreased when the change in VA (logMAR) value was >0.3. The factors that influenced VA improvement and CMT reduction were analyzed.

Results: PPV with ILM peeling decreased DME with a recovery of VA. CMT significantly reduced from 545.8±137.4μm at baseline to 330.7±126.9μm at 12 months (paired t-test, p<0.001). The VA in logMAR significantly improved from 0.62±0.28 at baseline to 0.46±0.36 at 12 months (paired t-test, p < 0.001). In 22 eyes (34.9%), the VA significantly improved at 12 months, while 6 eyes (9.5%) showed a decrease in VA at 12 months. In 20 eyes (31.7%), a posterior subtenon injection of triamcinolone acetonide (STTA) (20 mg) was administered at the end of the surgery. In eyes with additional STTA, a greater reduction in CMT was observed 3 and 6 months after the treatment (Mann-Whitney test, p=0.01 and 0.05, respectively) compared to eyes without STTA. VA was significantly improved in the eyes with STTA than in those without STTA at 3 and 6 months (Mann-Whitney test, p=0.02 and 0.03, respectively). However, the STTA effect decreased at 12 months. An intravitreal bevacizumab (IVB) injection (1.25mg) was administered at the end of the surgery in 14 eyes (22.2%). However, the IVB showed no additional efficacy with respect to CMT or VA. No serious complications, such as endophthalmitis or systemic events, developed in any of the eyes studied.

Conclusions: For diffuse DME, PPV with ILM peeling was effective in reducing macular edema and improving VA over a period of 1 year. Administration of STTA, and not IVB, facilitated a rapid reduction in macular edema and enabled visual recovery.