• Written By: SriniVas R. Sadda, MD

    Is internal limiting membrane (ILM) peeling necessary in patients with diabetic macular edema but without obvious vitreo-macular traction? Data from this prospective, randomized trial suggests the answer is yes.

    Subjects included 40 patients with type 2 diabetes mellitus and chronic cystoid macular edema without evident vitreomacular traction. All patients underwent pars plan vitrectomy (PPV) and removal of the posterior hyaloid. Inclusion criteria allowed prior focal or panretinal laser coagulation. Patients were divided into three groups: (group I) surgical PVD, (group II) surgical PVD and ILM removal, (group III) preexisting PVD, vitrectomy and ILM removal.

    Mean BCVA remained unchanged in 85 percent of group II patients throughout six months follow-up, and decreased in 53 percent of group I patients. However, OCT revealed a significantly greater reduction of foveal thickness following PVD with ILM removal [group I: mean change: 95% CI (-208.95 μm;-78.05 μm), group II: (-80.90 μm: +59.17 μm)].

    Because the procedure seemed to stabilize visual acuity, the authors believe this option might be considered in earlier stages of the disease to preserve vision at higher levels. However, it's important to note that the study design did not allow assessment of the efficacy of vitrectomy in diabetic macular edema against the natural course or grid laser coagulation, which is the current gold standard.

    Although they did not observe any visual benefit, there was apparent morphologic benefit with greater reduction in edema in the ILM peeling group.  There are a couple of limitations. This was a small study and it's uncertain whether the results can be generalized to other causes of edema or to cases with evidence of vitreo-macular traction. Nonetheless, the study suggests that ILM peeling does provide an anatomic benefit in these patients.