Three-dimensional imaging of the inner limiting membrane folding on the vitreomacular interface in diabetic macular edema

To report the findings of fine folds on the retina obtained by spectral-domain optical coherence tomography (OCT). A retrospective non-comparative case series; 26 eyes of diabetic macular edema (DME) patients who underwent vitrectomy were observed using three-dimensional (3D) images of OCT preoperatively and postoperatively. The specimens were investigated immunohistochemically. Using only tomography, non-tractional vitreoretinal interfaces were observed in 15 eyes and tractional vitreoretinal interfaces in the other 11 eyes. Using 3D imaging, we observed fine folds in 11 eyes among 15 cases showing non-tractional interfaces. Based on these findings, the state of the vitreoretinal interface was classified into 3 patterns. Group 1, both tomography and 3D imaging showed smooth retinal surfaces. Group 2, tomography showed a smooth retinal surface, but 3D imaging showed fine folds on the retina. Group 3, both tomography and 3D imaging showed a tractional vitreoretinal interface with an obvious epiretinal membrane and/or taut posterior vitreous cortex. The fine folds in group 2 disappeared and macular edema improved after inner limiting membrane (ILM) peeling, and the CRT of groups 2 and 3 reduced significantly. The fine folds were confirmed to involve the ILM because type IV collagen expression was detected in the surgically obtained specimens. We observed tangential fine folds of the ILM. These were detected by using only 3D imaging, and might be useful for investigating the optimal indication of vitrectomy for DME.