Three-Dimensional Analysis of Peeled Internal Limiting Membrane Using Focused Ion Beam/Scanning Electron Microscopy

Purpose To reevaluate the effect of internal limiting membrane peeling during vitrectomy on the Müller cell damage, we examined the ultrastructure of the internal limiting membrane by using focused ion beam/scanning electron microscopy (FIB/SEM). Methods A total of 12 internal limiting membranes obtained during surgery in both the macular hole and the idiopathic epiretinal membrane groups were processed for observation by FIB/SEM. Three-dimensional structures of the internal limiting membrane were analyzed. Results The number of cell fragments in the macular hole group was 5.07 ± 1.03 per unit area of internal limiting membrane (100 μm2). The total volume of cell fragments was 3.54 ± 1.24 μm3/100 μm2. In contrast, the number of cell fragments in the epiretinal membrane group was 12.85 ± 3.45/100 μm2, and the total volume of cell fragments was 10.45 ± 2.77 μm3/100 μm2. Data for both values were significantly higher than those observed in the macular hole group (P = 0.0024 and P = 0.0022, respectively, Mann-Whitney U test). No statistical difference was found for the mean volume of the cell fragment between the two groups. Conclusions All of the internal limiting membrane examined in this study showed cell fragments on the retinal surface of the internal limiting membrane. As compared with macular hole, epiretinal membrane exhibited a higher number and total volume of cell fragments, indicating that internal limiting membrane peeling for epiretinal membrane might have a higher risk of causing inner retinal damage. Translational Relevance FIB/SEM was a useful tool for three-dimensional quantitative analysis of the internal limiting membrane.