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BACKGROUND The purpose of this study was to investigate and identify predictors for idiopathic macular hole persistence after pars plana vitrectomy with dye-assisted internal limiting membrane peeling. METHODS In a retrospective case series, 160 eyes underwent identical vitreoretinal procedures performed by the same surgeon. Baseline characteristics and preoperative optical coherence tomography were evaluated regarding the postoperative anatomical outcome. RESULTS n overall closure rate of 86.3% (138/160) was achieved. According to the Gass classification system, the closure rates were 100.0% (11/11) in Stage 2, 95.0% (57/60) in Stage 3, and 78.7% (70/89) in Stage 4. Thereby, a significant influence of preoperative best-corrected visual acuity and basal hole diameter was observed. Especially, idiopathic macular hole with a basal hole diameter of ≥800 μm and a best-corrected visual acuity of ≤20/100 had a 4 and 6 times higher risk to persist, respectively. On the other hand, age, gender, bilateral occurrence, symptom duration, and lens status did not have an effect on the surgical outcome. Furthermore, perifoveal pseudocysts were associated with a higher closure rate in Stage 4 idiopathic macular hole. CONCLUSION Simple clinical parameters such as best-corrected visual acuity, basal diameter, and perifoveal pseudocysts are efficient predictors and might be used to expand the validity of the Gass classification.

The purpose of this study was to investigate the ultrastructure of the membrana limitans interna (internal limiting membrane, ILM) and to evaluate alterations to the retinal cell layers after membrane peeling with vital dyes. Twenty-five patients (25 eyes) who underwent macular hole surgery were included, whereby 12 indocyanine green (ICG)- and 13 brilliant blue G (BBG)-stained ILM were analyzed using light, transmission electron and scanning electron microscopy. Retinal cell fragments on the ILM were identified in both groups using immunohistochemistry. Comparing ICG- and BBG-stained membranes, larger cellular fragments were observed at a higher frequency in the BBG group. Thereby, the findings indicate that ICG permits an enhanced separation of the ILM from the underlying retina with less mechanical destruction. A possible explanation might be seen in the known photosensitivity of ICG, which induces a stiffening and shrinkage of the ILM but also generates retinal toxic metabolites.