Development of secondary epiretinal membrane after vitrectomy with inverted ILM flap technique to treat a macular hole.

Purpose: To report a rare case of secondary epiretinal membrane (ERM) formation that appeared to be associated with the temporal hemi-inverted internal limiting membrane (ILM) flap, and to discuss its possible pathogenic mechanism. Observations: A 74-year-old woman visited our hospital because she was aware that the central vision of her left eye was not normal. Her decimal best-corrected visual acuity (BCVA) in the left eye was 1.0. She was diagnosed with stage 3 MH with a diameter of 162 μm, and she underwent phacovitrectomy using the temporal hemi-inverted ILM flap technique. The MH was closed, and the decimal BCVA was still 1.0 one week post-surgery. However, at 13 months after the surgery, metamorphopsia developed with an M-chart score of 0.5°, and the decimal BCVA was reduced to 0.8. Optical coherence tomography revealed a secondary ERM with strong traction on the papillomacular bundle (PMB) of the retina. Several days later as the traction increased, the BCVA decreased to 0.6, and a second vitrectomy was performed. At one month after the reoperation, the BCVA had improved to 0.9, and at six months post-surgery, the M-chart score improved from 0.6° to 0°. Conclusions and importance: The temporal hemi-inverted technique is beneficial in improving the closure of MHs, and it reduces the risk of iatrogenic damage of the PMB. It also preserves macular sensitivity. However, for small MHs, the relatively high rate of spontaneous closure combined with the potential risk of postoperative ERM formation in the long term, suggests that the temporal hemi-inverted ILM flap technique should not be used in such cases. Conventional ILM peeling may be more appropriate as a primary treatment for small MHs.