Masashi Sakamoto, Izumi Yoshida, Ryuya Hashimoto, Hidetaka Masahara, Takatoshi Maeno Department of Ophthalmology, Toho University Sakura Medical Center, Sakura, Japan Purpose: To identify risk factors for retinal breaks during macular hole (MH) surgery.Patients and methods: This retrospective, observational, comparative study included the medical records of 364 consecutive patients (382 eyes) who underwent vitrectomy for MH at Toho University Sakura Medical Center between January 2012 and May 2017. The patients comprised 135 men and 229 women with mean age 67.6±8.0 years. Six eyes with a pre-existing retinal tear treated by laser photocoagulation before MH surgery were excluded. Data on sex, age, presence or absence of lattice degeneration, axial length (measured using an IOL Master®), preoperative refraction, whether or not combined lens extraction/vitrectomy had been performed, whether or not the lens was pseudophakic before vitrectomy, and whether or not a posterior vitreous detachment had been created intraoperatively were collected. The lattice degeneration status was classified as none (0), treated using laser photocoagulation (1), or untreated (2).Results: The only item identified in logistic regression analysis with the backward elimination method to be a significant risk factor for retinal breaks during MH surgery was the presence of lattice degeneration (P<0.001).Conclusion: Ophthalmologists should be aware of the increased risk of retinal breaks during MH surgery in eyes with lattice degeneration. Intraoperative retinal breaks may be less likely to occur in eyes with lattice degeneration treated by photocoagulation preoperatively. Keywords: macular hole, iatrogenic retinal breaks, vitrectomy, lattice degeneratio