Aims To investigate characteristics of intraoperative iatrogenic retinal breaks in 23-gauge vitrectomy for idiopathic macular hole and classify the breaks based on their causes to analyse the risk factors.

Methods This retrospective study enrolled patients with stage 3 or 4 idiopathic macular hole who underwent 23-gauge vitrectomy in Beijing Tongren Hospital from July 2015 to August 2018. The intraoperative iatrogenic retinal breaks were classified into three types: by induction of posterior vitreous detachment (type 1), by peripheral vitreous cutting (type 2) and by others (type 3). The types, incidence and distribution of the breaks were analysed, and all clinical features were compared between eyes with and without the breaks.

Results A total of 364 eyes from 341 patients were recruited. Twenty-five breaks from 24 eyes (6.6%) were encountered, 52% (13/25) of which distributed in the superior region. Type 1 and type 2 breaks contributed 52% (13/25) and 44% (11/25) to all, respectively. Eyes with stage 3 and stage 4 holes showed no significant differences in incidence or distribution in type 2 breaks. No breaks occurred on the surface of lattice degenerations. All clinical features showed no significant differences between eyes with and without the breaks.

Conclusion Distribution of intraoperative iatrogenic retinal breaks shows no preference for the superior or inferior region. Induction of posterior vitreous detachment and traction from peripheral vitreous cutting are major causes of the breaks, which classify them into two main types. The presence of lattice may not be one of the risk factors if treated properly.