In vitrectomy for epiretinal membrane is there usually a gas bubble put in.

Yes for ....: 4 different gases used in vitreoretinal surgery: air, sulfur hexafluoride (SF6),perfluoroethane (C2F6) and perfluoropropane (C3F8). In the vitreous cavity, these gases are colorless, odorless , inert, when injected into the vitreous cavity, air does not expand, whereas pure SF6, C2F6 and C3F8 gases do. High surface tension between gas and fluid allows effectivesealing of a retinal opening.