Purpose:To assess the relationship between day 1 postoperative intraocular pressure (IOP) and patient demographic information, indication for vitrectomy, lens status, tamponade medium (air, perfluoroethane, sulfur hexafluoride), and laser treatment.Methods:A prospective observational study of all patients undergoing pars plana vitrectomy (PPV) by a single surgeon within 1 case study. All patients had IOP recorded 1 day after surgery. None of the patients had postoperative antiglaucoma medications. All patients undergoing PPV were previously pseudophakic or underwent combined surgery.Results:Of a final cohort of 161 patients, 6% had raised IOP (defined as >30 mm Hg). A parsimonious regression model showed no strong correlation between raised IOP and type of gas tamponade (P = .028 for C2F6, P = .067 for SF6, air was the reference category) and a moderate association with the number of laser burns (P = .067).Conclusion:The use of gas tamponade, in particular C2F6, does not constitute justification for pre/postoperative antiglaucoma prophylactic treatment. In addition, we postulate that careful consideration should be given to the frequency of laser burns during PPV.