Use of 25% sulfur hexafluoride gas mixture may minimize short-term postoperative hypotony in sutureless 25-gauge pars plana vitrectomy surgery

Background: The purpose of this study was to compare postoperative intraocular pressures and percentage of vitreous cavity gas fill one day following 25-gauge pars plana vitrectomy with 20% versus 25% sulfur hexafluoride (SF₆) gas fill. Methods: This was a retrospective review of 187 consecutive cases of 25-gauge pars plana vitrectomy with complete fluid/gas exchange. The main outcome measures included percentage of gas fill of the vitreous cavity and intraocular pressure on postoperative day one. Results: Fifty eyes underwent 25-gauge pars plana vitrectomy with 20% SF₆ tamponade and 137 with 25% SF₆ tamponade. On postoperative day one in the 20% SF₆ group, there were five (10%) patients with hypotony (intraocular pressure ≤ 5 mmHg) and none in the 25% SF₆ group. Mean intraocular pressure was 9 ± 2.5 mmHg and 16.8 ± 2.4 mmHg for the 20% SF₆ and 25% SF₆ groups, respectively (P < 0.01). None of the patients had postoperative intraocular pressure > 23 mmHg. Mean vitreous cavity gas fill on postoperative day one was 70.7% ± 10% in the 20% SF₆ group and 89.5% ± 2.2% in the 25% SF₆ group (P < 0.01). There was no difference in the number of phakic patients needing cataract surgery between the groups. Conclusion: A slightly expansile concentration of 25% SF₆ gas can be safely and beneficially used in 25-gauge vitrectomy surgery to increase the amount of gas fill in the vitreous cavity and prevent postoperative hypotony.