Sulfur Hexafluoride 20% Versus Air 100% for Anterior Chamber Tamponade in DMEK: A Meta-Analysis

PURPOSE:To compare intracameral 20% sulfur hexafluoride (SF6) versus 100% air as tamponade for graft attachment in Descemet membrane endothelial keratoplasty (DMEK). METHODS:Using an electronic database search on MEDLINE and CENTRAL from inception to December 2017, we performed a literature review and meta-analysis including all comparative studies of SF6 at a 20% concentration (20% SF6) versus pure air (100% air) for anterior chamber tamponade in DMEK. The primary outcome was the rebubbling rate at the final observation. The secondary outcomes were 1) the graft detachment rate, 2) mean difference (MD) in best-corrected visual acuity (BCVA), 3) manifest refraction spherical equivalent, 4) central corneal thickness (CCT), 5) percentage of endothelial cell loss (ECL), and 6) rate of pupillary block by the final observation. Statistical analysis was performed using RevMan5.3 software. RESULTS:Five retrospective studies were included, assessing 1195 eyes (SF6 277; air 918). The main indication for surgery was Fuchs endothelial dystrophy (SF6 85.2%; air 86.2%) and bullous keratopathy (SF6 10.8%; air 10.0%). Overall, studies were of moderate to good methodological quality. Patients in the SF6 group required 58% less rebubbling procedures (risk ratio 0.42, 95% confidence interval (CI), 0.31–0.56, P < 0.0001). No differences were found regarding BCVA improvement (MD 0.03, 95% CI, −0.05 to 0.11, P = 0.49). SF6 was associated with a minor hyperopic shift (MD 0.37 D, 95% CI, −0.95 to −0.21, P = 0.21). No differences were found regarding CCT, ECL, and rate of pupillary block (P > 0.05). CONCLUSIONS:In DMEK, 20% SF6 tamponade and longer postoperative time supine were associated with 58% fewer rebubbling procedures, and an ECL not statistically different from using 100% air.