A Real-World Comparison Of Sf6, C3f8, And Air For Anterior Chamber Tamponade In Endothelial Keratoplasty.

The use of fluorinated gases in corneal transplantation has significant environmental implications. SF6 has one of the highest global warming potentials (GWP) of any known substance, whereas C3F8, though also a greenhouse gas, has a considerably lower GWP, making it a relatively less harmful alternative for intraocular procedures. This study compares rebubbling rates in patients undergoing Descemet's Membrane Endothelial Keratoplasty (DMEK) or Descemet Stripping Automated Endothelial Keratoplasty (DSAEK) with anterior chamber (AC) graft tamponade using 100% air, perfluoropropane (C3F8), or sulfur hexafluoride (SF6) at varying concentrations. 

A single-center retrospective analysis was conducted at Frimley Park Hospital, United Kingdom, including all patients who underwent Endothelial Keratoplasty (EK) between January and December 2024. 

A total of 56 patients underwent EK, of which the records of 49 eyes undergoing DMEK and 7 undergoing DSAEK were reviewed. Among the DMEK group, 32 patients underwent DMEK alone, while 17 had a combined procedure with cataract extraction and intraocular lens implantation. The most common indications were Fuchs' dystrophy (38 cases), pseudophakic bullous keratopathy (7 cases), and re-do DMEK following graft rejection (4 cases). 

Among the analyzed cases, in the DMEK group, 21 eyes received C3F8 at varying concentrations (1%, 2%, 3%, 5%, 7%, 10%), 25 eyes received SF6 (15%), and 3 eyes had an air fill. The overall rebubbling rate was 10.2% (5 eyes): no eyes in the C3F8 group, 3 eyes (12%) in the SF6 group and 2 eyes (66.6%) in the air group. One case of pupil block with C3F8 2% (4.7%) led to graft failure, requiring a re-do DMEK with SF6 after three months. One case of high intraocular pressure (IOP) in the C3F8 group required additional glaucoma eye drops. Three cases in the SF6 group required rebubbling within two weeks. All cases in the air group required rebubbling within one week. In the DSAEK group, air was used exclusively, and no cases required rebubbling. 

These findings suggest that C3F8 may be a preferable alternative to 20% SF6 following DMEK, as it is associated with lower rates of graft detachment and rebubbling while maintaining an acceptable safety profile. Longer tamponade duration of C3F8 (average anterior chamber bubble persistence at postoperative week 1: 58% [C3F8] vs. 10% [SF6]) may contribute to its efficacy. Due to C3F8's longer tamponade with visual axis sometimes affected, SF6 provides better one-week visual outcomes, though one-month results are similar in both groups. Gas selection did not appear to influence outcomes in DSAEK. Future studies are warranted to assess long-term endothelial health, graft survival, and the environmental impact of gas choice.