<prompt> In retinal sealingretinopexy, what is used?Sulphur hexafluorideCarbon monooxideNitrous oxideS02  <response>: The gases commonly employed for tamponading the retina are sulphur hexafluoride SF6 or perfluoropropane C3F8. These are injected after sealing the breaks with cryopaxy. The gas bubble remains in contact with the tear for 5-7 days and are absorbed later. Ref: Parsons 22 nd edition page no. 335 