Gas versus GaslEss surgery for full thickness Macular hole (GEM): study protocol for a randomised, assessor-masked, surgical feasibility study.

introductionPars plana vitrectomy with intravitreal gas tamponade has been the standard treatment for full-thickness macular holes (FTMHs) for the last 30 years. Gas tamponade has multiple drawbacks: it results in very poor vision for several weeks, limiting patients' ability to drive and work; many undertake intensive face-down posturing for about a week after surgery, to float the gas bubble onto the macula; gas is cataractogenic and prevents adequate fundus examination; it can elevate intraocular pressure, mandating regular hospital review; patients cannot fly and the fluorocarbon tamponades are extremely potent and long-lived greenhouse gases.Six uncontrolled retrospective case series have reported promising results utilising novel FTMH surgery without gas tamponade.The study aims to establish if it is feasible to recruit, retain and evaluate patients with FTMHs into a pivotal randomised control trial of vitrectomy without gas tamponade. The main clinical aim is to collect preliminary safety and efficacy data, comparing gasless with standard vitrectomy. METHODS AND ANALYSIS: This randomised, assessor-masked, surgical, feasibility study aims to recruit 60 participants with FTMH from six English National Health Service sites. Participants will be randomised 1:1 to either standard vitrectomy, gas tamponade and postoperative posturing, or to gasless vitrectomy without posturing. Gasless surgery involves folding a hinged flap of internal limiting membrane over the hole, secured by gravity and a viscoelastic gel. Participants attend postoperatively for examination and imaging. The main feasibility outcomes are recruitment and retention rates, cross-over and participant treatment acceptability. The main clinical outcomes are primary FTMH closure (3 months), best-corrected visual acuity (6 months) and adverse events. ETHICS AND DISSEMINATION: South Central-Hampshire A research ethics committee gave a favourable opinion of the study (Reference: 24/SC/0019, 16 February 2024). The study results will be published in a peer-reviewed journal. TRIAL REGISTRATION NUMBER: NCT06079593 .