REtinal Detachment Outcomes Study (REDOS): study protocol for a factorial, randomized controlled trial.

Background: Few large randomized controlled trials provide strong evidence to guide surgical repair of primary rhegmatogenous retinal detachment (RRD) repair. The purpose of this factorial, single-blind, randomized controlled trial is to analyze and compare the surgical outcomes, functional visual outcomes, complications, and quality of life associated with RRD repair using (A) pars plana vitrectomy only (PPV) or PPV with scleral buckle (PPV-SB) and (B) sulfur hexafluoride gas (SF) or perfluoropropane gas (CF) tamponade.

Methods: Eligible patients with moderately complex RRD will be randomized 1:1 to PPV or PPV-SB and 1:1 to SF or CF gas tamponade. Approximately 560 patients will be recruited to be able to detect a difference of around 10% in SSAS rate between the groups. Patients will be followed using multimodal imaging and quality of life questionnaires after the surgical repair until 1 year postoperative. The primary outcome will be a single-surgery anatomic success (SSAS), defined as the absence of reoperation for recurrent RRD in the operating room. Secondary outcomes will be pinhole visual acuity (PHVA) at 8-10 weeks and 6 months, final best-corrected visual acuity (BCVA), final retina status (i.e., attached or detached), time to onset of RRD recurrence, severity and number of complications, and questionnaire results.

Discussion: This will be the first 2 × 2 factorial RCT examining repair techniques in primary RRD. It will also be the first RCT to compare gas tamponade between the two most common agents. Notably, it will be adequately powered to detect a clinically significant effect size. The use of multimodal imaging will also be a novel aspect of this study, allowing us to compare head-to-head the impact of adding an SB to the retina's recovery after RRD repair and of differing gas tamponades. Until now, the treatment of RRD has been largely guided by pragmatic retrospective cohort studies. There is a lack of strong evidence guiding therapeutic decisions and this trial will address (1) whether supplemental SB is justified and (2) whether longer duration gas tamponade with CF is necessary.

Trial Registration: ClinicalTrials.gov NCT05863312. Registered on 18 May 2023.