TITLE: RCT of air tamponade versus fluorinated gas tamponade for rhegmatogenous retinal detachment DESIGN: Non-inferiority RCT of 150 patients from 10 UK centres AIMS: To assess whether air tamponade is non inferior to gas tamponade for the repair of RRD treated with vitrectomy.

PRIMARY OUTCOME MEASURE: Primary anatomical success with single operation at 24 weeks.

STUDY OBJECTIVES To assess whether air tamponade is non inferior to gas tamponade for the repair of RRD with superior breaks treated with vitrectomy and to assess how cost-effective air tamponade is compared to gas tamponade BACKGROUND Rhegmatogenous retinal detachment (RRD) is the most common form of RD developing when there is a retinal 'break' that allows the ingress of fluid from the vitreous cavity into the subretinal space. There are three main current options for the management of RRD, namely pneumoretinopexy, scleral buckling and vitrectomy (PPV). Vitrectomy is currently performed for the majority of RRDs in the UK. Tamponade in PPV is usually performed by complete filling of the vitreous cavity with fluorinated gases diluted in air at iso-volumetric concentrations which do not expand (e.g., 20% SF6 or 14% C3F8).

RATIONALE FOR CURRENT STUDY The use of air instead of fluorinated gases in primary RRD treated with vitrectomy has been the subject of much debate recently. Air being non expansile and short lived it offers the prospect of quicker rehabilitation and less risk and avoids the use of environmentally damaging fluorinated gases. The question of whether air offers equivalence to gas for uncomplicated RRD with mainly superior breaks has not been adequately answered, as reviewed in a recent systematic review and meta-analysis where the certainty of evidence was judged very low. This type of detachment is the commonest at approximately 60% of the cases in the BEAVRS database and representing approximately 4,800 RRD in the UK per annum. There has been significant interest in air recently with the announcement of the European chemical agencies proposed ban on fluorinated gases.

There are several potential benefits of using air over gas to repair detached retinas.

1. Speedier visual recovery, which may mean earlier return to work or normal activities.
2. Avoiding expansile fluorinated gas-related complications such as raised eye pressure, reducing the number of post-operative visits and medications needed after surgery.
3. Fewer restrictions after surgery (able to fly and drive sooner and shorter restrictions on anaesthetic agents)
4. Decreased environmental impact by reducing greenhouse gas use. If air was proven to be non-inferior to gas, then patients with RRD treated by vitrectomy would likely prefer it STUDY DESIGN RCT of people presenting with uncomplicated RRD treated with vitrectomy comparing air to gas tamponade.

Participants will be randomised 1:1 between air tamponade and gas tamponade. Randomisation will be performed using a secure web-based randomisation system at the time of surgery.

Inclusion Criteria:

• Primary uncomplicated RRD undergoing vitrectomy.
• Phakic and pseudophakic eyes
• Retinal breaks superiorly between 3 and 9 o'clock, and that are separated by less than 4 clock hours.

Exclusion Criteria:

• Absence of PVD
• Age 40 years or younger
• PVR grade C or above
• Aphakia or anterior chamber lens
• Retinal breaks greater than 1 clock hour in size
• Retinal breaks that exist below 3 and 9 o'clock on both the nasal and temporal sides.
• Retinal breaks at or posterior to the vessel arcades
• Current or previous -6D myopia or greater (or axial length >26millimetres (mm))
• Chronic RRD judged by the presence of subretinal bands and other signs of -chronicity or by history of visual loss for >28 days.
• Significant inflammation, choroidal detachments, hypotony (<6 millimetres of mercury (mmHg) preop)
• Previous open-globe injury, or endophthalmitis
• Current or previous posterior uveitis or choroiditis
• Any intraocular surgical procedure within 4 weeks other than laser/cryotherapy
• Any other condition that, in the opinion of the investigator, would prevent the participant from granting informed consent or complying with the protocol.