Immediate subretinal fluid displacement from the buoyant force of a small gas bubble in pneumatic retinopexy: Insights into the potential mechanism of retinal displacement following retinal detachment repair.

PURPOSE To demonstrate how a small gas bubble injected into the vitreous cavity in pneumatic retinopexy (PnR) for rhegmatogenous retinal detachment (RRD) causes immediate displacement of subretinal fluid and to gain insights into the potential mechanism of retinal displacement.Methods: Three patients with RRD who underwent PnR were enrolled and prospectively followed. All patients underwent ultra-widefield fundus photography at baseline and at 1-2 minutes after intravitreal gas injection. RESULTS In all cases, the ultra-widefield fundus photograph demonstrated immediate displacement of subretinal fluid, suggesting that the buoyant force applied to the retina by the bubble was responsible for the displacement of subretinal fluid. The results were extrapolated to determine the buoyant force applied by a small and large gas bubble as in PnR and pars plana vitrectomy (PPV). We determined that the buoyant force applied with a larger bubble in PPV was substantially greater and this may lead to retinal displacement. CONCLUSIONS Intravitreal gas applies significant buoyant force to the detached retina and subretinal fluid which leads to substantial and rapid displacement of subretinal fluid. Understanding the impact of the buoyant force of the gas bubble on the detached retina can provide insight into possible mechanisms of retinal displacement.