Fig. 9. Silicone oil sealing a retinal break due to its surface tension. Inset. A silicone bubble prolapses through the retinal hole into the subretinal space. Curves: Normal pressure, p, of the subretinal oil bubble drives it back into the vitreous cavity, as a function of the prolapsed volume V(p). Continuous curve indicates circular retinal hole. Dotted curve indicates linear break. Po is maximum of p reached when the prolapse is most steeply curved (situation 2). (From Petersen J: The physical and surgical aspects of silicone oil in the vitreous cavity. Graefes Arch Clin Exp Ophthalmol 225:452, 1987.)