Silicone oil has a variety of indications for use in vitreoretinal surgery. It provides long-term or permanent support and tamponade to the retina in complicated retinal detachments such as are seen in proliferative vitreoretinopathy, giant retinal tears, retinal detachments secondary to proliferative diabetic retinopathy, and failed primary retinal detachment surgery. Silicone oil is most useful in eyes that require superior support. Although it is most often used after primary or secondary surgery, primary usage can be considered in patients in whom gas tamponade might be ill-advised, children who are unlikely to comply with positioning, or patients who must fly urgently. Primary silicone oil usage has also been suggested for the management of necrotizing retinitis, such as cytomegalovirus retinitis or acute retinal necrosis. Silicone oil is clear and allows easy visualization of the retina postoperatively. See Chapter 20 for a detailed discussion of the indications and surgical usage of silicone oil.