Silicone oil is used for recurrent retinal detachments or complicated retinal detachments including PVR (proliferative vitreoretinopathy). It can be a valuable tool to prevent blindness.
Most retinal detachments are caused by a retinal tear, or hole, in the retina. In either case, this allows for communication between the vitreous cavity and the potential space underneath the retina. Fluid may leave the vitreous and accumulate underneath the retina, causing a rhegmatogenous retinal detachment (rhegma = with a hole).
A vitrectomy with gas with or without a scleral buckle are common ways to surgically repair retinal detachments.
Occasionally, a retina can redetach and usually shortly after the first surgery. Common reasons include an additional retinal tear, or, it is conceivable that an extra tear(s) was overlooked and not treated.
Options include repeating the vitrectomy with gas and possibly adding a scleral buckle if one is not present. This usually does the trick.
Repeated retinal detachments due to additional tears usually persuades me to consider using silicone oil to fix the detachment. In addition, a condition called proliferative vitreoretinopathy (PVR) often requires using silicone oil.
PVR can cause retinal detachments as membranes (scar tissue) form on the surface of the retina and start to pull. This pulling can cause multiple retinal tears.
Intraocular gas works by “plugging” the retinal tears or retinal holes. The gas bubble, when properly positioned against the tear/hole, prevents fluid from getting underneath the retina causing a recurrent detachment. As the gas is absorbed, the bubble will become so small that any untreated or new hole will be uncovered. Thus, the retina can detach again.
Think of silicone oil as a non-absorbable gas bubble. Since the silicone oil is not absorbed, it stays large enough to always cover the holes. This makes it highly unlikely that a redetachment can occur.
Normally, intraocular gas is preferred as it eventually absorbs after reattaching the retina. A separate procedure is not required to remove the gas.
Silicone oil does require removal and the vision is usually poor with the oil in the eye, however, when warranted, the oil is likely to prevent re-detachment.
Silicone oil is a great tool to repair retinal detachments. Repeated operations can be mentally straining and can be a hardship on the patient and family. Also, with each new detachment, the likelihood of permanent vision loss increases, thus, the fewer detachments the better.
Too many retinal physicians, using silicone oil is a last resort to keeping the retina attached. Often doctors wait until the retina has detached 3-4 times before considering oil (in fairness, I used to be one of them).
My belief is that oil should be used earlier to stop the vicious cycle of re-detachment and re-operation. By preventing recurrent detachments, the vision can be better preserved in these complicated cases.