It varies depending on a number of factors and if any other type of surgery is being done at the same time. So you need to ask your surgeon for specifics.
JCH MD
If you're going in for just silicone oil removal and there are no complications during surgery, it should be a really quick procedure (a few minutes). However, it can NOT be done in office, instead it requires a trip to the OR (so count on the total time spent to be a few hours: pre-op waiting+op+post-op waiting).