In most cases, insurance does not cover eyelid surgery. Removal of simple excess skin and fat from the upper and lower eyelids is considered "cosmetic" in most cases, where the goal is primarily improvement of appearance.
In select cases, where the upper eyelid skin hangs so far over the upper eyelid lash margin that this extra "hood" of skin actually blocks the peripheral vision, upper eyelid surgery should be a covered benefit of your insurance plan. In these cases, the upper eyelid surgery is performed for functional improvement, and therefore is "reconstructive" and not cosmetic in nature. It is important that your surgeon properly documents the medical necessity of the planned procedure with your insurance carrier before the procedure is done. Most commonly, this involves sending you to an optometrist or ophthalmologist to have computerized visual field testing, which documents the degree to which your hanging upper eyelids obscure the peripheral vision. The test is then repeated with your excess upper eyelid skin temporarily taped up in a higher (non-obstructing) position to show the improvement of your peripheral vision that should be expected following blepharoplasty for the upper eyelids.
Drooping of the brow and forehead may also contribute to the visual field obstruction, and your plastic surgeon should evaluate whether brow lift (in addition to, or in place of, upper blepharoplasty) is the proper treatment option for you.
Although most insurance carriers will make every effort to deny benefits even for legitimate functional surgery such as this, proper documentation and diagnostic studies will tip the balance in your favor, and your insurance carrier should cover at least a portion of the cost of the operation.