There are many reasons for a drooping upper lid to begin with. In adults, however, commonest among them are rigid contact lens use for prolonged periods, neurological following 3rd nerve palsy, the nerve that supplies that muscle, diabetes related, trauma, following cataract surgery. If the cause is neurological, all you have to do is wait if the MRI and blood workup is fine ( as is the case with you) and treatment with a course of vitamin B complex. I assume, since you were operated upon, the cause following examination in your case was believed to be muscle realted or more appropriately aponeurotic which is the case with contact lens induced ptosis. Following surgery immediately, there may be some residual ptosis which can be due to slight weakness of the muscle as a result of handling during surgery or even lid oedema that appears to be drooping but goes away after a while. It can also be actual undercorrection where there has been less shortening of muscle than needed but you have to wait a few months and then maybe a revision surgery would be needed. This is not as uncommon as you would think. As far as the double vision goes, one cause is trauma to the superior rectus or superior oblique muscles during surgery. There has been time evolved following surgery so it would be a good idea to have the doulbe vision evaluated so the paretic muscles are determined and the exact cause identified.