Will Lower Blepharoplasty Make Edema Under Eyes Worse?

If you are having a blepharoplasty done, it would be best if a transconjunctival approach is used.

Making a skin incision approach will possibly damage the lymphatic drainage channels as well as adversely affect the eyelid muscle. This might lead to worsening "festoons".

The blepharoplasty will not likely change the swelling aspect of your eyelid problem. If you have thin, crepey, redundant skin, I would recommend an Erbium laser skin resurfacing approach to tightening the skin, without actual skin excision.

Posting a photo really would be ideal to get a better recommendation.

With blepharoplasty, fat is removed and sometimes fluid can become worse. Unless fat really needs to be removed, filler under the eyes can be a better option than surgery. You should really consult with a surgeon who specializes in eyelid surgery (like an oculoplastic surgeon) to see if there is swelling and if surgery is necessary. The technique for removing the fat bags can make a difference, whether through the conjunctiva or through the skin.  It is a possibility that the swelling may get worse.