Is lower eyelid surgery dangerous if I still have filler in tear troughs?

Thank you for your question. In my experience it is best to remove all filler from the lower lid with an injection of Vitrase before any surgery. Lower eyelid filler can still be present after 3.5 years. So I would have the filler removed and then re-evaluate the surgical approach.

Without seeing photos, it is difficult to give you specific recommendations.  However, in general, prior filler treatment does not complicate or increase the risks associated with lower lid blepharoplasty.  You are correct in that we sometimes recommend fully dissolving the filler prior to surgery.  Hyaluronic acid fillers are hydrophilic and can create long-standing edema.  Restylane usually dissolves around 1 year but can last longer in the tear trough region.  I recommend that you see a facial plastic surgeon with extensive experience in eyelid surgery.
Best of luck.

Hyaluronic acid fillers placed under your eyes can cause swelling which may be delayed a number of months. Based on your history it sounds like at least part, if not all of your problem is the swelling from the filler. I would strongly suggest you find a physician who will use hyaluronidase to dissolve the filler in the areas that are excessively swollen. Until this problem is treated properly and resolved you will not be able to determine whether eyelid surgery is even needed much less what should be done. Get a second opinion from a physician experienced with under eye fillers ad the use of hyaluronidase.

It is highly doubtful that you still have filler in your tear trough area 3.5 years ago.  Filler is temporary. Most likely, you are seeing fat pockets that come with aging.  See a highly experienced board certified plastic surgeon for an in person evaluation.