Ridge under eye after Restylane in tear troughs. Is this normal? Is it due to the technique? (Photo)

Injecting in the tear trough area with ANY product is difficult and
requires much skill. Most of what you are experiencing is swelling from
the procedure itself; however, it does appear that the Restylane may have been placed too superficially.  It's always best to evaluate the results of
fillers in the tear trough about 3-4 weeks after the treatment.  If, at that time, you still have the "ridges", you can
ask your doctor to dissolve the Restylane with hyaluronidase, which will
start working within hours.  After the product is dissolved, I would wait another 3-4 weeks prior to seeking additional injections.  I feel only "core" injectors should perform cosmetic injectables (facial
plastic surgeons, plastic surgeons, dermatologists, or occuloplastic
surgeons). This is because we all have a keen understanding of facial
anatomy and the effects of injecting fillers in different
regions of the face.  Be sure you see an experienced "core" injector before getting more filler in the future.  Patience is difficult when your face is
involved, but give it another couple weeks.  I wish you well!

That appears to be superficial product, which has to do with technique and product placement. I would wait a full 2 weeks for all the swelling to settle, and then assess. If it is superficial product it can be removed with hyaluronidase. "This answer has been solicited without seeing this patient and
cannot be held as true medical advice, but only opinion. Seek in-person
treatment with a trained medical professional for appropriate care."