What could be causing my eyelids to itch then swell for a year after eyelid surgery? I did not have eye allergies prior (Photo)

the first step would be to see your surgeon. it looks like you had surgery on your levator muscle? you may be 'allergic' to the deep sutures placed during surgery? i have definitely seen that as second opinions and have gone back to remove reactive sutures and place non reactive ones. when there is no swelling are there palpable 'bumps' on your lids? 
from a healing point of view you should be finished and this seems unusual. a second opinion may help, although your first step i think is with you primary surgeon. good luck!