I am sorry to hear about your kitty. I would recommend an examination by his vet when their office reopens. If your kitty is lethargic, not eating, painful, or has a fever (rectal temperature above 102.5) then a visit to the emergency vet would be recommended. With swelling like this we would worry about residual infection, reaction to suture material, foreign body in the eye, seroma or hematoma in the socket, tumor presence in the eye. In the meantime you can try applying a cool compress/ice pack (wrapped in a thin cloth) over the area if it seems uncomfortable for 10 minutes every few hours.