Hello. My 70 year mother has a very large sac under her eye. She has had this sac for years, but it has gotten larger as time went by. It used to get big, and then go down, but for quite a few months, it has stayed this big. There is also a sac under her other eye, but not as big. Sometimes that sac will get smaller, depending on sleeping position. Sometimes the eyelid and the sac are red, sometimes they are not. She has crusting in the morning. No pain. Could you tell me what this could be? Thank you. Jamie