My infant ears are different in sizes. Is there any solution to treat this without surgery involved? (photos)

You pose some good questions, Mom.  Facial asymmetry (as well as asymmetry throughout the body) is common--the two sides of the face and body are like sisters, and not twins.  Without examining your child, I would propose that 4mm is not a significant difference between ear sizes, and likely not noticeable by the average observer.  For example, 2-3mm difference between ear projection from the head is considered acceptable in ear-pinning surgery.Newborn ears have soft cartilage due to high level of circulating maternal estrogen; thus, a variety of cartilage issues (prominent ear, Stahl's deformity, helical rim problems, etc) may be addressed with ear splinting in the newborn period.  This being said, your child appears to have a more prominent earlobe of the ear shown in the 1st and 3rd photos, and because the earlobe is fleshy and without cartilage, I don't think an ear splinting device such as Earwell would help with this.  On rare occasions, I've seen the very bottom of the helical rim cartilage (the cartilage accounting for the outer rim of the ear) account for a prominent ear lobe; this is potentially splintable, even at an older age of 8 weeks.Made of cartilage, connective tissue, and skin, ears reach adult size at approximately age 5-6+ years.  Furthermore, your child will develop the mastoid prominence (a bump of bone found on most adults immediately behind the ear lobe) at ~age 2 years, which may change the appearance of the earlobe.  An overly prominent earlobe may be treated surgically with an incision behind the ear and conservative tissue removal or sutures.  The name of this is otoplasty (a general term for ear-shaping surgery), or lobule-plasty.My recommendation would be to find a plastic surgeon who is experienced in ear deformities and ear surgery for an evaluation.  An in-person exam with such a provider would hopefully give you more information and some more definitive answers.  Good luck!