Why does one eyelid look larger than the other? (Photo)

You have congenital ptosis of the left upper eyelid caused by a lack of insertion of a structure called the levator. It can be repaired in the office under local anesthesia. 

Thank you for asking. This appears to be an eyelid ptosis (drooping) which could be caused by a variety of issues including muscle overstretching. The picture does not show the eyebrows and forehead fully which is necessary to properly make a diagnosis. This may be a correctable surgical issue- see a board certified surgeon who can perform PTOSIS repair (not just a blepharoplasty which is largely a skin issue). Best wishes!

It appears you have left upper eyelid ptosis (droopy upper eyelid). See an oculoplastic specialist for evaluation and possible eyelid ptosis surgery.

While some asymmetry of the face and eyes is normal if you have ptosis of one eyelid surgery can be effective in improving this. Ptosis repair involves tightening of the levator muscle to eliminate eyelid drooping. If excess upper eyelid skin is hooding the eye and needs to be eliminated, an incision is made in the crease at the top of the lid and excess fat and skin are removed. The incisions are closed and sutured on the underside of the skin. I suggest making an appointment with a board certified plastic surgeon who is experienced in ptosis repair.

You have a droopy left upper eyelid (i.e. ptosis), causing the eye to look smaller.  This can be corrected by raising the eyelid (i.e. ptosis repair), and under local anesthesia.  See a specialit to learn more and best wishes.  

You need to get checked out by an oculoplastic surgeon or neuro-ophthalmologist so they can determine what is wrong with your eye. It can reflect a larger issue with the brain.