An eyelid without double eyelid may appear smaller because of the overhanging eyelid. (see why double eyelid makes the eye bigger?) If one eye has double eyelid and the other absent double eyelid, the later may be mistaken for droopy eyelid. I have come across a few patients who were referred to me for droopy eyelid when in fact the problem is absent of double eyelid in the smaller eye and the treatment of choice is to create a double eyelid. There are several ways of doing these either with non-surgical method (glue or tape) or surgery (both suture technique or incision technique).
Right eye appears to have droopy eyelid due to poorly
formed double eyelid. Creation of double eyelid balances
Right eye appears droopy due to absent double eyelid.
When the double eyelid is created with tape the two
eyes appear the same size.
Below is the article which I recently published in Malaysian Journal of Medicine highlighting this condition: