Unilateral Double Eyelid Formation after Botulinum Toxin A Injection: A Case Report.

Botulinum toxin injection has been widely used for facial rejuvenation, with high rates of efficacy and patient satisfaction. In this article, we describe a reproducible phenomenon of unilateral double eyelid formation with the treatment of upper facial rhytides using botulinum toxin. A 38-year-old man was given onabotulinum toxin A injections in the frontal stria and glabellar lines. The procedure was repeated after 6 months. Unilateral double eyelids were noted twice on the right side about 7 days after each injection. The maintenance time for each procedure was about 1 month. The rhytides improved about 3 days after each injection and were maintained for about 4 months. No adverse effects were observed. This rare phenomenon could be due to the compensatory increased strength of the levator palpebrae superioris muscle and the anatomical structure of the patient's right eyelid.