Lateral Eyebrow Lifting and Eye-Opening Point Injection With Botulinum Neurotoxin: Anatomical Perspective

BACKGROUND: The orbicularis oculi muscle plays a critical role in eye-opening and closure. Identifying precise injection sites for botulinum neurotoxin can improve both functional and esthetic outcomes, particularly for conditions like blepharospasm or ptosis. MATERIALS AND METHODS: Three fresh cadavers were dissected, separating soft tissues from bones to observe the muscle layers. A 29-year-old Korean female was administered a botulinum neurotoxin injection. Before the injection, ultrasound was used to identify the lateral superior part of the orbicularis oculi muscle. The injection point, at the edge of the superolateral orbital rim, received a 1-unit intradermal injection of letibotulinum neurotoxin. Changes in eye-opening were observed 4 weeks postinjection. RESULTS: Dissection revealed intermingling of the frontalis and orbicularis oculi muscles, with the orbicularis oculi muscle exclusively present at the edge of the superolateral orbital rim. This point was targeted for the injection, resulting in improved eye-opening and eyebrow elevation. The patient reported a GAIS score of 2, indicating noticeable improvement. DISCUSSION: Targeting the edge of the superolateral orbital rim for botulinum neurotoxin injections effectively reduces involuntary muscle contractions, facilitating easier eye-opening and eyebrow lifting. The anatomic specificity of this site minimizes risks to surrounding muscles. These findings suggest potential clinical applications for enhancing eyelid function and esthetic outcomes. Further research with larger samples and long-term studies is recommended to validate these results and explore additional benefits.