Objective To observe the anatomical information and dynamic characteristics of the orbicularis oculi muscle by high-frequency ultrasound,to explor the feasibility of ultrasound evaluation before botulinum toxin injection,and to provide the possibility for personalized and precise treatment to achieve safer and more efficient therapeutic effects.Methods High frequency ultrasound was used to obtain long axis and short axis sectional ultrasound images of 80 bilateral orbicularis oculi muscles from 40 healthy volunteers aged 20-30.The overall morphology and internal echoes were observed,and the distance between the outermost edge of the orbicularis oculi muscle and the outer canthus,the anterior posterior diameter of the thickest part of the orbicularis oculi muscle at the outer canthus level,and the distance between the thickest part of the orbicularis oculi muscle and the epidermis at the outer canthus level were measured.Statistical analysis was performed on the data.Results High frequency ultrasound can clearly display the entire course of the orbicularis oculi muscle and the overall muscle bundle structure.When smiling,the orbicularis oculi muscle on the outer side of the outer canthus can be seen to contract inward and show varying degrees of thickening.The distance between the outermost edge of the orbicularis oculi muscle and the outer canthus of males and females were(27.50±2.58)(25.32±2.17)mm on the left side and(27.35±2.15)(25.11±2.08)mm on the right side,respectively.The anterior posterior diameters of the thickest part of the orbicularis oculi muscle at the level of the outer canthus were left(1.055±0.209)(0.770±0.172)mm and right(1.010±0.171)(0.775±0.162)mm,respectively.The distance between the thickest part of the orbicularis oculi muscle at the level of the outer canthus and the epidermis were(2.450±0.274)(2.860±0.375)mm on the left side and(2.430±0.252)(2.825±0.424)mm on the right side.There was no statistically significant difference in the comparison of the above three indicators on the left and right sides(P>0.05),while there was a statistically significant difference in the mean values of both males and females(P<0.05).Compared with males aged 20-30,females had thicker subcutaneous tissue at the level of the outer canthus and thinner orbicularis oculi muscle,with a shorter distance between the outermost edge and the outer canthus.Conclusions High frequency ultrasound is an effective imaging tool for observing the structure of the orbicularis oculi muscle in young population,and can be used for facial assessment before botulinum toxin injection.