It does not appear that your eyebrows are drooping, as they appear to be in a youthful position. Asymmetry is the norm, and you seem to just have mildly differently placed eyebrows. Botox may help even out the asymmetry.
Is brow asymmetry ptosis?
Brow ptosis, strictly speaking, refers to an abnormally low brow position. It can involve one side (unilateral) or both sides (bilateral). Brow ptosis can result from a variety of causes including congenital, developmental, facial nerve weakness and scarring following surgery or trauma. An abnormally high brow is usually due to distortion or scarring following surgical procedures that involve the forehead. Asymmetric brow position can be due to unilateral brow ptosis or an abnormally elevated brow as discussed above. However, the most common cause of brow asymmetry is due to different anatomical structure between sides which does not fall within the abnormal range but is simply a variant of normal. Side-to-side variation is extremely common and if one looks closely, the majority of individuals will have some degree of difference involving 1 or more parts of the face.
Your photo does not include the whole brow. From what is visible, it appears that medial (inner) 2/3 of the your right brow is lower than the left. A complete evaluation would be required to determine what the underlying cause is using the framework discussed in the previous paragraph. The most likely explanation is anatomical variability and a simple treatment would be selective injections using one of the neuromodulators (Botox, Dysport, Xeomin) to weaken the brow elevators on the left and the brow depressors on the right.
Mario J. Imola, MD, DDS, FRCSC, FACS.