Female 41 Caucasian
It is difficult to tell from the picture if this is actually a bulging muscle or a vessel. If it is, a muscle, treating the area with Botox would relax the corrugator muscle. Relaxing this muscle would make the bulge much less noticeable.
Generally the bulge between the brows relates to overuse & hypertrophy of the procerus muscle and also the corrigator supercili. In most cases, a botulinum toxin like Botox or Dysport works great to weaken & atrophy this muscle so that it is less bulging, and continues to get better & better over time as there is weakening & thinning out of the muscle from prolonged disuse. Your dermatologist can fix this nicely & safely for you.