Should a doctor know where the arteries in the face are to avoid causing blindness or skin necrosis from filler?

There is no way to know 100% where the arteries, veins and nerves are exactly on every patient, because there are many variations in the anatomy, so they can be a little higher, lower, deeper, in a different direction, etc. But what a physician who does inject fillers on the face should know is general guidelines, where those structures (arteries, veins, nerves, muscles) are deep, where they are closer to the skin, if there is a particular area that involves more risk, if there is a particular mark in the bone that can tell the injector where is variation. Knowing all these, helps the injector, if a cannula or needle is safer, if it has to be injected deep or superficially, if it has to be injected with a bolus technique, or fanning technique, if it needs to injected with mini deposits, also if aspiration on the syringe is needed, etc. Finally it is also important to know how to detect an intravascular injection and the treatment.

Hello, while it may not be possible to know exactly where the vessels are during facial injections, it is safe technique to withdraw before injecting to know whether the needle is within a vessel or not. Additionally, there are some instruments to help visualize the vessels prior to injection that some injectors use. Always make sure to visit an experienced injector who is familiar with their facial anatomy. 

Yes, but keep in mind, this side effect is extremely rare. I recommend injections with cannulas to limit complications. Best, Dr. Emer