Usually each project is in a different phase. For instance, one project could be almost finished while another project is in the planning stage. I do build lasers specifically for the medical field. But some of the lasers that I do build could possibly have applications in the medical field. Personnally, I think would like have more interaction with the medical profession.
Lasers do make surgery less intrusive.
For instance some lasers are used to elimimate fibriod cysts in women. Before to eliminate fibriods, a women would have to be cut and undergo a long recovery time. No, but I have hopes for my two sons. I suggest that you always stick with what you like. Because in the work environment, you will need that type of motivation.