Nipple has open wound after breast reduction. Should I be worried? (photos)

I am sorry to hear about the complication you have experienced.  Treatment regimens will vary from one practice to another;  ultimately, your plastic surgeon will be your best resource when it comes to accurate assessment and advice. Having said that, based on the appearance of the wound, I would likely recommend that you continue with current treatment including sterile dressing changes.   Sometimes, removal of any unhealthy tissue and/or expose features will help expedite the healing process. A focus on good nutrition and  avoidance of any type of nicotine product is also important. Closure of these  types of wounds are usually not necessary and may expose you to potential problems with infection. You will likely find that the wound will close over the course of the next several weeks.  It is often surprising how well the body "remodels"; you may be pleasantly surprised when it comes to the final appearance of the area. It is possible, depending on the final appearance of the scar and shape of the areola long term, that revisionary breast surgery will be helpful. Best wishes.