Is it OK to use hydrogen peroxide on a rhinoplasty scar?

Some PS recommend that you use peroxide; others do not. Best to ask the PS who performed your rhinoplasty what his/her postoperative protocols recommend. At a concentration of 3 - 5 %, hydrogen peroxide is mildly irritating to the skin and mucous membranes so the postoperative guidelines will provide directions for diluting it.

Ultrasonic Rhinoplasty device Piezo®:

In traditional Rhinoplasty, surgical instruments known as rasps and osteotomies (hammer and chisel) are used to reshape the nasal bones by removing the hump and/or narrowing the nasal bone width. These tools are relatively imprecise and their use can lead to contour irregularities, etc. if not used in the proper manner. Recently, a technology that uses sound waves has been developed to contour nasal bones in a precise and far less traumatic way when compared to traditional techniques. Ultrasonic, or Piezo, Rhinoplasty is now the most advanced technology available for minimally traumatic nasal bone reshaping and hump removal during Rhinoplasty. There will be hardly any bruising and swelling which will make the recovery period a lot easier for the patient.

It is always in patient's best interest to follow instructions of the surgeon, in particular when dealing with fresh scar/incision. good luck.