A myringoplasty knife with blades set at 90° and 115° is a specialized surgical instrument used in ear surgeries, specifically for procedures like myringoplasty, which involves repairing the tympanic membrane (eardrum). The knife features blades with angles of 90° and 115° to facilitate precise dissection and incision in the delicate ear structures. These angles allow for optimal access and control during surgery, enabling the surgeon to effectively remove damaged tissue or graft for eardrum repair.