Which type of suture instrument is designed for tying sutures?

The correct answer is needle holders, which are specifically designed to securely grasp and manipulate needles during suturing. This instrument has a locking mechanism that allows the surgeon to hold the needle firmly while it is passed through the tissue. The design of needle holders enables precise control during the suturing process, making them essential for quickly and accurately tying knots.

In contrast, scissors are used for cutting tissue and sutures, not for tying sutures. Portex refers to a brand of medical devices, often related to anesthesia, and does not pertain to suturing instruments. An Algerbrush is an instrument used for scraping or removing tissue, which is unrelated to the process of tying sutures. Understanding the specific functions and purposes of surgical instruments is crucial for any surgical assistant, particularly in ophthalmic procedures.