Certified Surgical Technologist (CST) Practice Exam

The trephine is the instrument specifically designed for performing keratoplasty, particularly for removing the cornea. This specialized surgical tool has a circular blade that allows for precise and controlled excision of the corneal tissue. During keratoplasty, whether it's a full thickness or partial thickness procedure, the trephine creates a uniform, circular cut, facilitating the removal of the cornea in a manner that preserves the surrounding structures and prepares the site for transplantation or other corrective measures.

The other instruments mentioned do serve important roles in various ophthalmic surgeries but are not suited for the removal of the cornea in keratoplasty. The Westcott scissors are generally used for cutting delicate tissue but lack the specific design to excise a corneal button. The oculotome is useful for making precise incisions or cuts in the ocular tissues but does not serve the same purpose as the trephine for corneal excision. The phacoemulsifier is primarily used in cataract surgery to break up and remove the lens of the eye, not the cornea. Thus, the trephine is the clear choice for corneal removal during keratoplasty.