Design of needles used in ophthalmic microsurgery

ABSTRACT

A range of microneedles has been specifically developed to meet the demanding requirements of todays microsurgery. Surgical needles are usually hand-made from high quality stainless steel and are manufactured in a wide spectrum of types, shapes, and lengths. Choice of needle design and geometry is dictated by many factors, among them the location, accessibility, and nature of the tissue to be sutured. Because corneoscleral tissue is tough, dense, compact and resistant, the best needle design for cataract microsurgery comprises a combination of a triangular cutting profile at the tip, with transition to a spatula-like cutting profile in the body. A length of 5 to 6 mm, a diameter of 150 to 300 micro, and a radius of curvature of 2.00 to 2.75 mm have been found most convenient, with a half-or a 3/8-circle [135°], or a bicurve shape. Needles of 5/8-circle [225°] are unsuitable for cataract microsurgery. Flat [ski] needles and half-curved needles are used for passing suture material, especially fascia lata and steel wire, for long distances, Quarter-circle [90°] spatulated needles are ideal for strabismus surgery