von Graefe's Cataract Knife Graefe's cataract knife, stainless steel, c 1950s. This small knife was used during a cataract operation to cut into the cornea, the outer transparent part of the eye. The knife was designed by Albrecht von Graefe, a Prussian ophthalmologist during the 1800s and manufactured by John Weiss & Son of London. <a href="https://heritage.rcpsg.ac.uk/items/show/1128">John Weiss &amp; Son, Ltd.; 1787-; Surgical instrument makers</a> c. 1906-1920s 2003/167