The Jacob CAIRS Trephine is a double blade trephine used to create allogenic donor tissue ring of desired thickness for making the Corneal Allogenic Intrastromal Ring Segments (CAIRS). These segments are used in the CAIRS procedure. CAIRS has been successfully used in patients with keratoconus globally. This surgical approach is aimed primarily at flattening the cone (ectatic cornea) and regularizing the topography thereby improving vision. In the CAIRS procedure, instead of using plastic ring segments, donor corneal tissue strips are inserted intrastromally into the mid-peripheral recipient cornea making the procedure safer than synthetic segments while also allowing it to be performed in a much wider spectrum of patients ranging from mild to very steep and very thin corneas where synthetic segments are not possible.