The corneal allogenic intrastromal ring segment (CAIRS) is a novel surgical modality for treating corneal ectasia. In the original technique, semicircular pieces of donor cornea are produced manually with a specially designed, double-bladed circular trephine (Jacob CAIRS trephine, Madhu Instruments), with an inner blade (outer diameter of 6.7 mm), an outer blade (inner diameter of 7.5 mm) and a groove width of 0.40 mm. Then, the 360-degree arch segment is bisected with a surgical knife. The SK Intacs (Addition Technology, Inc.; Sunnyvale, CA) is used as a guidewire to implant the CAIRS. Although this facilitates the insertion, including the SK Intacs increases surgical costs. Further, in this technique, the segment's thickness can be unpredictable because the donor corneal tissue's thickness is variable. It also may limit the visual outcome because it treats different keratoconus with a uniform nomogram. In this video, we describe a novel femtosecond laser-assisted technique for producing personalized CAIRS with variable thickness, length, and width. We also describe an insertion technique that does not require SK Intacs.