Keraring AS is the first and only intrastromal ring segment with progressive thickness. It allows for even greater treatment customization options when planning to achieve optimal visual and refractive outcomes for each individual case. It is available in 150o, 160o, 180o, and 330o arc length, 5mm diameter and the following progressive thicknesses (clockwise and counter-clockwise): 250μm to 350μm, 200μm to 300μm and 150μm to 250μm. The indications for using the Keraring AS are keratoconus, ectasia after LASIK, and irregular astigmatism after transplantation with asymmetric topographical features.