a pre - formed intrastromal corneal insert for use in treating keratoconus and similar dystrophies and methods of using the same . an intrastromal insert of the present invention comprises a biocompatible polymer and may be used to adjust corneal curvature , thereby correcting vision abnormalities caused by disease or other surgical procedures . the insert may be comprised of a circular or semi - circular ring shape or a portion of a ring , or “ arc ”, encircling the anterior cornea within the frontal circumference of the cornea . the insert may be used in multiples to form complete arcs or to form constructs of varying thicknesses . the insert of the present invention possesses a cross section that results in a low scattering level of light .