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.