Abstract: The surgical correction is carried out with the aid of thermocoagulation of the cornea along the lines appropriately oriented with respect to the minimum refractive power meridian and to the distal points of the eyeball central optic zone. Two of such lines are essentially circular arcs, while two other lines are the sides of two angles the bisector of which is the minimum refractive power meridian. Provision is also made for a device for preliminary marking out of the eyeball, aimed at carrying out thermocoagulation along said lines. The device is in fact a cylinder-shaped housing which accommodates special elements adapted to be brought in contact with the corneal surface upon placing the housing on said surface in order to obtain the impressions of the lines along which thermocoagulation is then carried out.