Abstract: A method of fitting rigid gas permeable contact lenses comprising the steps of:providing a set of lenses of differing BCOR values, but the same optical corrective power;fitting a patient with a lens to determine an acceptable BCOR value for the patient;determining the corrective prescription for that patient; andsupplying the patient with a lens having an acceptable BCOR value and the correct prescription.The lens supplied is manufactured in the same geometry and fitting characteristics as the lens from the set used in fitting and adjusted to the correct prescription power from the fixed power by diffractive means.

Abstract: A consumable laser mask for forming a visual lens, especially a contact lens, in which at least a portion of the light passing through the lens is focussed by diffractive means. The laser mask is shaped to provide the diffractive means in the finished lens, and is made from a polymeric material with a thickness such that no residue is left at the completion of the laser ablation process. The invention also includes a method of manufacturing a lens using a consumable laser mask in accordance with the present invention.

Abstract: A method of correcting or alleviating presbyopia in humans comprising (a) fitting a first contact lens to a first eye, and (b) fitting a second contact lens to the other eye. Each of the lenses has a first power provided by the shape, curvature and material of the lens to provide a refractive corrected image and a second power provided by diffractive means to provide a second corrected image, the second power being additive to (or subtracted from) the first power. The lenses are fitted so that one has a refractive near image optical power and the other has a refractive distance image optical power, and the diffractive means of the lenses are arranged so that the amount of the light directed into the near image by one lens is substantially greater than that directed into the far image by that lens, and the amount of light directed into the far image by the other lens is substantially greater than that directed into the near image by that other lens.

Abstract: A consumable laser mask for forming a visual lens, especially a contact lens, in which at least a portion of the light passing through the lens is focussed by diffractive means. The laser mask is shaped to provide the diffractive means in the finished lens, and is made from a polymeric material with a thickness such that no residue is left at the completion of the laser ablation process. The invention also includes a method of manufacturing a lens using a consumable laser mask in accordance with the present invention.