Official Gazette of the United States Patent & Trademark Office Patents 1239(1), Oct 3
2000
A trial lens has a lens surface provided with an index. A stable position of the trial lens on a cornea of a wearer thereof is measured by the use of the index. The position of an optical center of a contact lens to be worn by the wearer can be determined based on the measurement done with the index of the trial lens in order to set the position of the optical center of the contact lens so as to fit contact lenses on individual wearers.