Contact lens for correction of astigmatism
CA 2035102 C · Owner: Schering Corporation · Inventors: Townsley, Malcolm
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A contact lens for correcting astigmatism. The front surface has a central optical zone and an outer carrier having two points of maximum thickness located at an oblique angle of about 110° to 130° as measured from the vertical axis of the lens. The anterior surface of the lens is symmetrical about its vertical axis. The carrier tapers from the points of maximum thickness to thin portions at the top and bottom of the lens. The rear surface of the lens has an outer spherical base curve zone, an inner toric zone, and an intermediate transition zone having thickness that gradually increase from the base curve zone to the toric zone. By making the radius of the base curve zone substantially …
Read the whole patent
Listed from its CIPO record in Patent Yard's archive of Canadian patents past their term. Its claims, description and drawings are in the CIPO record and on Google Patents, and the Claude kit works from them.
Why it's free to use
- Filed January 28, 1991 and granted June 3, 1997. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended January 28, 2011.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by January 28, 2013.
- We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
Timeline
Timeline From CIPO dates
Sources & verification
Official CIPO records
Everything on this page comes from the CIPO record linked above. Contains information licensed under the Open Government Licence – Canada.