Multifocal contact lens with a difference power on the back surface
CA 2107828 A1 · Owner: Roffman, Jeffrey H. · Inventors: Crowe, Carl G.; Guillon, Michel; Poling, Timothy R.
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
Disclosed is a multifocal contact lens having a first optical power on a portion of the optical region of the back surface of the lens, a second optical power on another portion of the optical region of the back surface portion of the lens, and a third optical power over the entire optical region of the front surface of the lens. The first optical power in combination with the third, optical power produces a basic distance corrective, optical power while the second optical power more, positive than the first, produces in combination with the third optical power a difference corrective power to provide the appropriate near focal length for an individual requiring bifocals. This type of …
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 October 6, 1993. No grant is recorded for it in Canada; had it been granted, its 20-year term would have ended October 6, 2013.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by October 6, 2015.
- 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.