US PATENT SUBCLASS 351 / 168
.~.~ Multifocal

Current as of: June, 1999
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351 /   HD   OPTICS: EYE EXAMINING, VISION TESTING AND CORRECTING

41  DF  SPECTACLES AND EYEGLASSES {29}
159  DF  .~ Ophtahalmic lenses or blanks {10}
168.~.~ Multifocal {4}
169  DF  .~.~.~> Gradually varying focal power
170  DF  .~.~.~> With prismatic segment
171  DF  .~.~.~> Three or more foci
172  DF  .~.~.~> Multiple elements

DEFINITION

Classification: 351/168

(under subclass 159) Subject matter wherein the ophthalmic lens has at least two vision fields of different focal strength.

(1) Note. The different focal strength may be produced by using material of different refractive indices or different curvatures.

SEE OR SEARCH THIS CLASS, SUBCLASS:

161, for multifocal eye contact-type lenses.

164, for multifocal lenses with light filtering.