Lens blanks for ophthalmic elements

摘要

A polymeric front optical element blank is provided which may be laminated to a rear optical element blank. The polymeric front blank comprises an optical element having an exterior convex surface and an interior concave surface, with an edge between the exterior convex surface and the interior concave surface. The optical is provided with at least two projections which extend away from and higher than the edge on a side of the optical element having the concave surface. These projections assist in aligning an back optical element during lamination so that the two lenses will not move out of optical registry during lamination, especially where centrifugal forces are used to spread an adhesive between the front and rear lenses. It is preferred that there are at least three projections extending away from and higher than the edge on a side of the optical element having the concave surface.