The First Corrective Glasses with Glued Titanium Frames.
No Need to Drill
Plastic lenses in current conventional frames are either press fitted or attached with screws or rivets in drilled holes. All of these means of attachment apply stress to the lenses that can lead to them breaking or in some circumstances negatively affecting the vision of sensitive patients (Kunststoffe international 6/2012, p. 12). In order to address these difficulties Lensbond Research & Development GmbH, Salzburg, Austria, launched a new type of rimless glasses in 2011 where the bridge and temple arms were not drilled and screwed to the lenses, but glued instead. The company has now extended its range of designs adding a titanium frame to the existing portfolio of variously colored polyamide frame components.
These titanium parts that are only 0.8 mm thick are however not bonded directly to the lenses. The metal is formed into a shape similar to the eye of a needle and then pressed onto an injection molded plastic shoe. This is then glued to the lens in exactly the same way as all other Lensbond glasses. To do this the optician uses a patented device to remove a layer just a few microns thick from the lens under a stream of cleaned air at the point to be glued. After that the adhesive is applied to the components which are held in a jig and capillary action then distributes this evenly throughout the gaps between them. 24 hours later the system reaches its ultimate strength.
Lensbond tested an alternative method on the first generation prototypes four years ago. This involved overmolding the titanium hinge with polyamide and then bonding this to the lens. According to the company founder Wilhelm Anger these glasses have been in use since 2009 without any problems.
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