Alcon, Inc.

Michael Ruland

Justyna Justynska-Reimann

Markus Grebe

André Wicklein

The present invention relates to a method and an apparatus () for determining a coefficient of friction at a test site () on a surface () of a contact lens (). The apparatus comprises: a lens holder () arranged at least partially in a receptacle (); a slide () comprising a counter surface () made of lapped aluminum for contacting the test site (); a load generator () configured to apply a predetermined normal load (Fn) between the counter surface () and the test site; a drive () configured to generate a sliding movement between the counter surface () and the contact lens in direction located in a plane perpendicular to the normal load (Fn); and a force sensor () configured to measure a tangential frictional force (Ft) between the test site and the counter surface () along the direction of the sliding movement.

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Dossenheim, Germany

Michael Ruland