CSN EN ISO 13666 This document defines terms relating to ophthalmic optics, specifically to blanks, finished spectacle lenses and fitting purposes. Terms relating to processes and material for fabrication and surface treatment (other than some specific terms relating to coatings), and terms relating to defects in materials and after optical processing are given in ISO 9802. Original English text of CSN EN Standard. The price of the Standard included all amendments and correcturs.