BS EN ISO 8624:2020

What is ISO 8624 about?  

ISO 8624 discusses spectacle frames for ophthalmic optics. ISO 8624 outlines a measuring system for spectacle frames and related vocabulary. It is applicable to spectacle frames with fronts that are intended to be symmetrical. 

The boxed lens system of measurement and definitions of spectacle frames are based on rectangular boxes that circumscribe the lens shapes. 

Who is ISO 8624 for? 

ISO 8624 on spectacle frames for Ophthalmic optics is useful for: 

• Manufacturers of spectacle frames for Ophthalmic optics 
• Test centers for Ophthalmic optics 
• Regulatory authorities 

Why should you use ISO 8624? 

Spectacle frames are based on rectangular boxes that circumscribe the lens shapes and are used for the determination of the dimensions of the spectacle front, where the upper tangent is both common to the right and left lens shapes and regarded as being horizontal. 

ISO 8624 guideline provides principal terms of the boxed lens system, complimentary terms of the boxed lens system, and measuring system for spectacle frames for ophthalmic optics. This helps improve the designs and symmetry which give comfort to the wearer. 

What’s changed since the last update? 

BS EN ISO 8624:2020 supersedes ISO 8624:2011, which has been withdrawn. BS EN ISO 8624:2020 has some technical changes with respect to ISO 8624:2011. These include: 

• The informative annex with its complementary definitions has been transferred to 3.2 
• Minor asymmetry of only the nasal bearing surfaces has been included in this edition. Since such asymmetry does not affect the lens shapes, only the definition of bridge height is affected. See the explanation in 3.2.6, note 2 to entry 
• The plane of the lens shape has been redefined and now relates to the orientation and position of the vertical centre line, in turn, based on the apex of the groove in the frame and not a dummy lens 
• The definition of the overall length of the side for those without joints has been amended slightly, while the figures now take account of the 3-dimensional nature of spectacle fronts where there is a significant face form angle 
• An informative annex (annex a) has been added to discuss the measurement of 3-dimensional spectacle frames