Ronald Rabbetts explains some recent changes to the British Standards relevant to all who are involved in verification
The revised standard also includes the 'as-worn' pantoscopic angle, being the angle in the vertical plane between the visual axis when the eyes are in the primary position and the normal to the demonstration lens in the frame at its boxed centre.
This angle should not be confused with the angle of side, which confusingly is known in the US as the pantoscopic angle - it is hoped that the US will rename this as the 'frame pantoscopic angle' to differentiate it from the lens angle.
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