Progressive power lenses - part 8

Patents have been taken out in recent years by several major lens manufacturers disclosing progressive designs of unusual configuration. Some simply embody improvements in the design and manufacture of the lenses. For example, US Patent 8550622:2013¹ assigned to Hoya Lens Manufacturing in the Philippines, which allows for input of the intermediate centration distance (CD) for a given working distance, obtained either by means of optometric instrumentation such as the Nidek Accommodator AA-2000, or the Grand Seiko Autorefractor GR-2100/GR-3100K. In the absence of such instrumentation it is suggested that the intermediate CD be calculated from a knowledge of the distance CD and the intermediate working distance.