Hoya Array identifier question

[ak47]

Have a new patient that appears to be wearing a Hoya Array lens and is very happy with it. Nasal markings are "Y75." The 5 indicates 1.67, can anyone explain what the 7 means?

[bretk0923]

Corridor length, if I'm not mistaken. If the extra number is present, it means that it is a fixed corridor length, and the number corresponds to the ones digit of corridor length. In your case, the "7" would correspond to 17mm fixed corridor length