Move the lens slowly until the micro-engravings are:
• Symmetrical in relation to the graduations
• Aligned on the line corresponding to the PRP (Prism Reference Point) of the lens
The PRP value of Essilor progressive lenses is 4mm. This may vary depending on the manufacturer
of the lenses.
The lens is centered and ready to be blocked.
To block the lens, refer to the section Centering a lens > Blocking a lens (F p.62).
b. Centering a lens using manufacturer markings
Prerequisite:
• The markings must be clear
• The lens must at least have the following markings:
1. Far vision mark
2. Centering marks