Lens testing throughout the production process

To offer effective progressive lenses, Essilor puts the wearer at the heart of a five-step process, called the Dioptric Loop. Optical testing is part of every step of the loop.

1. Collection of physiological data: the visual functioning of each test-wearer is studied to draft specifications that are compliant with the nature of his/her vision.

2. Optical design: the physiological data is converted digitally using an optical computation program with successive optimizations.

3. Prototype manufacturing: test lenses are custom-cut through several sophisticated technical steps.

4. Measurement check: advanced checking instruments enable reliable and precise lens testing. The optical properties and parameters are checked in the lab.

5. Optical testing: the test-wearers try out the lenses adjusted for them. To ensure their full satisfaction, the tests are conducted using the double-blind technique and the testers are asked precise questions, to analyze both their objective and subjective impressions.

There are two possibilities at the end of this loop:

- the lens test is not conclusive: the researchers restart their work from the beginning.

- the test-lens is satisfactory: it is released for sale