To guarantee maximum wearing comfort, an exact fitting procedure must be followed for each type of lens. The following recommendations for centering ZEISS lenses take into account the respective centration requirements as well as the requirements for the center of rotation and field of view.
The measured value is the dioptric power in the major reference point of a lens and is measured in the focimeter using a defined measuring technique.
The prescribed or wearing power is the dioptric power experienced by the user in the major reference point in a defined wearing situation.
Sometimes specially produced lenses are required outside the standard range.
This may be advisable if the wearing comfort of the lenses can be improved,
e. g. with specially computed, thinner lenses produced using the OPTIMA technique.
Various groups of people, including employees working for public authorities, in the business sector, in industry and in science and research as well as the general public comply with the standards issued by the DIN German Institute for Standardization.The DIN authorities play a major role in the compilation and publication of standards within CEN and ISO.