To guarantee maximum wearing comfort, an exact fitting procedure must be followed for each type of lens. The following recommendations for centring ZEISS lenses take into account the respective centration requirements the centre of rotation requirement and the field of view requirement.
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.
The standards issued by the DIN authorities are complied with the participations of various groups of people from public authorities, the business sector, industry, science and the general public. The DIN authorities play a major role in the compilation and publication of standards within CEN and ISO.