M
- Magnification
- Magnification of photography
- magnifier
- main beam
- main lens
- major portion
- major reference point
- Manufacturer
- margin
- matching lens
- mean reflectance
- mean transmittance in the ultraviolet A spectrum TUVA
- measured IOP
- measured power
- meniscus lens
- meridian of a lens
- meridian of a surface
- meridional power
- metal frame
- mineral glass
- minus-power lens
- monocular aid
- monocular field
- Monocular indirect ophthalmoscope
- monocular pupillary distance
- multifocal lens
- multifocal semifinished lens blank
measured power
Dioptric power at a specified point on a spectacle lens by measurement using a given method. The dioptric power in the design reference point of a lens, measured in the focimeter. In Carl Zeiss multifocal lenses, the measured power differs from the as-worn power for two reasons:
- firstly, because of the different geometry of the trial lens used in refraction and the spectacle lens
- secondly, due to different ray paths during measurement in the focimeter and during actual use of the lens in front of the eyes. See As-worn power.