A
- Abbe
- Abbe number
- absorptance
- absorptive lens
- Active ophthalmic instrument
- addition power
- additive power trial case lens set
- Adjusting rail
- afocal lens
- aid microscope
- aid telescope
- alignment reference marking
- angular magnification
- antireflection coating
- apex
- apical angle
- arm
- as-worn power
- aspheric lens
- aspherical surface
- astigmatic difference
- astigmatic effect
- astigmatic lens power
- astigmatic power lens
- astronomical telescope
- atoric lens
- atoroidal surface
- auxiliary beam
- auxiliary lenses
additive power trial case lens set
Train of spherical, cylindrical or spherocylindrical combination of trail case lenses, in which the measured back-vertex power at the last surface equals the meridional sum of the labelled values of the train lenses when each element is placed in its specified frame cell (see ISO 12857).