Terminology
Article Index
Start | minus/plus | spherical | cylinder
myopia | hyperopia | presbyopia
look-under | look-over | plano
Prescriptions

 

Look-under

When correction is needed for distance viewing but none for near by a look-under lens can be the answer. There is a cut out on the bottom of the corrective lens so one can look underneath the lens. Usually only an option for people with minus powers equalling a reading addition, e.g.  Sperical -2.00  Add +2.00.

 

Look-over (reading glasses)

When correction is needed for reading but none for far distance viewing look-over lenses (correction under, plano above) or glasses (half height frame) can be used.

Also corrective lenses with a cut out in the top part can be useful for people who need correction for far sightedness but none for reading and have to read instruments above their heads.

 

Plano lenses

Plano lenses have no corrective powers and are used as protection or as filter lenses e.g. sunfilter, eye protectors, snow goggles etc.