Ritchie

Sphere (SPH) - the amount of lens power

Examples:

Cylinder (CYL) - This indicates the amount of astigmatism.
If nothing appears in this column or if it is DS, means you have no astigmatism

Examples:

AXIS - If an eyeglass prescription includes cylinder power,
it also must include an axis value, which follows the CYL power and is preceded by an 'x'.

Examples:

Addition
(ADD)

ADD - magnifying power applied to the bottom part of multifocal lenses, s always a + power.

Examples:

Pupillary Distance (PD)

The distance between the centre of one pupil
to the centre of the other pupil is the PD.
Prescription glasses are made so that the distance
between the optical centres of the glasses' lenses,
is the same as your PD.

Prism UP/Down, In/Out:

Most Prescription Don't Have this/

Your prism helps your eyes to work together more comfortably by correcting their muscle balance.

Note:

If you have a prism correction, you will also have a base direction that will state one of the following - Up, Down, In or Out.
Down might be indicated by ‘DN’
You might have more than one Prism value per eye.
You will have a Base direction for each Prism correction.
The example below shows the prism required for distance.
You will use the H-Near and V-Near prism for reading as this might be different from your distance prism.