ASHANTI EYEWEAR LIMITED

OPTICAL TERMS

Prism

The correction required to balance the eyes

Base

The orientation of the prism

Sphere (SPH)

Long sighted people will have their prescription proceeded by a +plus sign. Short sighted by a –minus sign. The stronger the prescription the higher the number.

Cylinder (CYL)

Cylinder is only required if you have an astigmatism (visual distortion) caused by an irregular shaped cornea. This condition is fairly common.

A + or – sign indicates the measurement

Axis

Add. This is for the bottom of your bifocals or the amount of extra power that you need to be added for distance This only applies if you have an astigmatism (indicated by the cylinder requirement). The measurement indicates the number of degrees on the axis of the lens that are required.

Plano

This is a lens with no power and is used if you have one perfect eye and one needing correction.