Prescription Components

We understand that many look at their glasses prescriptions and see only a confusing jumble of numbers, symbols, and abbreviations. The following guide will help you understand this important information.

Here are some examples of how your glasses prescription might look:

Example 1:

SPH CYL AXIS ADD
Right Eye (OD) -3.75 -1.25 178 +2.5
Left Eye (OS) -3.75 -1.50 180 +2.5

Example 2:

    SPH CYL AXIS PRISM
DISTANCE Right Eye (OD) -1.00 -0.25 005  
  Left Eye (OS) -1.75    
NEAR Right Eye (OD) +1.50 -0.25 005  
  Left Eye (OS) +0.75    

Example 3:

R: -3.75 / -1.25 x 178

L: -3.75 / -1.50 x 180

Enter your prescription
  Advised (SPH) Cylinder (CYL) Axis Addition (near) ADD
Right Eye (OD)
  Advised (SPH) Cylinder (CYL) Axis Addition (near) ADD
Left Eye (OS)
Pupillary Distance (PD):  
Prescription Components
Sphere

The “Sph” part of the prescription is the amount of short-sightedness (myopia) or long-sightedness (hypermetropia) present.

The higher the number, the stronger, heavier and thicker the lenses tend to be. You may be advised/recommended high index lenses (thinner and lighter lenses) to make the spectacles more comfortable and lighter to wear and to look more attractive.

Cylinder

The “Cyl” part of the prescription represents the cylindrical power.

This is the amount of astigmatism present.

Axis

This shows the angle at which the cylinder is sitting at.

Prism

This is the correction required to align the eyes so they look straight and work well together.

Prisms bend light to help balance your eye muscles so they work as a pair more comfortably.

Base

This is the direction at which the prism sits – may be UP, DOWN, IN, OUT.

ADD

This is the amount of correction added to your distance prescription to help you focus for reading and close work.

Some other abbreviations you might see:
D.S.
= diopters sphere which indicates that you have only a sphere value and no cylinder value; therefore you need no correction for astigmatism.
D.V.
= distance vision
N.V.
= near vision, sometimes written as N.V.O.
O.U.
= both eyes
X
= axis
P.D.
= pupillary distance