GLASSES PRESCRIPTION

UNDERSTANDING YOUR GLASSES PRESCRIPTION

After every sight test your optometrist will present you with a copy of your optical prescription. This indicates the power your glasses will be made up to. It is a legal requirement that you are given a copy of your prescription at the end of the sight test.
Your prescription will be made up of a number of numerical figures which can look unusual and confusing. Below is an example of what your optical prescription may look like. We at FLY like it keep things simple, so we have designed this page to help our customers understand their prescription better.

  Sphere Cylinder Axis Add H Prism V Prism VA
R +0.50 -0.75 95 +2.00 1.00 BASE IN 0.00 6/6
L +2.00 -1.25 110 +2.00 0.00 1.00 BASE UP 6/6
Right
Sphere
+0.50
Cylinder
-0.75
Axis
95
Add
+2.00
H Prism
1.00 BASE IN
V Prism
0.00
VA
6/6
Left
Sphere
+2.00
Cylinder
-1.25
Axis
110
Add
+2.00
H Prism
0.00
V Prism
1.00 BASE UP
VA
6/6

SPHERE
The lens power needed to correct short or long-sightedness. Its an equal power over the whole lens. Usually if the sign is (+) then you are long-sighted and if the sign is (-) you are short-sighted. The word plano (pl) or a (∞) symbol indicates no power is needed. The sphere, cylinder and add all increase in 0.25 increments.

CYLINDER
The lens power to correct astigmatism. Astigmatism is where the eye needs corrective power in one angle/meridian only. Not everyone needs astigmatism corrected. Sometimes you might see ‘DS’ in the CYL column, this simply means there is no astigmatism. 

AXIS
The direction of the cylinder. Between 0-180 degrees. 

ADD
The extra power of magnification required to help us see for near vision such as  reading (near add), or for intermediate vision such as computer work (Inter add). Usually given to patients over the age of 40. 

BVD
Back vertex distance is the distance between your eyes to where the glasses sit on your nose. It is not always stated and normal only given to high prescriptions. 

PRISM
Lens power needed to correct muscle imbalances in the eye. Most people will not need this. 

BASE 
This will always come after the power given for a prism. It indicates which direction the prism in your lens needs to be. 

VA
Stands for visual acuity. The numerical figure of the clarity of your vision from a specific distance. 20/20 vision is the US equivalent to our 6/6. 

PUPILLARY DISTANCE PD
Your pupillary distance is the distance between your eyes. It is usually measured between the centres of both pupils. This can normally be difficult to take as it can be tricky to find the exact centre of the pupils. However there are a number of ways this measurement can be taken. You can ask your optometrist for your PD as they do not normally state this on your prescription.
If you don’t have your PD, we may be able to make your glasses up using the average PD measurement. If for any reason we require a more accurate measurement our optometrist will email you and instruct accordingly once you place your order. Alternatively, you can send your current glasses to us, and we can take the measurements from there.